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

Managing Insect Pests During Stand Establishment

It’s that time of the year again. Desert growers have begun planting fall melons, transplanting cabbage and will be direct seeding produce crops in just a few weeks. Accordingly, PCAs and growers will be faced with a number of important insect management issues. As crops begin to emerge, you can expect to encounter a number of insect species that have the potential to cause serious economic losses to crop stands. These include flea beetles, crickets (sometimes grass hoppers), darkling and rove beetles, and saltmarsh caterpillars (‘woolly worms’). These insects all have chewing mouthparts and most are capable of consuming large amounts of leaf tissue in a short period of time. Seedling crops at the cotyledon stage are most susceptible, and feeding by these pests can devour much of the cotyledons or outright kill small plants. If left unprotected, larger seedling plants (1-2 leaf stage) can sustain significant feeding damage on the terminal growing points or newly emerged leaves. Not only can this feeding stunt plant growth, but can result in lack of stand uniformity and maturity at harvest. Host sources of flea beetle, cricket and "woolly worm" infestations include numerous summer crops (e.g., sudan grass, cotton and alfalfa) and weeds (e.g., purslane). Recently, we’ve observed high numbers of flea beetles and crickets at the Yuma Agricultural Center, and received reports of saltmarsh caterpillars on pima cotton. Experience indicates that melon fields planted adjacent to these crops/weedy areas are at a high risk from these seedling pests, particularly flea beetles. As summer crops are harvested or terminated during the next several weeks, these seedling pests typically move to the next available host crop; lettuce, cole crops and melons. Fortunately, there are many registered insecticide alternatives available that can be applied via sprinkler chemigation (i.e., pyreethroids) or foliar sprays (i.e., methomyl, neonicotinoids) that can cost-effectively minimize their abundance and damage to emerging produce and melon crops. Additionally, seed treatments are available for lettuce and cole crops that will protect stands from flea beetles. For more information on insect pests of leafy vegetables and melons at stand establishment please see:Insect Management on Desert Produce and Melons: Pests at Stand Establishment.

Pale-striped flea beetle

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

Click picture to listen to John’s update video link

To contact John Palumbo go to:



Plant Pathogen Survival in the Desert

As the seemingly unending days of summer heat in the desert persist, we can seek refuge in air-conditioned vehicles or buildings and can obtain food from any number of sources at any time. Not so for plant pathogens, which must survive high temperatures and lack of food by employing other tactics. A few plant pathogens can thrive at temperatures common in the desert during the summer and cause disease on plants growing at that time; however, most others cannot function at temperatures much above 90°F. To survive inhospitable temperatures or lack of a host on which to feed, fungal pathogens often produce thick-walled durable spores or other structures that will allow the organisms to survive hostile environments in a dormant state. The visible dark-colored sclerotia produced by the lettuce Sclerotinia pathogens are examples of such structures. Much smaller sclerotia and thick-walled spores facilitate long-term survival of the soil-borne pathogens Rhizoctonia and Fusarium, respectively. On the other hand, bacterial plant pathogens do not have recognized survival structures, but can subsist for some time in a reduced metabolic state on, in, or near living or dead plant tissue. Virus pathogens also cannot make resistant structures, so survival usually occurs in vectors or living plants. These plants can include weeds or cultivated crops that do not express disease symptoms, but serve as sources of virus to visiting insect vectors. Finally, nematode survival stages can include eggs and certain larval forms. Many of the cultural disease management methods that we employ are effective because they disrupt the normal survival capacity of these plant pathogens.

Sclerotinia sclerotiorum

Click picture to listen to Mike's update video link

To contact Mike Matheron go to:


Weed Science:

Herbicide Registrations for Different Types of Lettuce

Herbicide registrations were always the same for all types of lettuce until 2009 when this changed. Prior to around 1920 there was very little lettuce produced in this part of the country and what was produced was mostly leaf or butter types. After 1920 this changed dramatically. Lettuce acreage became increasingly important in the west after 1920 when the acreage increased and the type of lettuce produced changed from leaf to iceberg. The shift to iceberg was largely because iceberg shipped long distances better than other types. In the early years, lettuce was packed in sheds, placed in crates and cooled with ice. More than 80% of the lettuce produced in this region was iceberg when the first herbicides were registered for use on it. The data collected to support herbicide registrations were done largely with iceberg lettuce and only “lettuce” appeared on the labels. Vacuum cooling was adopted in the 1950’s and the types of lettuce produced here have shifted over the last 20 years. Now almost 50% of the acreage is leaf types (including romaine). The most broad-spectrum of the limited herbicides registered for use on lettuce is Pronamide (Kerb). When EPA reassessed the registration of Pronamide in lettuce in 2009 they noted that data had been collected only for iceberg types and cancelled the registration for leaf lettuce. Dow Agrichemicals have been working to collect the needed data for leaf lettuce and expects the reregistration in November of this year.

Click picture to listen to Barry'update video
To contact Barry Tickes go to:


Question to the IPM Team:
One of our student subscribers brought this bug to the IPM team. It’s a male carpenter bee possibly Xilocopa Varipuncta. Females are black, males are fuzzy gold. Only the females have stingers and will only sting when provoked. Their named carpenter bees comes after their ability to burrow into hard wood or telephone poles to make their nests.
Your feedback is always welcomed!
Wikipaedia: December 8, 2014


Upcoming Events:
21st Annual Maricopa County Short Course, August 27, 2015

The 21st Annual Maricopa County Short Course Thursday, August 27, 2015 12:30 to 5:00 PM University of Arizona Maricopa County Cooperative Extension 4341 East Broadway Road Phoenix, AZ 85040. 5 hours CEU’s granted for AZ Dept of Ag and OPM

Utility of New Insecticide Modes of Action in Crops and Turf & Ornamentals: Preserving Them for the Long Term

Recent introductions of new insecticides and their modes of action John Palumbo, UA Professor/Extension Specialist, Vegetable Crops, Department of Entomology, Yuma Agricultural Center

Strategic use of new insecticides in vegetable crops John Palumbo

Strategic use of new insecticides in cotton Peter Ellsworth, UA Full Specialist/Professor, IPM Coordinator & Director, Arizona Pest Management Center, Department of Entomology, Maricopa Agricultural Center

Strategic use of new insecticides in alfalfa and forage crops Ayman Mostafa, UA IPM Area Extension Agent, Field Crops

Maricopa County Strategic use of new insecticides in turf and ornamentals Kai Umeda, UA Turfgrass Extension Agent, Maricopa County

Strategies to integrate new insecticides across the landscapes of AZ to avert resistance development and ensure pollinator safety Panel summary

Preseason Vegetable Workshop, Sept. 2, 2015
The 2015 Preseason Vegetable Workshop for the winter vegetable industry will be held Sept. 2 in Yuma, Ariz. at the Yuma Agricultural Center located on 6425 W. 8th. St. Yuma, AZ 85364. Application submitted for 2.5 CCA, PCA CA and AZ CEU’s
7:30 - Registration
8:00 - Comparing, improving seed spacing uniformity of vacuum and belt planters - Mark Siemens, YAC;
8:30 - Update on the Yuma Center of Excellence for Desert Agriculture - Paul Brierley, UA College of Agriculture & Life Sciences;
8:45 - Year 3 of web-based mapping for Yuma vegetable seed production isolations - Kurt Nolte, Yuma County Cooperative Extension
9:00 - Update on the registration of Kerb on leaf lettuce weed management - Barry Tickes, UA Extension, Yuma, La Paz, and Mohave counties
9:30 - Brief announcements from industry
9:35 - Break
9:50 - Insect management tips for fall produce and melons - John Palumbo, YAC
10:30 - Downy mildew on vegetable crops - Winning the battle - Mike Matheron, YAC
11:00 - Biocontrol of lettuce drop revisited - Barry Pryor, UA
11:30 - Update on the strengthening El Niño: Potential pest, pesticide management impacts for the produce season - Paul Brown, UA
12:00 - Lunch, courtesy of Yuma County Cooperative Extension

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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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