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March 2nd 2014 Vegetable IPM Updates
Insect Management
Weed Science
Insect Management:

Areawide Diamondback Moth Trapping Network Established in Yuma

In response to the recent outbreaks of Diamondback moth (DBM) , Plutella xylostella in Yuma, we have established a pheromone trap network designed to monitor the activity and movement of adult populations of DBM. PCAs have had difficulty controlling DBM in cabbage, broccoli and cauliflower since October. Wing Traps with DBM pheromone lures have been placed in Roll, Wellton, Dome Valley, Gila Valley and Yuma Valley in locations where Cole crops are presently being grown, or in areas where infestations were known to occur this fall. The data we collect is not intended to indicate field infestations, as trap data is largely a reflection of adult movement. The data may reflect emergence/ activity of adults in adjacent fields with known infestations, or provide an indication that DBM may be moving into fields not previously infested. If nothing else, the data may make PCAs aware of increased pest activity in some areas and encourage intensified scouting in susceptible produce fields. DBM are still active in many fields, and most recently we’ve observed that populations are beginning to spread into direct-seeded crops that were not previously effected by DBM. For this reason, we are tracking moth activity to monitor their activity relative weather conditions and crops sources. We have a historical perspective of DBM activity in Yuma. From 1998-2000, we established a pheromone trap network during the winter and spring in Yuma which included DBM. Not surprisingly during that 2-year trapping period DBM counts never exceed 6 moths/trap/day at any time during the spring season. DBM have historically been a secondary pest, that may cause issues in spring cabbage crops. However, in just the few weeks we’ve been trapping DBM since Dec 20, we’ve had four trap locations where DBM counts have exceeded 10 moths/trap/day and in one location (Co. 9th and Ave F) over 25 moths /day were recorded. These traps were all located in the Yuma Valley, stretching from Co. 21st up to Co. 9th street. We will continue to monitor DBM trap activity throughout the season, as well as trap population activity throughout the summer to determine whether DBM is active when brassica crops are not available. This may give us an indication of the potential for more problems going into next season. From a historical perspective, trap counts during the summer of 1999 in the Yuma Valley occasionally caught DBM moths in traps at low levels (0.2-1.2 moths/trap/night from July-August). We concluded at that time that many of the DBM captured may have come in with transplants, as we were uncertain whether DBM was capable of over summering in the desert in the absence of brassica crops. We hope to gain more insight into the pest’s activity during summer months in Yuma this year by actively trapping throughout the area. For access to DBM trap counts please visit Areawide Diamondback Moth Trapping Network.


Diamondback in Yuma, AZ VIPM_Update_Vol_8_Num_1_002.jpg

Remember, When in Doubt . . . . . “SCOUT”

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Wet Weather Raises Threat of Downy Mildew

The moist weather pattern recently affecting Arizona in general and Yuma County in particular is providing environmental conditions favorable for downy mildew development on crops susceptible to this disease. Rainfall in vegetable production regions of Yuma County from Dec 21 to Jan 1 have ranged from 0.8 to 1.5 inches. These periods of rainfall plus the associated high relative humidity and extended periods of leaf wetness provide ideal conditions for rapid development of downy mildew. Disease severity is a function of the daily duration of plant wetness, with increasing number of nights and following mornings with wet plants resulting in increasing disease. If not already initiated, now is the time to start a preventative fungicide application program for downy mildew on susceptible crops. Waiting until the symptoms of downy mildew are visible before beginning fungicide applications can result in a less than satisfactory level of disease management. By the time downy mildew lesions are observed, many more are likely present but have not developed to a sufficient extent to be visible. Fungicide evaluation trials conducted at the Yuma Agricultural Center as well as in other states have demonstrated statistically significant reduction in disease by application of fungicides such as Actigard, Aliette, Cabrio, Curzate, Forum, Manzate, Orondis, Presidio, Previcur Flex, Prophyt, Ranman, Reason, Revus, and Tanos. Several different modes of action are represented by these compounds, thus facilitating alternation among different chemistries for effective disease management as well as pathogen resistance management. Periods of low relative humidity and little or no dew on leaves will help arrest downy mildew development. However, constant vigilance is needed, as future occurrences.

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Weed Science:

Late Season Applications of Prowl H2O on Broccoli and Cauliflower Grown for Seed

Broccoli and cauliflower seed crops are typically extended into the early summer and can get ugly with summer annual and perennial weeds by harvest time. Some of these weeds have seeds that are the same size and density as cole crop seeds and they can only be removed by costly hand labor. Legumes such as yellow and white sweet clover and volunteer alfalfa can be particularly difficult to remove.
Prowl H2O can be applied from now into February to help keep many of these weeds in check. The rate allowed goes from 1.0 to 2.1 pts. but this is likely not enough. It is safe and more effective at twice this rate. The soil residual activity from higher rates will be twice as long, however, and this may pose an added threat to rotational crops. The label restrictions are from 4 to 12 months for most crops. Although water run applications in the furrows works well, chemigation is not allowed on the label. Applications should be made as a directed spray without getting the product on the foliage. Very high rates over the top of the crop can stunt both broccoli and cauliflower.

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Areawide Insect Trapping Network:

December 7, 2016

Our area-wide trapping network is up and running. The project is designed to measure the activity and movement of adult populations of a number of key pests. The project is being funded by the Arizona Iceberg Lettuce Research Council, and will hopefully provide an indication of when pest activity (e.g., corn earworm moth flights) is increasing based on pheromone/sticky trap captures. The data is not intended to indicate field infestations, as trap data is largely a reflection of adult movement. If nothing else, the data may make PCAs aware of increased pest activity in some areas and encourage intensified scouting in susceptible produce fields. The pests being monitored include: corn earworm, tobacco budworm, beet armyworm, cabbage looper using pheromone traps; aphids, thrips and whiteflies using yellow sticky traps. A total of 15 trapping locations have been established. Traps will be checked weekly and data will be made available in the bi-weekly Vegetable IPM updates. If a PCA or grower is interested in weekly counts, those can be made available by contacting us.
Results of pheromone and sticky trap catches can be viewed here.

Corn earworm: Moth activity remains at seasonal low levels in all trap locations.

Beet armyworm: Armyworm moths remain at low levels during early January. Should remain low until warmer nighttime temperatures pick up in the spring.

Cabbage looper: Similarly, cabbage looper moth activity remain low.

Whitefly: Adult movement is still being measured in some locations, but was at seasonal lows last week.

Thrips: Thrips movement is continuing to subside in all locations, likely a result rain over the past few weeks.

Aphids: Aphid flights picked up again on some traps in late December in the Yuma Valley. We also actively picking up green peach aphids in those traps.

Leafminers: Adult movement is at seasonal lows in all trap locations.
** Starting next week we will setting Diamondback Moth Pheromone Traps in several areas.
To contact John Palumbo go to:

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The Vegetable IPM Updates Archive page provides links to updates from previous weeks.

The Vegetable IPM Video Archive page contains a collection of educational videos from current research work in vegetable crops by University of Arizona Researchers.


For questions or comments on any of the topics please contact Marco Pena at the Yuma Agricultural Center.
College of Agriculture, The University of Arizona, Tucson, AZ.

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