SAFFORD MAR 9, 1997 COTTON PLANTING DATE ADVISORY +-------------------------------------------------------------------------+ | | | v | ********* | ** 175 ** | ********* | | ^ normal | | | +---------+---------+---------+---------+---------+---------+---------+---+ 0 200 400 600 800 1000 1200 1400 HEAT UNITS (HU) ACCUMULATED FROM JAN 1 - MAR 8 v = Heat Units accumulated from JAN 1 - MAR 1 PLANTING INFORMATION -------------------------------- Soil temperatures at planting depth are closely linked to air temperatures. Air temperature forecasts can therefore provide help in determining when soils will be sufficiently warm for germination. Air and soil temperature data from AZMET show soil temperatures reach acceptable levels (for germination) when high temperatures reach the low 80s and low temperatures remain in the upper 40s. WEATHER UPDATE -------------------------------- MAR 9 - MAR 15 WEATHER: WEEKLY HIGH LOW HEAT UNITS 30 yr Norm.: 72 37 41 Last Year : 73 41 45 HUs are running about 9 days behind normal. HUs last week = 38. FORECAST: Mostly sunny, warm and dry this week. Very warm temperatures are expected in all production areas early in the week. A slight cooling trend is expected by Friday. Expect both day and night temperatures to run 5-7 F above normal for the week. Little chance for rain in central and western Arizona; slight chance for light showers in southeast on Monday and Tuesday. This week's temperature forecast should generate acceptable soil temperatures for germination in central and western production areas. Growers planning to plant this week are encouraged to closely monitor 5-day forecasts as conditions can (and usually do) change rapidly at this time of year. Last Week's 8am Soil Temp: Max = 49.5 MAR 8 ; Min = 41 MAR 2 AGRONOMY UPDATE -------------------------------- At the beginning of the 1997 Arizona cotton season, many of our strategies are oriented toward an early, optimum date of planting in an effort to get our fields and plants off to an early start. Recent research and experiences in Arizona cotton production systems have shown us the value of realizing an early crop, that is moving through and completing the primary fruiting cycle in a complete (high fruit retention level), fast, and efficient fashion. In realizing maximum yield potential, planting date is indeed very important. An early, optimum date of planting should take into account soil temperature con- ditions, the 5 day forecast, and the variety type. Optimum soil temperatures for planting are 65 F at 8 A.M., with absolute minumums of 55 F. (JCS 3/8/97) SAFFORD MAR 16, 1997 COTTON PLANTING DATE ADVISORY +-------------------------------------------------------------------------+ | | | v | ************ | **** 247 *** | ************ | | ^ normal | | | +---------+---------+---------+---------+---------+---------+---------+---+ 0 200 400 600 800 1000 1200 1400 HEAT UNITS (HU) ACCUMULATED FROM JAN 1 - MAR 15 v = Heat Units accumulated from JAN 1 - MAR 8 PLANTING INFORMATION -------------------------------- Air and surface (planting depth) soil temperatures are closely linked during the planting season. Forecasted air temperatures can therefore provide guidance as to when soils will be sufficiently warm for good germination. Air and soil temperature data collected by AZMET show soil temperatures reach acceptable levels (for good germination) when high temperatures reach the low 80s and low temperatures remain in the upper 40s. WEATHER UPDATE -------------------------------- MAR 16 - MAR 22 WEATHER: WEEKLY HIGH LOW HEAT UNITS 30 yr Norm.: 74 37 46 Last Year : 81 41 68 HUs are running about 2 days behind normal. HUs last week = 73. FORECAST: A weak storm system will pass through Arizona Monday producing partly cloudy skies, a chance for showers and slightly cooler temperatures. A rapid return to warm, dry weather is expected following the passage of the storm. Tempera- tures are forecast to run 10 degrees above normal Wednesday through Friday. Present long range forecasts indicate another storm system will approach the Pacific coast on Thursday; growers planting late in the week are encouraged to monitor the development of this system. Last Week's 8am Soil Temp: Max = 53.7 MAR 15 ; Min = 47.1 MAR 9 AGRONOMY UPDATE -------------------------------- Planter calibration can be an important step in getting a desirable stand pop- ulation. Planting rates based upon the number of lbs. of seed planted per acre can vary a lot due to wide variations in seed size and the number of seeds per lb. for different varieties. Generally acceptable plant populations range from 20,000 to 70,000 plants per acre (ppa). Optimal populations range from 25,000 to 50,000 ppa. For example, if a variety with 5,000 seeds per lb. was planted at a rate of 14 lbs. per acre, a total of 70,000 seeds per acre would be planted. If 50% of the planted seed emerged, then a stand of 35,000 ppa (70,000 X 0.50 = 35,000) could be realized. (JCS 3/15/97) SAFFORD MAR 23, 1997 COTTON PLANTING DATE ADVISORY +-------------------------------------------------------------------------+ | | | v | **************** | ****** 327 ***** | **************** | | ^ normal | | | +---------+---------+---------+---------+---------+---------+---------+---+ 0 200 400 600 800 1000 1200 1400 HEAT UNITS (HU) ACCUMULATED FROM JAN 1 - MAR 22 v = Heat Units accumulated from JAN 1 - MAR 15 PLANTING INFORMATION -------------------------------- The normal temperatures forecast for Monday and Tuesday may lower soil temper- tures below acceptable levels. Growers may wish to delay planting until the above normal temperatures return mid-week. Reminder: a good planting forecast is dry weather with highs above 80F and lows in the upper 40s or higher. WEATHER UPDATE -------------------------------- MAR 23 - MAR 29 WEATHER: WEEKLY HIGH LOW HEAT UNITS 30 yr Norm.: 76 39 55 Last Year : 73 37 44 HUs are running about 3 days ahead of normal. HUs last week = 79. FORECAST: The development of a strong ridge of high pressure over the west coast will send much cooler air into Arizona on Monday and Tuesday. Expect a return to normal late March temperatures early in the week. This cooling trend will be short lived and above normal temperatures are again forecast for the last half of the week. Temperatures should average about 3 degrees above normal for the week; no rainfall is presently forecast through Friday. Last Week's 8am Soil Temp: Max = 57.3 MAR 17 ; Min = 51 MAR 18 AGRONOMY UPDATE -------------------------------- Optimum stand populations for cotton can range from 25,000 to 50,000 plants per acre (ppa) for most varieties. Minimum average populations for cotton are commonly identified at about 20,000 ppa. Adjusting seeding rates during the early stages of planting must take into account a number of factors such as: general seedling vigor of the variety being used, soil temperatures, soil sa- linity, herbicide program, etc.. When faced with more adverse factors, a high- er seeding rate will be needed. For example, if a stand of 40,000 ppa is a target, the variety has 5,000 seeds/pound, a successful emergence rate of 50% would require only 16 lbs. seed/acre. An emergence rate of 25% would re- quire 32 lbs./acre. Adjust seeding rates to field conditions. (JCS 3/22/97) SAFFORD MAR 30, 1997 COTTON PLANTING DATE ADVISORY +-------------------------------------------------------------------------+ | | | v | ******************* | ******** 376 ****** | ******************* | | ^ normal | | | +---------+---------+---------+---------+---------+---------+---------+---+ 0 200 400 600 800 1000 1200 1400 HEAT UNITS (HU) ACCUMULATED FROM JAN 1 - MAR 29 v = Heat Units accumulated from JAN 1 - MAR 22 PLANTING INFORMATION -------------------------------- One of the characteristics common to full season, indeterminate varieties is the tendency to experience increased vegetative growth and reduced yield po- tentials when planted beyond an optimum window. In general, full season vari- eties should be planted before heat unit accumulations after Jan. 1 (HU/Jan.1) extend significantly past 600 to 700. The HU/Jan. 1 accumulations are listed in the figure above for this area. In most parts of central and western AZ, growers should consider planting varieties that are more of a medium maturity type in the near future and make variety selections accordingly. There are a number of excellent varieties in this category to select from which can pro- vide good yield potentials with proper management. (JCS 3/29/97) WEATHER UPDATE -------------------------------- MAR 30 - APR 5 WEATHER: WEEKLY HIGH LOW HEAT UNITS 30 yr Norm.: 76 39 55 Last Year : 77 43 58 HUs are running about 2 days ahead of normal. HUs last week = 50. FORECAST: The main storm track will move into Arizona this week bringing unsettled and much colder weather. Slight chance for rain Monday and again on Wednesday in higher elevation areas. Very windy weather is forecast for early in the week. Temperatures are expected to decline from near normal Monday to more than 10 degrees below normal late in the week. Last Week's 8am Soil Temp: Max = 57.5 MAR 25 ; Min = 50 MAR 27 AGRONOMY UPDATE -------------------------------- Early plantings across the state in recent weeks have resulted in some very strong and healthy stands. It is important to inspect young seedlings, both above and below ground, in an attempt to evaluate overall health and vigor. The hypocotyl tissue (between the point of seed placement and the cotyledons or seed leaves) should be white under the best of circumstances. However, it is not unusual to experience some brown discoloration in this area due to soil salinity, drying, or abrasions (which can occur at the soil line with wind whipping). Tap roots should be extending rapidly at early stages of growth at a rate of approximately 1 in. per day. Tap roots should be approximately 12 in. deep at 1st true leaf and 24 in. by the 2nd to 3rd leaf. (JCS 3/29/97) SAFFORD APR 6, 1997 COTTON PLANTING DATE ADVISORY +-------------------------------------------------------------------------+ | | | v | ********************* | ******** 419 ******** | ********************* | | ^ normal | | | +---------+---------+---------+---------+---------+---------+---------+---+ 0 200 400 600 800 1000 1200 1400 HEAT UNITS (HU) ACCUMULATED FROM JAN 1 - APR 5 v = Heat Units accumulated from JAN 1 - MAR 29 PLANTING INFORMATION -------------------------------- A very sucseptible stage of development for a young cotton seedling is the period immediately following planting. When the seed is placed in the ground it begins absorb (imbibe) water and initiate a rapid increase in metabolic activity. Much of this physiological activity on the part of the seed takes place within the first few hours after planting. It is at this stage when a young seedling is very sensitive to chilling injury. If soil temperatures are 50 F or less while the seed is first imbibing water, severe damage to the seedling can occur, which can negatively affect vigor and enhance the chances for seedling diseases. The seedling continues to be very sensitive to cold soil conditions (less than 55 F) as the roots begin to develop. (JCS 4/5/97) WEATHER UPDATE -------------------------------- APR 6 - APR 12 WEATHER: WEEKLY HIGH LOW HEAT UNITS 30 yr Norm.: 81 42 70 Last Year : 82 43 75 HUs are running about normal. HUs last week = 42. FORECAST: Another significant storm is forecast to impact Arizona this week! Expect sunny and dry weather with near normal temperatures through Wednesday. Unsettled weather will then return Thursday with the arrival of a new storm system. Temperatures are expected to run about 5 degrees below normal late in the week. Slight chance for rain on Thursday and Friday, especially in higher elevation areas and the southeast. Reminder! Good planting weather: sunny with highs above 80F & lows above 48F. Last Week's 8am Soil Temp: Max = 60.1 APR 2 ; Min = 50.9 APR 4 AGRONOMY UPDATE -------------------------------- In the past week, weather conditions have not been at all conducive to plant- ing cotton or improving crop development. Due to these conditions we need to carefully monitor and evaluate crop health. Fields planted within the past week are quite vulnerable to seedling disease. This is particularly true for cases with dry planting and water-up irrigations. For example, with an ex- perimental site in central AZ, the field was dry planted and watered-up on 1 April with alternate row irrigation; air temp. was 72 F at 10 AM, the soil on the dry side of the bed was 68 F, and the wet soil in the seed line was 52 F. At 8 AM on 4/2/97 the wet seed line was 48 F. Fields like this are going to need careful monitoring, and a lot of luck in the next few weeks. (JCS 4/5/97) SAFFORD APR 13, 1997 COTTON PLANTING DATE ADVISORY +-------------------------------------------------------------------------+ | | | v | *********************** | ********** 466 ******** | *********************** | | ^ normal | | | +---------+---------+---------+---------+---------+---------+---------+---+ 0 200 400 600 800 1000 1200 1400 HEAT UNITS (HU) ACCUMULATED FROM JAN 1 - APR 12 v = Heat Units accumulated from JAN 1 - APR 5 PLANTING INFORMATION -------------------------------- With the cool weather we have experienced recently, evaluating field popula- tions and field conditions is important. Young seedlings should be evaluated both above and below ground, in evaluating overall health and vigor. The hypo- cotyl tissue (between the point of seed placement and the cotyledons or seed leaves) should be white under the best of circumstances. However, it is not unusual to experience some slight brown discoloration in this area. The below ground portion of the plant should be checked regularly for the appearance of any disease. Tap roots should be extending rapidly at early stages of growth at a rate of approximately 1 in. per day. Tap roots should be approximately 12 in. deep at 1st true leaf and 24 in. by the 2nd to 3rd leaf. (JCS 4/12/97) WEATHER UPDATE -------------------------------- APR 13 - APR 19 WEATHER: WEEKLY HIGH LOW HEAT UNITS 30 yr Norm.: 83 44 77 Last Year : 82 46 78 HUs are running about 2 days behind normal. HUs last week = 47. FORECAST: A ridge of high pressure will bring sunny and dry weather this week. Temperatures will warm from near normal early in the week to 3-5 degrees above normal by late in the week. Little chance for rain. Last Week's 8am Soil Temp: Max = 58.3 APR 10 ; Min = 50.5 APR 6 AGRONOMY UPDATE -------------------------------- Cotton that has been planted in the past two weeks may have experienced some degree of chilling injury, which can occur when soil temperatures drop to 55 F or less. Plants are particularly susceptible to chilling injury within the first day or so after planting while the seed is imbibing water. Even estab- lished plants can experience a reduction in vigor and increased sucseptibility to seedling diseases under the cool and windy conditions that have been common recently. Under these circumstances, fields should be monitored routinely. Stand counts should be checked in several parts of a field and root condition should be monitored for the development of any seedling disease. Soils should also be monitored for crusting and surface drying. (JCS 4/12/97) SAFFORD APR 20, 1997 COTTON PLANTING DATE ADVISORY +-------------------------------------------------------------------------+ | | | v | *************************** | ************ 539 ********** | *************************** | | ^ normal | | | +---------+---------+---------+---------+---------+---------+---------+---+ 0 200 400 600 800 1000 1200 1400 HEAT UNITS (HU) ACCUMULATED FROM JAN 1 - APR 19 v = Heat Units accumulated from JAN 1 - APR 12 PLANTING INFORMATION -------------------------------- The best potential for optimum growth, development, and yield for full season type varieties is realized if they are planted before annual HU accumulation exceeds the 600-700 range (see figure above). For fields yet to be planted or in replant situations, it is important to shift to more determinate varieties (medium maturity types). Fields replanted in late April should exhibit excellent vigor if the weather remains warm; however, care should be taken to avoid full season varieties which may prove more vulnerable to monsoon heat stress. Field evaluations in the upcoming weeks may reveal cases where replanting is needed; stands that look O.K. now may decline due to weakened root systems. Variety selection will be increasingly important as we approach May 1st. (JCS 4/19/97) WEATHER UPDATE -------------------------------- APR 20 - APR 26 WEATHER: WEEKLY HIGH LOW HEAT UNITS 30 yr Norm.: 83 44 78 Last Year : 91 46 100 HUs are running about 2 days behind normal. HUs last week = 73. FORECAST: A major spring storm system is expected to develop over the Rockies by mid-week! Expect mostly sunny and warm temperatures through Tuesday, followed by signifi- cant cooling later in the week. Temperatures are expected to fall to nearly 10 degrees below normal by Friday. Rainfall is not expected to be heavy with this storm; however, showers are possible on Wednesday and Thursday, especially in higher elevation production areas. Note: this storm has the potential to pro- duce very windy weather. Last Week's 8am Soil Temp: Max = 63.5 APR 19 ; Min = 55.5 APR 13 AGRONOMY UPDATE -------------------------------- In the past few weeks many fields have been subjected to some cool soil temper- atures. Stress from these cool conditions have resulted in some replanting. However, many fields that have been planted and established since about the end of March should be evaluated carefully. It is not uncommon to find a significant number of plants with damaged roots and signs of Rhizoctonia (soreshin), partic- ularly on the hypocotyl areas of the plant (zone between the point of seed placement and the cotyledons). Many of these plants will likely survive, but their health and vigor may be substantially comprimised. Also, plants like these can begin to die and reduce stands if the weather turns hot quickly. More replanting may be needed. (JCS 4/19/97) SAFFORD APR 27, 1997 COTTON PLANTING DATE ADVISORY +-------------------------------------------------------------------------+ | | | v | ******************************* | ************** 619 ************ | ******************************* | | ^ normal | | | +---------+---------+---------+---------+---------+---------+---------+---+ 0 200 400 600 800 1000 1200 1400 HEAT UNITS (HU) ACCUMULATED FROM JAN 1 - APR 26 v = Heat Units accumulated from JAN 1 - APR 19 INSECT UPDATE -------------------------------- Many insects are now in cotton: whiteflies, aphids, mites & thrips; & many beneficials: ladybird & Collops beetles, Geocoris, & aphid parasitoids. Also, many areas have experienced high winds & potentials for sand-blasting may be high. Stands which emerged well, but then experienced 1 or more bouts of cool weather may have thrips damage. Under warm conditions, plants can out-grow this damage; however, severe pressure can result in forking of the plants & delays to maturity. Thrips sprays might be called for in instances where this can be anticipated, but are of relatively less value after the damage is done. Look for thrips including the lighter-colored immature forms & evidence of their feeding such as silvering or crumpling of cotyledons & other leaves. (pce 4/28) WEATHER UPDATE -------------------------------- APR 27 - MAY 3 WEATHER: WEEKLY HIGH LOW HEAT UNITS 30 yr Norm.: 84 46 85 Last Year : 90 48 103 HUs are running about 2 days behind normal. HUs last week = 80. FORECAST: Mostly sunny and warm with periods of windy weather. Storm systems passing north of Arizona will produce winds and some slight cooling Tuesday and Thursday but little chance for precipitation. Temperatures will average 3 degrees above normal for the week. Last Week's 8am Soil Temp: Max = 66.7 APR 24 ; Min = 58.4 APR 25 AGRONOMY UPDATE -------------------------------- With the strong and persitent winds that we have been experiencing across the state in recent weeks, many fields are sustaining damage to leaves, small squares, and terminals. Terminals in small plants (approx. 8 total nodes or less) are particularly sensitive, and can be lost due to wind and sandblasting damage. One easy and generally accurate symptom to look for that indicates terminal damage or loss, consists of an over-elongated petiole of a mainstem leaf, usually about 1 to 2 nodes below the terminal. The petiole will commonly elongate in an exagerated fashion before the splitting of the terminal, which will usually take about 10 days to appear. Some insects can also cause termi- nal or square damage, but the wind is a good candidate now. (JCS 4/26/97) SAFFORD COTTON DEVELOPMENT ADVISORY MAY 4, 1997 PLANTING +/- normal DATE+-------------------------------------------------------------------------+ | | | | | | | | | | v | | | | | | | | 3/15********* 470 0 days | v | | | | | | | | 4/1 ****** 317 -2 days | v | | | | | | | | 4/15***** 227 +1 day | | | | | | | | | 5/1 28 0 days | | | | | | | | | | Pin Sus 1st 1" Pk. Bloom Cut-Out Terminate | | head Sq. Flowr Boll +---+---+ +---+---+ +---+---+ | | S M F S M F S M F | +-------+-------+-------+-------+-------+-------+-------+-------+-------+-+ 0 400 800 1200 1600 2000 2400 2800 3200 3600 HEAT UNITS ACCUMULATED FROM PLANTING to MAY 3 v = Heat Units on APR 26; S,M,F = Short, Medium, and Full Season Varieties INSECT UPDATE -------------------------------- Many insects are now in cotton: whiteflies, aphids, mites & thrips; & many beneficials: ladybird & Collops beetles, Geocoris, & aphid parasitoids. Also, many areas have experienced high winds & potentials for sand-blasting may be high. Stands which emerged well, but then experienced 1 or more bouts of cool weather may have thrips damage. Under warm conditions, plants can out-grow this damage; however, severe pressure can result in forking of the plants & delays to maturity. Thrips sprays might be called for in instances where this can be anticipated, but are of relatively less value after the damage is done. Look for thrips including the lighter-colored immature forms & evidence of their feeding such as silvering or crumpling of cotyledons & other leaves. (pce 5/05) MAY 4 - MAY 10 WEATHER -------------------------------- WEEK HIGH LOW HEAT UNITS 30 yr Norm.: 86 48 94 Last Year : 99 52 122 WEATHER UPDATE, STATISTICS & ESTIMATED COTTON WATER USE -------------------------------------------------------------- A ridge of high pressure will develop over the West bringing mostly sunny and very warm weather to Arizona. Temperatures should run about 5 degrees above normal for the week. Little chance for rain. Spring emergence of PBW should be about 7% complete at this time. Heat Units (HU) are running about 1 day behind normal. HU last week = 97. Heat Unit accumulation since Jan 1 = 717; Last year = 870; 30 year normal = 732. Planting date : 3/15 4/1 4/15 5/1 Water Use (last week): .25" .25" .25" .25" AGRONOMY UPDATE -------------------------------- Terminals of cotton plants that are lost early will commonly result in a delay in early fruiting of about 2 weeks. Fields with sufficient development may be forming the first fruiting branch (FFB), ideally at nodes 5, 6, or 7 above the cotyledons (counted as node = 0). Wind and sandblasting can also cause the early squares to abort. In some cases, plants are not forming FFB until node 8, 9, or higher. All of these conditions can serve as indications of fields that may be early candidates for plant growth regulator applications (ex. PIX) which for best results should be applied if and when changes toward excessive vigor are measured in the field. Thus, fields should be monitored to identify any of these changes and/or tendencies early in the season. (JCS 5/3/97) SAFFORD COTTON DEVELOPMENT ADVISORY MAY 11, 1997 PLANTING +/- normal DATE+-------------------------------------------------------------------------+ | | | | | | | | | | v | | | | | | | | 3/15************ 596 +2 days | v | | | | | | | | 4/1 ********* 443 0 days | v | | | | | | | | 4/15******* 353 +3 days | | | | | | | | | 5/1 *** 154 +2 days | | | | | | | | | | Pin Sus 1st 1" Pk. Bloom Cut-Out Terminate | | head Sq. Flowr Boll +---+---+ +---+---+ +---+---+ | | S M F S M F S M F | +-------+-------+-------+-------+-------+-------+-------+-------+-------+-+ 0 400 800 1200 1600 2000 2400 2800 3200 3600 HEAT UNITS ACCUMULATED FROM PLANTING to MAY 10 v = Heat Units on MAY 3; S,M,F = Short, Medium, and Full Season Varieties INSECT UPDATE -------------------------------- Many insects are now in cotton: whiteflies, aphids, mites & thrips; & many beneficials: ladybird & Collops beetles, Geocoris, & aphid parasitoids. Also, many areas have experienced high winds & potentials for sand-blasting may be high. Stands which emerged well, but then experienced 1 or more bouts of cool weather may have thrips damage. Under warm conditions, plants can out-grow this damage; however, severe pressure can result in forking of the plants & delays to maturity. Thrips sprays might be called for in instances where this can be anticipated, but are of relatively less value after the damage is done. Look for thrips including the lighter-colored immature forms & evidence of their feeding such as silvering or crumpling of cotyledons & other leaves (pce 5/11). MAY 11 - MAY 17 WEATHER -------------------------------- WEEK HIGH LOW HEAT UNITS 30 yr Norm.: 89 50 105 Last Year : 100 59 145 WEATHER UPDATE, STATISTICS & ESTIMATED COTTON WATER USE -------------------------------------------------------------- Partly cloudy and warm with above normal humidity through mid-week. Scattered showers and thunderstorms are possible through Tuesday, especially in central and southeastern production areas and near mountains. Less humid and slightly cooler later in the week. Temperatures should average 3-5 degrees above normal. Spring emergence of PBW should be about 12% complete at this time. Heat Units (HU) are running about 2 days ahead of normal. HU last week = 127. Heat Unit accumulation since Jan 1 = 843; Last year = 992; 30 year normal = 826. Planting date : 3/15 4/1 4/15 5/1 Water Use (last week): .24" .24" .24" .24" AGRONOMY UPDATE -------------------------------- Decisions concerning the timing of the first post-plant irrigation should usually be based on soil-water levels in relation to plant condition. We often find that optimum levels of soil-water depletion for most in-season irriga- tions and the first post-plant irrigation are at about 50% plant-available soil-water. This season we are finding that for many fields the soils are dry- ing out very quickly and the first post-plant irrigation is being required relatively early. There are a number of factors associated with this and each case must be considered on a field by field basis. In many fields the root systems have not developed vigorously and soils are drying out beyond the reach of the active roots, both of which should be monitored. (JCS 5/10/97) SAFFORD COTTON DEVELOPMENT ADVISORY MAY 18, 1997 PLANTING +/- normal DATE+-------------------------------------------------------------------------+ | | | | | | | | | | v | | | | | | | | 3/15*************** 743 +5 days | v | | | | | | | | 4/1 ************ 590 +3 days | v | | | | | | | | 4/15********** 500 +6 days | v | | | | | | | | 5/1 ****** 301 +5 days | | | | | | | | | | Pin Sus 1st 1" Pk. Bloom Cut-Out Terminate | | head Sq. Flowr Boll +---+---+ +---+---+ +---+---+ | | S M F S M F S M F | +-------+-------+-------+-------+-------+-------+-------+-------+-------+-+ 0 400 800 1200 1600 2000 2400 2800 3200 3600 HEAT UNITS ACCUMULATED FROM PLANTING to MAY 17 v = Heat Units on MAY 10; S,M,F = Short, Medium, and Full Season Varieties INSECT UPDATE -------------------------------- PBW moths that emerge now have nowhere to oviposit & will eventually die (suicidal emergence). Susceptible cotton fruit (at 900 HU after planting) is required for PBW survival. Pinhead squares (at 700 HUAP) should be present in the earliest planted fields this week. Flea beetles, beet armyworms, and thrips can damage young plants, but generally do not require remedial treatment. Destruction of key weed species (e.g., London rocket, Chenopodium spp.) can lower the risk of infestation by other pests (e.g., false chinch bug & cotton fleahopper). Bandedwinged WFs are more common in these areas & can be identified by gray bands on their wings and darker bodies (pce 5/18). MAY 18 - MAY 24 WEATHER -------------------------------- WEEK HIGH LOW HEAT UNITS 30 yr Norm.: 92 53 116 Last Year : 95 61 142 WEATHER UPDATE, STATISTICS & ESTIMATED COTTON WATER USE -------------------------------------------------------------- Partly cloudy and warm with above normal humidity this week. Scattered thunder- storms are possible through Wednesday in central and eastern production areas, especially near the mountains. Daytime highs will run near normal while the humidity will keep night temperatures above normal. Temperatures should average about 2 degrees above normal for the week. Spring emergence of PBW should be about 21% complete at this time. Heat Units (HU) are running about 4 days ahead of normal. HU last week = 147. Heat Unit accumulation since Jan 1 = 990; Last year = 1137; 30 year normal = 931. Planting date : 3/15 4/1 4/15 5/1 Water Use (last week): .24" .24" .24" .24" AGRONOMY UPDATE -------------------------------- With many fields transitioning from early vegetative growth to the beginning of the fruiting cyle, it is important to monitor fields to identify the aver- age node for the first fruiting branch (FFB). We would like to see FFBs formed at nodes 5, 6, or 7 (above the cotyledons). If the FFB occurs above node 7, this will indicate a delay in the occurrence of the first bloom and can also possibly indicate early vegetative tendencies. A simple measure of the plant height to node ratio (HNR) can serve as an index of crop vigor, with reference to established baselines for AZ cotton growth. The same is true for early fruit retention counts. If vigor is low, below the middle HNR baseline, avoid any water stress and continue to monitor for changes. (JCS 5/17/97) SAFFORD COTTON DEVELOPMENT ADVISORY MAY 25, 1997 PLANTING +/- normal DATE+-------------------------------------------------------------------------+ | | | | | | | | | | |v | | | | | | | 3/15***************** 859 +4 days | v | | | | | | | | 4/1 ************** 706 +3 days | v | | | | | | | | 4/15************ 616 +5 days | v | | | | | | | | 5/1 ******** 417 +4 days | | | | | | | | | | Pin Sus 1st 1" Pk. Bloom Cut-Out Terminate | | head Sq. Flowr Boll +---+---+ +---+---+ +---+---+ | | S M F S M F S M F | +-------+-------+-------+-------+-------+-------+-------+-------+-------+-+ 0 400 800 1200 1600 2000 2400 2800 3200 3600 HEAT UNITS ACCUMULATED FROM PLANTING to MAY 24 v = Heat Units on MAY 17; S,M,F = Short, Medium, and Full Season Varieties INSECT UPDATE -------------------------------- Pinhead squares (PHS) should be identified in each field (about 700 HU after planting) in order to accurately predict the time of squares which are susceptible to PBW (200 HU after PHS). PBW moths that emerge & have nowhere to oviposit will eventually die (suicidal emergence). Pheromone traps can be used to assess PBW moth pressure generally. PHS treatments for PBW control are unnecessary in Bt cotton. Examine safflower acreage now carefully for Lygus bugs before pre-harvest intervals prevent the use of an insecticide. Manage cuttings of alfalfa NOW (through the period of peak squaring in cotton, next 2 cuttings) such that half-grown hay is always present locally to help prevent Lygus migrations to cotton (i.e., strip or block cut) (pce 5/25/97). MAY 25 - MAY 31 WEATHER -------------------------------- WEEK HIGH LOW HEAT UNITS 30 yr Norm.: 93 54 122 Last Year : 93 52 116 WEATHER UPDATE, STATISTICS & ESTIMATED COTTON WATER USE -------------------------------------------------------------- A ridge of high pressure will bring hot and dry weather to Arizona this week. Expect hot days, mild nights and little chance for rain. Temperatures will average about 4 degrees above normal. No heat stress is expected this week if crops remain well watered. May has produced more clouds, humidity and rain than normal in many areas. An assess- ment of soil moisture status may be therefore be appropriate at this time. Avoid water stress during the primary bloom cycle! Spring emergence of PBW should be about 32% complete at this time. Heat Units (HU) are running about 4 days ahead of normal. HU last week = 115. Heat Unit accumulation since Jan 1 = 1106; Last year = 1279; 30 year normal = 1047. Planting date : 3/15 4/1 4/15 5/1 Water Use (last week): .35" .18" .18" .18" AGRONOMY UPDATE -------------------------------- Strong crop vigor is needed to establish a framework or foundation upon which a good boll load and yield can be developed. If a cotton plant is suffering from low vigor, node production can be reduced, which reduces fruiting sites, which can then reduce yield potential. Excessive vigor can produce plants that are vegetative in nature, which is a problem if fruit retention (FR) is low. We have established baselines in AZ describing normal vigor by use of a height to node ratio (HNR). Baselines for %FR are based on the first 2 fruiting sites on a fruiting branch. Control of excessive vigor with PGR applications (i.e. PIXtm) should be based on crop condition and avoided if vigor is low. Monitor plants directly for HNR and FR status when making mgt. decisions.(JCS 5/24/97) SAFFORD COTTON DEVELOPMENT ADVISORY JUN 1, 1997 PLANTING +/- normal DATE+-------------------------------------------------------------------------+ | | | | | | | | | | | v| | | | | | | 3/15******************** 993 +5 days | v | | | | | | | 4/1 ***************** 840 +3 days | v | | | | | | | | 4/15*************** 750 +6 days | v | | | | | | | | 5/1 *********** 551 +5 days | | | | | | | | | | Pin Sus 1st 1" Pk. Bloom Cut-Out Terminate | | head Sq. Flowr Boll +---+---+ +---+---+ +---+---+ | | S M F S M F S M F | +-------+-------+-------+-------+-------+-------+-------+-------+-------+-+ 0 400 800 1200 1600 2000 2400 2800 3200 3600 HEAT UNITS ACCUMULATED FROM PLANTING to MAY 31 v = Heat Units on MAY 24; S,M,F = Short, Medium, and Full Season Varieties INSECT UPDATE -------------------------------- Pinhead squares (PHS) should be identified in each field (about 700 HU after planting) in order to accurately predict the time of squares which are susceptible to PBW (200 HU after PHS). PBW moths that emerge & have nowhere to oviposit will eventually die (suicidal emergence). Pheromone traps can be used to assess PBW moth pressure generally. PHS treatments for PBW control are unnecessary in Bt cotton. Natural enemies are at high levels in many areas (lacewings, lady beetles, big-eyed bugs, Drapetis flies, pirate bugs). Avoid early season insecticide use, unless indicated by high lygus levels. Flea beetles, false chinch bugs, beet armyworms & white-marked fleahoppers may be present but rarely require control. (pce 6/01/97). JUN 1 - JUN 7 WEATHER -------------------------------- WEEK HIGH LOW HEAT UNITS 30 yr Norm.: 96 55 130 Last Year : 106 63 163 WEATHER UPDATE, STATISTICS & ESTIMATED COTTON WATER USE -------------------------------------------------------------- Hot and dry early in the week with near record daytime temperatures. The ridge of high pressure responsible for the current hot spell is expected to weaken by Thursday bringing a return to normal temperatures and a chance for scattered thunderstorms on Friday. Windy conditions are possible Wednesday & Thursday with this change in weather. Temperatures will run about 6 degrees above normal. No heat stress is expected this week if crops remain well watered. Heat stress problems are rare at this time of year because dry air (low dew points) helps maintain both day and night crop temperatures at optimal levels. Spring emergence of PBW should be about 48% complete at this time. Heat Units (HU) are running about 4 days ahead of normal. HU last week = 134. Heat Unit accumulation since Jan 1 = 1240; Last year = 1395; 30 year normal = 1169. Planting date : 3/15 4/1 4/15 5/1 Water Use (last week): .74" .44" .27" .25" AGRONOMY UPDATE -------------------------------- The most important thing to avoid at this stage in the season (for a cotton crop) is stress, particularly from water. We are moving into a period of the season (June and the time prior to the beginning of a monsoon pattern) that can be the most critical to us in terms of establishing and realizing a good yield potential. Therefore, it is important to monitor each field and deter- mine vigor and fruiting conditions. Height to node ratios (HNR) and fruit re- tention (FR) baselines can be used to assess crop condition. HNR values should be near the middle baseline of the established UA guidelines, with as strong a FR level as possible. If HNRs are low, stress conditions should be evaluated. Prime time is here, push the crop, and set a strong fruit load. (JCS 5/31/97) SAFFORD COTTON DEVELOPMENT ADVISORY JUN 8, 1997 PLANTING +/- normal DATE+-------------------------------------------------------------------------+ | | | | | | | | | | | | v | | | | | | 3/15********************** 1124 +5 days | | v| | | | | | | 4/1 ******************* 971 +3 days | |v | | | | | | | 4/15****************** 881 +5 days | v | | | | | | | | 5/1 ************** 682 +5 days | | | | | | | | | | Pin Sus 1st 1" Pk. Bloom Cut-Out Terminate | | head Sq. Flowr Boll +---+---+ +---+---+ +---+---+ | | S M F S M F S M F | +-------+-------+-------+-------+-------+-------+-------+-------+-------+-+ 0 400 800 1200 1600 2000 2400 2800 3200 3600 HEAT UNITS ACCUMULATED FROM PLANTING to JUN 7 v = Heat Units on MAY 31; S,M,F = Short, Medium, and Full Season Varieties INSECT UPDATE -------------------------------- Pinhead squares (PHS) should be identified in each field (about 700 HU after planting) in order to accurately predict the time of squares which are susceptible to PBW (200 HU after PHS). PBW moths that emerge & have nowhere to oviposit will eventually die (suicidal emergence). Pheromone traps can be used to assess PBW moth pressure generally. PHS treatments for PBW control are unnecessary in Bt cotton. Natural enemies are at high levels in many areas (lacewings, lady beetles, big-eyed bugs, Drapetis flies, pirate bugs). Avoid early season insecticide use, unless indicated by high lygus levels. Flea beetles, false chinch bugs, beet armyworms & white-marked fleahoppers may be present but rarely require control. (pce 6/08/97). JUN 8 - JUN 14 WEATHER -------------------------------- WEEK HIGH LOW HEAT UNITS 30 yr Norm.: 98 57 138 Last Year : 100 68 175 WEATHER UPDATE, STATISTICS & ESTIMATED COTTON WATER USE -------------------------------------------------------------- High pressure will produce sunny and dry weather with near normal temperatures through Thursday. High pressure is expected to weaken on Friday resulting in increased humidity and the chance for scattered thundershowers. Temperatures should average near normal for the week. Spring emergence of PBW should be about 63% complete at this time. Heat Units (HU) are running about 4 days ahead of normal. HU last week = 131. Heat Unit accumulation since Jan 1 = 1371; Last year = 1558; 30 year normal = 1299. Planting date : 3/15 4/1 4/15 5/1 Water Use (last week): .91" .64" .48" .23" AGRONOMY UPDATE -------------------------------- Many fields in this area are in the early parts of the fruiting cycle with early planted fields rapidly progressing towards first bloom. This is when we can begin to realize the benefits from an early planting, with plants fruiting vigorously and the prospects for good weather and production condi- tions ahead for several weeks. Strong vigor and fruit retention (FR) are best encouraged by avoiding stress, particularly water. N fertilization is most efficient if split applications are made at about 50 - 75 lbs. N/acre/applica- tion, and completed by peak bloom (about 2000 - 2200 HUAP). Applying PGRs (i.e. PIXtm) should be restricted to cases of need, such as high or increasing vigor (heigth:node ratios, HNR) and/or low FR. (JCS 6/07/97) SAFFORD COTTON DEVELOPMENT ADVISORY JUN 15, 1997 PLANTING +/- normal DATE+-------------------------------------------------------------------------+ | | | | | | | | | | | | v | | | | | | 3/15************************* 1250 +2 days | | |v | | | | | | 4/1 ********************** 1097 +1 day | | v | | | | | | 4/15******************** 1007 +3 days | v | | | | | | | 5/1 **************** 808 +2 days | | | | | | | | | | Pin Sus 1st 1" Pk. Bloom Cut-Out Terminate | | head Sq. Flowr Boll +---+---+ +---+---+ +---+---+ | | S M F S M F S M F | +-------+-------+-------+-------+-------+-------+-------+-------+-------+-+ 0 400 800 1200 1600 2000 2400 2800 3200 3600 HEAT UNITS ACCUMULATED FROM PLANTING to JUN 14 v = Heat Units on JUN 7; S,M,F = Short, Medium, and Full Season Varieties INSECT UPDATE -------------------------------- Pinhead squares (PHS) should be identified in each field (about 700 HU after planting) in order to accurately predict the time of squares which are susceptible to PBW (200 HU after PHS). PBW moths that emerge & have nowhere to oviposit will eventually die (suicidal emergence). Pheromone traps can be used to assess PBW moth pressure generally. PHS treatments for PBW control are unnecessary in Bt cotton. Natural enemies are at high levels in many areas (lacewings, lady beetles, big-eyed bugs, Drapetis flies, pirate bugs). Avoid early season insecticide use, unless indicated by high lygus levels. Flea beetles, false chinch bugs, beet armyworms & white-marked fleahoppers may be present but rarely require control. (pce 6/15/97). JUN 15 - JUN 21 WEATHER -------------------------------- WEEK HIGH LOW HEAT UNITS 30 yr Norm.: 102 60 151 Last Year : 106 64 167 WEATHER UPDATE, STATISTICS & ESTIMATED COTTON WATER USE -------------------------------------------------------------- Mostly sunny with warm days and mild nights. Temperatures should run about 2 degrees above normal for the week. Little chance for rain in central and western areas; slight chance for showers in southeastern areas late in the week. Cool June weather does not mean reduced crop water use. Solar radiation (SR) is the main factor driving crop water use and recent cool, dry weather makes for intense SR. Monitor soil moisture and avoid water stress during flowering. Spring emergence of PBW should be about 76% complete at this time. Heat Units (HU) are running about 2 days ahead of normal. HU last week = 126. Heat Unit accumulation since Jan 1 = 1497; Last year = 1733; 30 year normal = 1438. Planting date : 3/15 4/1 4/15 5/1 Water Use (last week): 1.07" .81" .67" .33" AGRONOMY UPDATE -------------------------------- Fields planted through late April should be squaring vigorously by now. Taking into account the first fruiting sites on all fruiting branches present, we would like to see at least about 75-80% fruit retention (FR) levels at this stage. It is important to evaluate plant vigor and FR. Plant vigor can be most easily evaluated by use of a height:node ratio (HNR). Good irrigation manage- ment (no stress) and N fertilization serve as the best tools for stimulating growth and strong vigor. In fields with low FR where insects are not a problem, square abortion rates could be due to wind and square dessication. If HNRs are increasing (>1.0) and FR levels are low, PGR applications may need to be con- sidered. Split applications of N (40-70 lbs. N/acre) are best (JCS 6/14/97). SAFFORD COTTON DEVELOPMENT ADVISORY JUN 22, 1997 PLANTING +/- normal DATE+-------------------------------------------------------------------------+ | | | | | | | | | | | | |v | | | | | 3/15**************************** 1399 +3 days | | | v | | | | | | 4/1 ************************* 1246 +2 days | | | v | | | | | | 4/15*********************** 1156 +4 days | | v | | | | | | | 5/1 ******************* 957 +3 days | | | | | | | | | | Pin Sus 1st 1" Pk. Bloom Cut-Out Terminate | | head Sq. Flowr Boll +---+---+ +---+---+ +---+---+ | | S M F S M F S M F | +-------+-------+-------+-------+-------+-------+-------+-------+-------+-+ 0 400 800 1200 1600 2000 2400 2800 3200 3600 HEAT UNITS ACCUMULATED FROM PLANTING to JUN 21 v = Heat Units on JUN 14; S,M,F = Short, Medium, and Full Season Varieties INSECT UPDATE -------------------------------- Sweep cotton & check for the presence of Lygus, WFs, other pests & beneficials. Once sweeps detect WFs, begin leaf-turn samples for SWF adults/leaf & large nymphs/disk on the 5th mainstem leaf below the terminal. Look for Drapetis, a small predaceous fly, present in many area fields. Distinguish this fly from leafminer by a shiny black prothorax, the lack of yellow markings & a smaller head. As alfalfa is cut, Lygus adults can move to squaring cotton. Check cotton carefully adjacent to newly-cut alfalfa for Lygus numbers & fruit retention. Manage cuttings of alfalfa NOW (through peak squaring in cotton, next 2 cuttings) such that half-grown hay is always present locally to help prevent Lygus migrations to cotton (i.e., strip or block cut) (pce 6/22/97). JUN 22 - JUN 28 WEATHER -------------------------------- WEEK HIGH LOW HEAT UNITS 30 yr Norm.: 103 63 161 Last Year : 97 61 151 WEATHER UPDATE, STATISTICS & ESTIMATED COTTON WATER USE -------------------------------------------------------------- Sunny and dry weather with hot days and mild nights. Little chance for rain in western production areas; slight chance for rain in the higher elevation areas of southeast AZ. Warm and dry weather is considered ideal for cotton. Heat stress is unlikely as long as humidity remains low and the crop remains well watered. It appears we will have at least one more week of good cotton weather before any significant moisture enters the state. However, the forecast for late this week shows some moisture leaking into southeast AZ. The normal first appearance of monsoon moisture is the July 5-10, depending on location. Spring emergence of PBW should be about 86% complete at this time. Heat Units (HU) are running about 3 days ahead of normal. HU last week = 140. Heat Unit accumulation since Jan 1 = 1646; Last year = 1900; 30 year normal = 1588. Planting date : 3/15 4/1 4/15 5/1 Water Use (last week): 1.58" 1.27" 1.09" .69" AGRONOMY UPDATE -------------------------------- Fields should have the first blooms by the time they reach approximately 1200 heat units accumulated since planting (HUAP). At this stage of development we would like to see about 75 - 80% fruit retention (FR), first two fruiting positions. The number of nodes above the top white flower (NAWF) should be about 9 to 11 at first bloom. If the NAWF is <9 at first bloom this could be due to low vigor conditions, which can be checked with a height to node ratio (HNR). HNR values at first bloom should be about 1.2. If FR and HNRs are low, plant vigor is needed, requiring good irrigation (no stress) and fertilization management. Splitting applications of N (about 50 lbs. N/acre/app.) based upon crop conditions provides good efficiency and control. (JCS 6/21/97) SAFFORD COTTON DEVELOPMENT ADVISORY JUN 29, 1997 PLANTING +/- normal DATE+-------------------------------------------------------------------------+ | | | | | | | | | | | | | v | | | | | 3/15******************************* 1542 +2 days | | | |v | | | | | 4/1 **************************** 1389 +1 day | | | v| | | | | | 4/15************************** 1299 +3 days | | |v | | | | | | 5/1 ********************** 1100 +2 days | | | | | | | | | | Pin Sus 1st 1" Pk. Bloom Cut-Out Terminate | | head Sq. Flowr Boll +---+---+ +---+---+ +---+---+ | | S M F S M F S M F | +-------+-------+-------+-------+-------+-------+-------+-------+-------+-+ 0 400 800 1200 1600 2000 2400 2800 3200 3600 HEAT UNITS ACCUMULATED FROM PLANTING to JUN 28 v = Heat Units on JUN 21; S,M,F = Short, Medium, and Full Season Varieties INSECT UPDATE -------------------------------- Sweep for Lygus; treat if there are 15-20 total Lygus/100 sweeps. Fields near recently cut alfalfa may harbor high, yet temporary, populations of adults. Check for nymphs & survey for damaged squares (25%) before treating. WFs may be found in fields via sweepnet. Confirm their ID & start leaf-turn sampling. 3 species may be present: greenhouse (pupae: long hairs; adults: overlapping wings), bandedwinged (darker pupae: short fringe; adults: bands) & sweetpotato (naked pupae; adults: yellow bodies & slightly parted wings). Consider IGRs when there are 3-5 adults per leaf & 1 large, visible nymph per disk on the 5th main stem leaf below the terminal OR 39-57% infested leaves (with 3 or more adults) & 40% infested disks (with 1 or more nymphs) in 30 samples (pce 6/29). JUN 29 - JUL 5 WEATHER -------------------------------- WEEK HIGH LOW HEAT UNITS 30 yr Norm.: 102 66 168 Last Year : 102 72 184 WEATHER UPDATE, STATISTICS & ESTIMATED COTTON WATER USE -------------------------------------------------------------- Sunny with hot days and mild nights. Little chance for rain. Daytime tempera- tures near or above 110 F are expected in central and western production areas this week. Heat stress, however, should not be a problem due very low humidity. Avoid water stress! Water stress reduces photosynthesis and increases daytime heat stress, resulting in lower fruit retention and early cut-out. The forecast indicates the monsoon will not arrive this week. Long-term records indicate the normal monsoon arrival date is next week (5-10 July). Spring emergence of PBW should be about 93% complete at this time. Heat Units (HU) are running about 2 days ahead of normal. HU last week = 145. Heat Unit accumulation since Jan 1 = 1789; Last year = 2051; 30 year normal = 1750. Planting date : 3/15 4/1 4/15 5/1 Water Use (last week): 1.86" 1.55" 1.37" .98" AGRONOMY UPDATE -------------------------------- Many fields in this area are progressing into early bloom and generally con- tinuing to show increases in fruit retention (FR), which is very encouraging to see. Crop vigor has generally been increasing for many fields as well. The additional canopy development is positive in that it increases plant leaf area and the photosynthetically active leaves needed to support an increasing fruit load. For strong FR and vigor it is very important to avoid any water stress. It is important to check fields for FR and vigor (height:node ratios, HNR) and to detect any changes. PIXtm may be needed if HNRs are increasing and FR is dropping. Split N applications as needed; following FR, vigor, and plant N status (petioles), until peak bloom (2000 HUAP). (JCS 6/28/97) SAFFORD COTTON DEVELOPMENT ADVISORY JUL 6, 1997 PLANTING +/- normal DATE+-------------------------------------------------------------------------+ | | | | | | | | | | | | | v | | | | 3/15********************************** 1699 +2 days | | | | v | | | | | 4/1 ******************************* 1546 +1 day | | | | v | | | | | 4/15***************************** 1456 +2 days | | | v | | | | | | 5/1 ************************* 1257 +2 days | | | | | | | | | | Pin Sus 1st 1" Pk. Bloom Cut-Out Terminate | | head Sq. Flowr Boll +---+---+ +---+---+ +---+---+ | | S M F S M F S M F | +-------+-------+-------+-------+-------+-------+-------+-------+-------+-+ 0 400 800 1200 1600 2000 2400 2800 3200 3600 HEAT UNITS ACCUMULATED FROM PLANTING to JUL 5 v = Heat Units on JUN 28; S,M,F = Short, Medium, and Full Season Varieties INSECT UPDATE -------------------------------- Sweep for Lygus; treat if there are 15-20 total Lygus/100 sweeps. Fields near recently cut alfalfa may harbor high, yet temporary, populations of adults. Check for nymphs & survey for damaged squares (25%) before treating. WFs may be found in fields via sweepnet. Confirm their ID & start leaf-turn sampling. 3 species may be present: greenhouse (pupae: long hairs; adults: overlapping wings), bandedwinged (darker pupae: short fringe; adults: bands) & sweetpotato (naked pupae; adults: yellow bodies & slightly parted wings). Consider IGRs when there are 3-5 adults per leaf & 1 large, visible nymph per disk on the 5th main stem leaf below the terminal OR 39-57% infested leaves (with 3 or more adults) & 40% infested disks (with 1 or more nymphs) in 30 samples (pce 7/6). JUL 6 - JUL 12 WEATHER -------------------------------- WEEK HIGH LOW HEAT UNITS 30 yr Norm.: 101 67 172 Last Year : 99 72 184 WEATHER UPDATE, STATISTICS & ESTIMATED COTTON WATER USE -------------------------------------------------------------- Mostly sunny and hot with increasing humidity. Slight chance for showers in southeast production areas. Temperature will run about 3F above normal. Humidity (dew point) levels are expected to increase to monsoon level by mid-week (above 55F), bringing the first chance for heat stress this season. Dew point levels forecast for this week can produce Level 1 heat stress when high temperatures exceed 110F and lows remain above 77F. Level 1 heat stress produces low to moderate loss of young (3 day old) bolls. Spring emergence of PBW should be about 96% complete at this time. Heat Units (HU) are running about 2 days ahead of normal. HU last week = 156. Heat Unit accumulation since Jan 1 = 1946; Last year = 2235; 30 year normal = 1918. Planting date : 3/15 4/1 4/15 5/1 Water Use (last week): 2.42" 2.08" 1.88" 1.43" AGRONOMY UPDATE -------------------------------- Fruit retention (FR) and crop vigor have both shown improvements in the past couple of weeks, increasing the current fruiting potential of the crop. At first bloom FR should be about 75 - 80% and at peak bloom (approx. 2000 HUAP), we would like to see FR levels at about 65 - 70% or more (first two positions, all fruiting branches). Increasing vigor can be a good sign for many fields, but if vigor is increasing too fast, PIXtm applications may be in order. Vigor is most easily measured by use of a height:node ratio (HNR) with reference to AZ baselines. PIXtm applications are most effective if HNRs are increasing and FR is low or dropping. Water use rates are increasing, good irrigation manage- ment (no water stress) is critical to realizing crop potential. (JCS 7/5/97) SAFFORD COTTON DEVELOPMENT ADVISORY JUL 13, 1997 PLANTING +/- normal DATE+-------------------------------------------------------------------------+ | | | | | | | | | | | | | | v | | | | 3/15************************************* 1853 +1 day | | | | v | | | | 4/1 ********************************** 1700 0 days | | | | v | | | | | 4/15******************************** 1610 +2 days | | | |v | | | | | 5/1 **************************** 1411 +1 day | | | | | | | | | | Pin Sus 1st 1" Pk. Bloom Cut-Out Terminate | | head Sq. Flowr Boll +---+---+ +---+---+ +---+---+ | | S M F S M F S M F | +-------+-------+-------+-------+-------+-------+-------+-------+-------+-+ 0 400 800 1200 1600 2000 2400 2800 3200 3600 HEAT UNITS ACCUMULATED FROM PLANTING to JUL 12 v = Heat Units on JUL 5; S,M,F = Short, Medium, and Full Season Varieties INSECT UPDATE -------------------------------- Sweep for Lygus; treat if there are 15-20 total Lygus/100 sweeps. Fields near recently cut alfalfa may harbor high, yet temporary, populations of adults. Check for nymphs & survey for damaged squares (25%) before treating. Do NOT confuse cotton fleahopper nymphs (finely speckled antennae, legs & body) with Lygus nymphs (last antennal segment dark). White-marked fleahopper nymphs may also be abundant, but rarely achieve pest status & are distinguished from small Lygus nymphs by having darker green bodies, thicker hind femurs, uniformly green antennae, & well-developed wing pads (relative to their body size). WFs may be found in fields via sweepnet. Confirm their ID & start leaf-turn sampling. Beneficials can help delay WF & other pest populations (pce 7/13). JUL 13 - JUL 19 WEATHER -------------------------------- WEEK HIGH LOW HEAT UNITS 30 yr Norm.: 100 68 173 Last Year : 99 70 176 WEATHER UPDATE, STATISTICS & ESTIMATED COTTON WATER USE -------------------------------------------------------------- Mostly sunny & hot with below normal humidity early in the week. Higher humidity is expected later in the week along with increased shower activity in southeast & near the mountains. Temperatures will run about 3F above normal. Monsoon Update: The first surge of monsoon humidity entered AZ early last week. Fortunately, dew points remained moderate and dry air returned by week's end. The 1997 crop continues to experience little heat stress; crop temperature models indicate Yuma reached the Level 1 heat stress range on 2 days last week. Other production areas avoided heat stress. Higher humidity late this week may pro- duce heat stress in both western & central production areas. Heat Units (HU) are running about 1 day ahead of normal. HU last week = 155. Heat Unit accumulation since Jan 1 = 2100; Last year = 2419; 30 year normal = 2090. Planting date : 3/15 4/1 4/15 5/1 Water Use (last week): 2.38" 2.09" 1.91" 1.53" AGRONOMY UPDATE -------------------------------- Many fields in this area are in the early parts of the fruiting cycle with early planted fields blooming vigorously. At this time in the season we can begin to realize the benefits from an early planting, with plants flower- ing and establishing a boll load. Every day of good weather and production conditions need to taken advantage of. Strong vigor and fruit retention (FR) are best encouraged by avoiding stress, particularly water. N fertilization is most efficient if split applications are made at about 50 - 75 lbs. N/acre/ap- plication, and completed by peak bloom (about 2000 - 2200 HUAP). Applying PGRs (i.e. PIXtm) should be restricted to cases of need, such as high or increasing vigor (height:node ratios, HNR) and/or low FR. (JCS 7/11/97) SAFFORD COTTON DEVELOPMENT ADVISORY JUL 20, 1997 PLANTING +/- normal DATE+-------------------------------------------------------------------------+ | | | | | | | | | | | | | | v | | | | 3/15**************************************** 2022 +1 day | | | | | v | | | | 4/1 ************************************* 1869 0 days | | | | |v | | | | 4/15************************************ 1779 +2 days | | | | v | | | | | 5/1 ******************************** 1580 +1 day | | | | | | | | | | Pin Sus 1st 1" Pk. Bloom Cut-Out Terminate | | head Sq. Flowr Boll +---+---+ +---+---+ +---+---+ | | S M F S M F S M F | +-------+-------+-------+-------+-------+-------+-------+-------+-------+-+ 0 400 800 1200 1600 2000 2400 2800 3200 3600 HEAT UNITS ACCUMULATED FROM PLANTING to JUL 19 v = Heat Units on JUL 12; S,M,F = Short, Medium, and Full Season Varieties INSECT UPDATE -------------------------------- Sweep for Lygus; treat if there are 15-20 total Lygus/100 sweeps. Fields near recently cut alfalfa may harbor high, yet temporary, populations of adults. Check for nymphs & survey for damaged squares (25%) before treating. Do NOT confuse cotton fleahopper nymphs (finely speckled antennae, legs & body) with Lygus nymphs (last antennal segment dark). White-marked fleahopper nymphs may also be abundant, but rarely achieve pest status & are distinguished from small Lygus nymphs by having darker green bodies, thicker hind femurs, uniformly green antennae, & well-developed wing pads (relative to their body size). WFs may be found in fields via sweepnet. Confirm their ID & start leaf-turn sampling. Beneficials can help delay WF & other pest populations (pce 7/20). JUL 20 - JUL 26 WEATHER -------------------------------- WEEK HIGH LOW HEAT UNITS 30 yr Norm.: 99 68 171 Last Year : 102 72 184 WEATHER UPDATE, STATISTICS & ESTIMATED COTTON WATER USE -------------------------------------------------------------- Monsoon conditions will prevail in most production areas this week. Expect more clouds, higher dew points & scattered thundershowers. Higher humidity will push night temperatures above normal, but keep day temperatures at or slightly below normal. Forecasted dew points may produce Level 1 heat stress in central & west- ern areas when low temperatures remain above 77F and highs exceed 105F. Cotton is most sensitive to Level 1 stress at peak bloom. Level 1 heat stress causes low-moderate loss of small bolls (3 dys post bloom) & smaller bolls. Analysis of AZMET weather data indicates that heat stress has not been much of a problem in 1997. Yuma has registered 3 marginal Level 1 stress days in July. Other low elevation areas experienced the first Level 1 stress day late last week. Heat Units (HU) are running about 1 day ahead of normal. HU last week = 169. Heat Unit accumulation since Jan 1 = 2269; Last year = 2595; 30 year normal = 2263. Planting date : 3/15 4/1 4/15 5/1 Water Use (last week): 2.38" 2.12" 1.96" 1.63" AGRONOMY UPDATE -------------------------------- General crop conditions have continued to improve over the past several weeks with good fruit retention (FR) levels. In some cases FR is strong and vigor is relatively low. However, conditions can change very quickly, and therefore, it is best to watch fields and monitor them for any changes in FR and/or vigor (height:node ratios, HNR). Counting the number of nodes above the top (first position)white flower (NAWF) is an easy measure of stage of growth. NAWF counts should be about 7 at peak bloom (approx. 2000 HUAP). Applications of fertilizer N should be completed by peak bloom (approx. 50 lb. N/acre/app.). In all cases good water management (no water stress) is critical. If FR is dropping and HNRs increasing, consider PIXtm applications. (JCS 7/19/97) SAFFORD COTTON DEVELOPMENT ADVISORY JUL 27, 1997 PLANTING +/- normal DATE+-------------------------------------------------------------------------+ | | | | | | | | | | | | | | v| | | | 3/15******************************************** 2192 +1 day | | | | | v | | | | 4/1 ***************************************** 2039 0 days | | | | | v | | | | 4/15*************************************** 1949 +2 days | | | | |v | | | | 5/1 *********************************** 1750 +1 day | | | | | | | | | | Pin Sus 1st 1" Pk. Bloom Cut-Out Terminate | | head Sq. Flowr Boll +---+---+ +---+---+ +---+---+ | | S M F S M F S M F | +-------+-------+-------+-------+-------+-------+-------+-------+-------+-+ 0 400 800 1200 1600 2000 2400 2800 3200 3600 HEAT UNITS ACCUMULATED FROM PLANTING to JUL 26 v = Heat Units on JUL 19; S,M,F = Short, Medium, and Full Season Varieties INSECT UPDATE -------------------------------- INSECT GROWTH REGULATORS (IGRs) have been issued time-limited tolerances for cotton by the Environmental Protection Agency in support of Arizona's & California's Section 18 emergency exemption requests. In EPA's final rule, they state, "Consistent with the need to move quickly on the emergency exemption in order to address an urgent non-routine situation and to ensure that the resulting food is safe and lawful, EPA is issuing this tolerance as provided in section 408 (1)(6)." In short, tolerances have been established for both Applaud & Knack. Lawful use of these IGRs should provide for legal & unrestricted commerce of our cotton crop. IGRs are powerful, effective anti-WF agents that are selective & relatively safe to natural enemies (pce 7/27). JUL 27 - AUG 2 WEATHER -------------------------------- WEEK HIGH LOW HEAT UNITS 30 yr Norm.: 98 68 172 Last Year : 100 70 181 WEATHER UPDATE, STATISTICS & ESTIMATED COTTON WATER USE -------------------------------------------------------------- Partly cloudy with normal temperatures and moderate humidity this week. Chance for scattered thunderstorms each day. Dew point temperatures will run above 60F at many locations this week, bringing a chance for Level 1 heat stress when highs exceed 105F and lows exceed 77F. Level 1 heat stress results in low to moderate loss of small bolls (3 dys post bloom) and smaller harvestable bolls. Level 2 heat stress--characterized by malformed flowers and heavy loss of small bolls--may occur this week if highs approach 110F and lows remain in the 80s. Level 1 stress conditions developed in Yuma & central production areas late last week. Below normal humidity minimized heat stress at Parker & Mohave Valley. Heat Units (HU) are running about 1 day ahead of normal. HU last week = 169. Heat Unit accumulation since Jan 1 = 2439; Last year = 2779; 30 year normal = 2434. Planting date : 3/15 4/1 4/15 5/1 Water Use (last week): 2.09" 2.08" 1.94" 1.65" AGRONOMY UPDATE -------------------------------- Variety tests are one means of evaluating variety adaptation and performance, which has been an important issue in AZ recently. This is an excellent time of the season to compare and evaluate various varieties grown in a side by side setting. The University of Arizona is conducting 11 Upland variety tests at various locations across the state, comparing 10 to 14 varieties at each lo- cation on grower-cooperator fields, in replicated strip tests. I encourage anyone interested to contact your local county Extension agent, find out where a variety test is located in your area, get a plot plan, visit the site, and evaluate and compare variety conditions at present. It is also a good idea to check back periodically with the test between now and harvest. (JCS 7/26/97) SAFFORD COTTON DEVELOPMENT ADVISORY AUG 3, 1997 PLANTING +/- normal DATE+-------------------------------------------------------------------------+ | | | | | | | | | | | | | | | v | | | 3/15*********************************************** 2359 +1 day | | | | | v | | | 4/1 ******************************************** 2206 0 days | | | | | v | | | | 4/15****************************************** 2116 +1 day | | | | | v | | | | 5/1 ************************************** 1917 +1 day | | | | | | | | | | Pin Sus 1st 1" Pk. Bloom Cut-Out Terminate | | head Sq. Flowr Boll +---+---+ +---+---+ +---+---+ | | S M F S M F S M F | +-------+-------+-------+-------+-------+-------+-------+-------+-------+-+ 0 400 800 1200 1600 2000 2400 2800 3200 3600 HEAT UNITS ACCUMULATED FROM PLANTING to AUG 2 v = Heat Units on JUL 26; S,M,F = Short, Medium, and Full Season Varieties INSECT UPDATE -------------------------------- Late season pest management decisions depend greatly on production goals. From peak bloom to cut-out, returns on pest control inputs can decline. While late season insect threats are high, the proportion of the crop protected from injury declines. Thresholds for PBW, Lygus & other yield-limiting pests increase as the crop secures the majority of its yield component (1st cycle set). Exceptions to this include insects that reduce quality or interfere with timely & efficient defoliation. WFs & aphids are 2 pests which require control late in the season to prevent unacceptable losses in quality. Assess your yield goals and days to irrigation & chemical termination. Carefully weigh the costs of additional inputs with your potential gains in yield or quality (pce 8/3/97) AUG 3 - AUG 9 WEATHER -------------------------------- WEEK HIGH LOW HEAT UNITS 30 yr Norm.: 100 68 172 Last Year : 97 66 165 WEATHER UPDATE, STATISTICS & ESTIMATED COTTON WATER USE -------------------------------------------------------------- Monsoon moisture combined with above normal temperatures will make for an un- comfortable week. Expect temperatures to run about 3F above normal and dew points to average above 60F at most locations--a situation that should generate heat stress (HS) conditions in low elevation areas. Level 1 HS (low-moderate loss of 3dy old bolls) is likely in central & western areas, with Level 2 HS (heavy loss of 3dy old bolls) possible along the Colorado River. Crop response to HS is often delayed because HS damages squares. Damaged squares will still flower, but the fruiting structure aborts shortly after bloom. Major shedding events often are delayed 5-10 days after the HS event. Fortunately, much of the 1997 crop is now beyond the most vulnerable stage--peak squaring to peak bloom. Heat Units (HU) are running about 1 day ahead of normal. HU last week = 168. Heat Unit accumulation since Jan 1 = 2606; Last year = 2960; 30 year normal = 2605. Planting date : 3/15 4/1 4/15 5/1 Water Use (last week): 1.87" 1.87" 1.87" 1.7" AGRONOMY UPDATE -------------------------------- As many fields in this area are moving beyond peak bloom (approx. 2000+ HUAP), it is important to monitor fields for fruit retention (FR) and vigor and watch for any changes. For example, at peak bloom we would like to see FR levels at about 65-70% or more (first two positions, all fruiting branches). Increasing vigor can be a good sign for some fields, but if vigor is increasing too fast, PIXtm applications may be appropriate. Vigor is most easily measured by use of a height:node ratio (HNR) with reference to AZ baselines. PIXtm applications are most effective if HNRs are increasing and FR is low or dropping, which can be identified with regular monitoring. Good irrigation management (no water stress) is critical to realizing full crop potentials. (JCS 8/2/97) SAFFORD COTTON DEVELOPMENT ADVISORY AUG 10, 1997 PLANTING +/- normal DATE+-------------------------------------------------------------------------+ | | | | | | | | | | | | | | | v | | | 3/15*************************************************** 2531 +1 day | | | | | | v | | | 4/1 ************************************************ 2378 0 days | | | | | |v | | | 4/15********************************************** 2288 +1 day | | | | | v | | | | 5/1 ****************************************** 2089 +1 day | | | | | | | | | | Pin Sus 1st 1" Pk. Bloom Cut-Out Terminate | | head Sq. Flowr Boll +---+---+ +---+---+ +---+---+ | | S M F S M F S M F | +-------+-------+-------+-------+-------+-------+-------+-------+-------+-+ 0 400 800 1200 1600 2000 2400 2800 3200 3600 HEAT UNITS ACCUMULATED FROM PLANTING to AUG 9 v = Heat Units on AUG 2; S,M,F = Short, Medium, and Full Season Varieties INSECT UPDATE -------------------------------- WFs are sampled on the 5th mainstem leaf below the terminal. Measure both adults & nymphs there to properly time IGR sprays. That is when 39-57% leaves with 3 or more WF adults (12-17 leaves out of 30) AND 40% leaf disks (quarter- size) with 1 or more large visible nymphs (12 out of 30 disks). These methods approximate densities of 3-5 adults/leaf & 1 large nymph/disk. Avoid non-IGR sprays for WFs until fields exceed the threshold (>5 adults/leaf). Beneficials can help delay WF populations. Sweep for Lygus; treat if there are 15-20 total Lygus/100 sweeps. Check for nymphs & survey for damaged squares (25%) before treating. Do NOT confuse cotton fleahopper nymphs (finely speckled antennae, legs & body) with Lygus nymphs (last antennal segment dark) (pce 8/10). AUG 10 - AUG 16 WEATHER -------------------------------- WEEK HIGH LOW HEAT UNITS 30 yr Norm.: 98 66 166 Last Year : 102 66 173 WEATHER UPDATE, STATISTICS & ESTIMATED COTTON WATER USE -------------------------------------------------------------- Mostly sunny and less humid with normal temperatures through mid-week. Higher humidity is forecast by late in the week, though dewpoints (Td) are not expected to increase to the high levels experienced last week. Last week's combination of high temperatures and Td produced heat stress (HS) conditions in many central and western locations. Fortunantely, much of the crop is beyond the critical peak bloom stage. HS in 1997 (# of days) is running at 1/3 of 1996 levels. Heat Units (HU) are running normal. HU last week = 171. Heat Unit accumulation since Jan 1 = 2778; Last year = 3125; 30 year normal = 2778. Planting date : 3/15 4/1 4/15 5/1 Water Use (last week): 1.65" 1.65" 1.65" 1.65" AGRONOMY UPDATE -------------------------------- Peak bloom (PB)should occur at about 2000 to 2200 HUAP. Counting the number of nodes above the top (first position) white flower (NAWF) is an easy measure to assess crop growth stage. At first bloom NAWF should be 9-11, about 7 at peak bloom, and 5 or less toward cut-out. If NAWF counts are below these values at these stages of growth, the crop vigor (height:node ratio, HNR) and fruit re- tention (FR) should be evaluated. NAWF values lower than these normal levels can indicate low vigor and early progession towards cut-out. At this stage we should push for strong vigor (good water mgt.) and complete fertilizer N ap- plications by PB. This is also an important period in the season to watch for any changes in crop vigor (HNR) or FR levels which may occur. (JCS 8/9/97) SAFFORD COTTON DEVELOPMENT ADVISORY AUG 17, 1997 PLANTING +/- normal DATE+-------------------------------------------------------------------------+ | | | | | | | | | | | | | | | v | | | 3/15****************************************************** 2696 +1 day | | | | | | v | | | 4/1 *************************************************** 2543 -1 day | | | | | | v | | | 4/15************************************************* 2453 +1 day | | | | | |v | | | 5/1 ********************************************* 2254 +1 day | | | | | | | | | | Pin Sus 1st 1" Pk. Bloom Cut-Out Terminate | | head Sq. Flowr Boll +---+---+ +---+---+ +---+---+ | | S M F S M F S M F | +-------+-------+-------+-------+-------+-------+-------+-------+-------+-+ 0 400 800 1200 1600 2000 2400 2800 3200 3600 HEAT UNITS ACCUMULATED FROM PLANTING to AUG 16 v = Heat Units on AUG 9; S,M,F = Short, Medium, and Full Season Varieties INSECT UPDATE -------------------------------- WFs are sampled on the 5th mainstem leaf below the terminal. Measure both adults & nymphs there to properly time IGR sprays. That is when 39-57% leaves with 3 or more WF adults (12-17 leaves out of 30) AND 40% leaf disks (quarter- size) with 1 or more large visible nymphs (12 out of 30 disks). These methods approximate densities of 3-5 adults/leaf & 1 large nymph/disk. Avoid non-IGR sprays for WFs until fields exceed the threshold (>5 adults/leaf). Beneficials can help delay WF populations. Sweep for Lygus; treat if there are 15-20 total Lygus/100 sweeps. Check for nymphs & survey for damaged squares (25%) before treating. Do NOT confuse cotton fleahopper nymphs (finely speckled antennae, legs & body) with Lygus nymphs (last antennal segment dark) (pce 8/17). AUG 17 - AUG 23 WEATHER -------------------------------- WEEK HIGH LOW HEAT UNITS 30 yr Norm.: 98 65 164 Last Year : 95 66 166 WEATHER UPDATE, STATISTICS & ESTIMATED COTTON WATER USE -------------------------------------------------------------- Mostly sunny, warm & humid with a chance for afternoon thunderstorms. Expect temperature & humidity to average near normal. Normal mid-August weather con- ditions --hot & humid weather-- often produce cotton heat stress (HS). Level 1 HS (low-moderate loss of 3dy old bolls) is possible in central & western areas this week; level 2 HS (heavy loss of 3dy old bolls) may develop along the Color- ado River. Thus far, August has produced a significant number of HS days in central & west- ern production areas. August HS days for selected locations: Yuma=13; Roll=12; Parker=11; Mohave=8; Laveen=11; Maricopa=11; Paloma=11; Marana=5. Heat Units (HU) are running normal. HU last week = 165. Heat Unit accumulation since Jan 1 = 2943; Last year = 3298; 30 year normal = 2943. Planting date : 3/15 4/1 4/15 5/1 Water Use (last week): 1.98" 1.98" 1.98" 1.98" AGRONOMY UPDATE -------------------------------- The time when the last set of blooms that have a good chance of maturing to a harvestable boll is rapidly approaching in high elevation areas. Of course this will depend on a number of factors such as: the occurrence of the first frost, weather patterns from August-October, crop vigor/rate of senescence (aging), and insect pressure. Crop vigor will be dependent upon the variety, fruit retention (FR) levels, fertility status, and stresses the plant has ex- perienced through the season. Crop condition should be monitored routinely in- cluding vigor (height:node ratio), FR, and growth stage. Growth stage can be easily monitored by counting the nodes above the top (first position) white flower (NAWF 7 at peak bloom and 5 or less near cut-out). JCS 8/16/97 SAFFORD COTTON DEVELOPMENT ADVISORY AUG 24, 1997 PLANTING +/- normal DATE+-------------------------------------------------------------------------+ | | | | | | | | | | | | | | | |v | | 3/15********************************************************* 2863 +1 day | | | | | | v | | | 4/1 ****************************************************** 2710 0 days | | | | | | v | | | 4/15**************************************************** 2620 +2 days | | | | | | v | | | 5/1 ************************************************ 2421 +1 day | | | | | | | | | | Pin Sus 1st 1" Pk. Bloom Cut-Out Terminate | | head Sq. Flowr Boll +---+---+ +---+---+ +---+---+ | | S M F S M F S M F | +-------+-------+-------+-------+-------+-------+-------+-------+-------+-+ 0 400 800 1200 1600 2000 2400 2800 3200 3600 HEAT UNITS ACCUMULATED FROM PLANTING to AUG 23 v = Heat Units on AUG 16; S,M,F = Short, Medium, and Full Season Varieties INSECT UPDATE -------------------------------- Cotton can sustain heavy leaf loss without declines in yield (up to 25%). Control late season defoliator pests only if they threaten an efficient & timely defoliation. IGRs may be used for whitefly control up to Sept. 30. The IGR threshold is 3-5 adults/leaf AND 1 large nymph/disk or when 39-57% leaves have 3 or more WF adults (12-17 leaves out of 30) AND 40% leaf disks (quarter- size) have 1 or more large visible nymphs (12 out of 30 disks). The WF threshold for non-IGR sprays is 5 adults/leaf. Beneficials can help delay WF populations. Sweep for Lygus; treat if there are 15-20 total Lygus/100 sweeps (higher levels may be used as cotton approaches cut-out). Check for nymphs & survey for damaged squares (25%) before treating (pce 8/24). AUG 24 - AUG 30 WEATHER -------------------------------- WEEK HIGH LOW HEAT UNITS 30 yr Norm.: 98 65 161 Last Year : 97 68 169 WEATHER UPDATE, STATISTICS & ESTIMATED COTTON WATER USE -------------------------------------------------------------- Mostly sunny, hot and humid this week with a chance for thunderstorms each day. Temperatures should average about 3 degrees above normal. The probability of rain is highest in the southeast and central production areas. This week's forecast for temperatures and humidity should generate heat stress conditions across much of central and western Arizona. Heat Units (HU) are running about 1 day ahead of normal. HU last week = 166. Heat Unit accumulation since Jan 1 = 3110; Last year = 3464; 30 year normal = 3107. Planting date : 3/15 4/1 4/15 5/1 Water Use (last week): 1.98" 1.98" 1.98" 1.98" AGRONOMY UPDATE -------------------------------- As we go through the later days of August we are also rapidly approaching the days where the probabilities of taking a flower all the way to a mature, har- vestable boll are diminishing. Therefore, fields need to be monitored regular- ly with respect to the development of the boll load, crop vigor, and progres- sion toward cut-out. Counting the number of nodes above the top (first posi- tion) white flower (NAWF) is an easy measure to estimate stage of growth. When the NAWF count in a field is 5 or less the field is rapidly progressing toward cut-out and the last bolls for harvest can be identified. Whenever the last bolls intended for harvest have been identified by the manager, those bolls require 600 HU to develop from a flower to a full sized, hard boll. (JCS 8/23) SAFFORD COTTON DEVELOPMENT ADVISORY AUG 31, 1997 PLANTING +/- normal DATE+-------------------------------------------------------------------------+ | | | | | | | | | | | | | | | | v | | 3/15************************************************************* 3029 +1 day | | | | | | |v | | 4/1 ********************************************************** 2876 0 days | | | | | | v| | | 4/15******************************************************** 2786 +2 days | | | | | | v | | | 5/1 **************************************************** 2587 +1 day | | | | | | | | | | Pin Sus 1st 1" Pk. Bloom Cut-Out Terminate | | head Sq. Flowr Boll +---+---+ +---+---+ +---+---+ | | S M F S M F S M F | +-------+-------+-------+-------+-------+-------+-------+-------+-------+-+ 0 400 800 1200 1600 2000 2400 2800 3200 3600 HEAT UNITS ACCUMULATED FROM PLANTING to AUG 30 v = Heat Units on AUG 23; S,M,F = Short, Medium, and Full Season Varieties INSECT UPDATE -------------------------------- Cotton can sustain heavy leaf loss without declines in yield (up to 25%). Control late season defoliator pests only if they threaten an efficient & timely defoliation. IGRs may be used for whitefly control up to Sept. 30. The IGR threshold is 3-5 adults/leaf AND 1 large nymph/disk or when 39-57% leaves have 3 or more WF adults (12-17 leaves out of 30) AND 40% leaf disks (quarter- size) have 1 or more large visible nymphs (12 out of 30 disks). The WF threshold for non-IGR sprays is 5 adults/leaf. Beneficials can help delay WF populations. Sweep for Lygus; treat if there are 15-20 total Lygus/100 sweeps (higher levels may be used as cotton approaches cut-out). Check for nymphs & survey for damaged squares (25%) before treating (pce 8/24). AUG 31 - SEP 6 WEATHER -------------------------------- WEEK HIGH LOW HEAT UNITS 30 yr Norm.: 96 63 154 Last Year : 91 64 156 WEATHER UPDATE, STATISTICS & ESTIMATED COTTON WATER USE -------------------------------------------------------------- Mostly sunny and humid with near normal temperatures this week. Thunderstorms are possible each day, especially in western Arizona and the central mountains. El Nino has again developed in the tropical portions of the Pacific Ocean. El Nino is the name given to an abnormal warming of sea surface temperatures in the eastern Pacific near the equator. Pacific storm systems tend to come ashore farther south (e.g. Los Angeles or San Diego as compared with San Francisco) during El Nino events, increasing the chances for above normal fall and winter precipitation (October through March) in Arizona. Heat Units (HU) are running about 1 day ahead of normal. HU last week = 165. Heat Unit accumulation since Jan 1 = 3276; Last year = 3633; 30 year normal = 3268. Planting date : 3/15 4/1 4/15 5/1 Water Use (last week): 1.98" 1.98" 1.98" 1.98" AGRONOMY UPDATE -------------------------------- At the higher elevations of the state, this stage of the season causes us to consider the probabilities of taking blooms from this time forward to mature bolls that can be harvested in the fall. To go from a fresh bloom to a hard, full-sized green boll (stage at which fiber length development is complete), requires about 600 heat units (HU). The time required to accumulate 600 HU will begin to increase as daylengths continue to become shorter and tempera- tures begin to decline. For example, based on historical weather records, a 29 August bloom can be expected to be mature on 20 Sept. in Marana and on 26 Sept. in Safford. These same bolls could be open by 10 Oct. in Marana and 28 October in Safford. See a recent bulletin for more details. (JCS 8/30/97) SAFFORD COTTON DEVELOPMENT ADVISORY SEP 7, 1997 PLANTING +/- normal DATE+-------------------------------------------------------------------------+ | | | | | | | | | | | | | | | | v | | 3/15**************************************************************** 3193 +2 days | | | | | | | v | | 4/1 ************************************************************* 3040 0 days | | | | | | | v | | 4/15*********************************************************** 2950 +2 days | | | | | | v| | | 5/1 ******************************************************* 2751 +2 days | | | | | | | | | | Pin Sus 1st 1" Pk. Bloom Cut-Out Terminate | | head Sq. Flowr Boll +---+---+ +---+---+ +---+---+ | | S M F S M F S M F | +-------+-------+-------+-------+-------+-------+-------+-------+-------+-+ 0 400 800 1200 1600 2000 2400 2800 3200 3600 HEAT UNITS ACCUMULATED FROM PLANTING to SEP 6 v = Heat Units on AUG 30; S,M,F = Short, Medium, and Full Season Varieties INSECT UPDATE -------------------------------- As we approach mid-September, the majority of PBWs produced will diapause. This resting stage allows larvae to overwinter in small bolls, seeds or soil. Prevent production of late season, small bolls that are ideal for hosting PBW. Early plowdown (deep disking & other practices that disrupt the soil) can effectively reduce risk of PBW populations next season. These practices are also important as a means of limiting selection pressure for resistance to Bt cotton. Use harvest aids that reduce regrowth which can host large numbers of WFs through the fall. WF IGRs may be used up to 9/30/97; however, because their effects are slow-acting, IGRs should be applied early enough to impact numbers before the last generation of the season (pce 9/2). SEP 7 - SEP 13 WEATHER -------------------------------- WEEK HIGH LOW HEAT UNITS 30 yr Norm.: 95 62 147 Last Year : 90 63 139 WEATHER UPDATE, STATISTICS & ESTIMATED COTTON WATER USE -------------------------------------------------------------- Mostly sunny & humid with above normal temperatures this week. Chance for scattered thunderstorms each day. Temperatures are forecast to run about 5 degrees above normal. El Nino has developed in the tropical Pacific Ocean this summer. The meteor- ological variable in Arizona most impacted by El Nino is winter precipitation. Above normal winter (October - March) precipitation is a common occurrence in El Nino years. Some past El Nino events have produced floods; however, flooding is by no means a sure thing with El Nino. El Nino does raise the probability of having precipitation amounts that can produce floods. Heat Units (HU) are running about 1 day ahead of normal. HU last week = 165. Heat Unit accumulation since Jan 1 = 3440; Last year = 3789; 30 year normal = 3423. Planting date : 3/15 4/1 4/15 5/1 Water Use (last week): 1.87" 1.98" 1.98" 1.98" AGRONOMY UPDATE -------------------------------- As the final management steps are taken with the 1997 cotton crop and fields are defoliated, it is important to recognize a number of factors that serve to impact defoliation efforts. The chemical defoliant is always a common point of focus. However, factors such as: 1) plant-water status and 2) N fertility sta- tus at the time of defoliation; 3) weather conditions; and 4) the conditions of the leaves also serve to impact the effectiveness of a defoliant applica- tion. Therefore, it is important to take all of these factors into considera- when making a defoliant application or evaluating the results from one. We have a number of bulletins addressing these points in more detail. If you need more information, please contact the local UA extension office. (JCS 9/06/97)