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University of Arizona
March 2nd 2014 Vegetable IPM Updates
Insect Management
Weed Science
Pheromone/Sticky Trap Monitoring Network
Insect Management:

Insecticide Modes of Action on Desert Produce and Melons

As the produce season winds down and the melon season begins to pick up, it is an important time to review the insecticide chemistries that you may have used this winter/spring on produce crops and those that you may consider using on spring melons. Sustaining insecticide efficacy that annually provides cost-effective crop protection requires a conscious effort on the part of PCAs and growers to prevent insecticide resistance. Over the past 20 years, the Agrochemical Industry has developed and brought to the market
an unprecedented number of new chemistries that are highly effective, selective and more safe than their chemical predecessors. These include the neonicotinoids, spinosyns, tetramic acid derivatives and diamides to name a few. Most recently, a few new chemistries have been added including the sulfoxamines (Sequoia, Transform), a butenolide (Sivanto) and a mitochondrial complex I electron transport inhibitor (Torac). The development of new chemistries has slowed a bit and older chemistries are continually being phased out of the marketplace. Thus, it is imperative to sustain the efficacy of the newer IPM tools currently available. Insecticide resistance management (IRM) is now more important than ever. The most fundamental approach to IRM is to minimize the selection of resistance to any one type of insecticide. Historically, alternating or rotating compounds with different modes of action (MOA) has provided sustainable and effective IRM in our desert cropping systems. The Insecticide Resistance Action Committee (IRAC), a coordinated crop protection industry group, was formed to develop guidelines to delay or prevent resistance. Using their most recent IRAC MOA Classification Brochure we have produced a table which provides Insecticide Modes of Action on Desert Produce and Melon Crops. We also provide general information on the route of activity and pest spectrum for each chemistry. These classification lists will provide you with an additional set of guidelines for the selection of insecticides that can be used in desert IPM programs.

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

Click picture to listen to John’s update video link

To contact John Palumbo go to: jpalumbo@ag.arizona.edu



The Year of Downy Mildew

The 2014-2015 vegetable production season in Yuma County, Arizona is approaching the finish line, and probably not fast enough for pest control advisors striving to manage downy mildew. The disease has been a tenacious foe this season, even in areas that did not receive appreciable rainfall and normally do not have high downy mildew pressure. The pathogens that cause downy mildew on lettuce, spinach, onions and other crops form spores at night when the relative humidity in the leaf canopy is near or at 100%. Water supplied to crops by furrow irrigation and especially to crops irrigated with sprinkler irrigation is sufficient to create high humidity conditions and facilitate dew formation in the crop canopy. Calm evenings with little or no wind also favor spore production by allowing humid air to remain in the leaf canopy. Four AZMET weather stations are located within the vegetable production region in Yuma County. The maximum relative humidity (RH) measured every evening can be a useful predictor of downy mildew development and severity. A look at the number of nights where the maximum RH was at or above 90% can help estimate the number of potential dew formation nights in the different regions where these weather stations are located. For example, from Nov 2014 to Feb 2015, the average number of nights with RH at or above 90% at the Yuma Valley, North Gila Valley, Roll, and Yuma South AZMET stations was 8, 16, 16, and 19, respectively. For the same time period during the 2013-2014 production season, the average number of nights with RH at or above 90% at the same weather stations was 4, 12, 14, and 14, respectively. The increased incidence and severity of downy mildew observed on lettuce and other crops at the Yuma Agricultural Center this season compared to last season correlates well with the RH levels recorded at the nearby Yuma Valley AZMET weather station during each season. Several other factors, especially a crop’s genetic tolerance or resistance to downy mildew, can impact the final severity of the disease in any given vegetable planting. However, as the number of hours of leaf wetness in the evening and early morning hours increases, the potential for downy mildew development and increased disease severity rises as well.

Click picture to listen to Mike's update video link
To contact Mike Matheron go to: matheron@ag.arizona.edu.


Weed Science:

Weeds Can Reroot

Few farmers can walk through their fields without stopping to pull an occasional weed that is growing above the crop. Uprooting weeds mechanically or by hand can be very satisfying when there are few of them. Pulling or cultivating weeds does not always mean that they will die and not produce seed. Cheryl Wilen, a farm advisor in San Diego County, has posted the following video of of an annual sowthistle plant that was uprooted but continued to flower and produce seed. ( Click here to watch Chetyl’s Video) studied the influence of uprooting time on seed production in common purslane. The objective of his study was to determine the viability of purslane seed produced from plant that were uprooted from one to six weeks after emergence. He found that no viable seed was produced from plants that were uprooted one and two weeks after emergence. Some viable seed was produced at three weeks and this increased rapidly at 4 to 6 weeks. Preirrigating during ground preparation and not disking emerged purslane for three weeks or more increases rather than decreases the problem during the growing season.
Click picture to listen to Barry video link
To contact Barry Tickes go to: btickes@ag.arizona.edu.

Upcoming Events:


Lettuce Insect, Disease, and Weed Losses Workshop

April 8, 2015 (RSVP requested)
12:00-3:00 pm (Lunch Provided)
Yuma Agricultural Center
6425 W. 8th St., Yuma AZ 85364

3 Arizona PCA CEUs approved
2 California PCA CEUs approved
2 CCA CEUs approved

12:00 12:00 - 12:15  Welcome and Lunch
12:15 - 12:45  Explanation of the Lettuce Insect Losses Survey
12:45 - 1:30  Individual Completion of Questionnaires*
1:30 - 2:00  10 year Trends: Results from 2004-2014 Workshop/Surveys
2:00 - 2:30  Bagrada bug Update
2:30 - 3:00  New Insecticide Chemistry Update

* Questionnaires to be completed anonymously by PCA’s to ensure confidentiality.

Please let us know if you are planning on attending the workshop by either faxing this announcement back to us at 928-782-1940, calling 928-782-3836 or email us at:AZVegIPM-Team@email.arizona.edu Thanks !

If you have any questions in regard to the workshop please call Marco Pena at (928) 782-5871.


Alfalfa Pest Management Meeting
Tuesday March 31
9am to 12 (3 AZ and CA PCA CEUs applied for)
Arizona Western College
Parker, Az.

Alfalfa Leafhopper Update
John Palumbo, U of A Yuma Agriculture Center
9:30- 10:00
Environmental Conditions and Pest Management
Paul Brown, Dept. of Soil, Water & Environmental Science, U of A
Alfalfa Variety Pest Resistances and Dormancy Classes
Mike Ottman, Plant Science Dept. U of A
Resistance Management
Peter Ellsworth, U of A Maricopa Agriculture Center
11:00 -11:30
Yuma Agriculture Center Pesticide Diagnostic Laboratory
Marco Pena & Juan Pena, U of A Yuma Agriculture Center
11:30- 12:00
Alfalfa Weed Management update
B. Tickes, U of A Cooperative Extension

Real IPM
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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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