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March 2nd 2014 Vegetable IPM Updates
Insect Management
Weed Science
Upcoming Events
Pheromone/Sticky Trap Monitoring Network
Insect Management:

Lettuce Insect Losses and Insecticide Usage

Since 2004, the UA Vegetable IPM Team has annually surveyed PCAs and growers to document insect pest activity and pesticide usage in Arizona lettuce through interactive workshops. We will be holding the 2015 Lettuce Insect, Disease and Weed Losses Workshop next Wednesday, April 8 at the Yuma Agricultural Center beginning at noon (lunch is provided at no cost). The information provided by PCAs and growers during these workshops can be very useful to the local produce industry. First, the data can be extremely helpful in addressing state and federal regulatory issues by providing “real world" information on insect pest status and insecticides usage.
In the past data generated from the surveys has been used to support registrations of key insecticide products (i.e., Lannate). Secondly, from an academic perspective, the results of these surveys provide us with a historic record of insect occurrences which allows us to prioritize some of our research and educational activities. Over the years, insecticide usage data has provided valuable support for many of the grant programs we request funding from. Finally, and perhaps most importantly for PCAs, it can translate their efforts into economic terms for their growers, and confirms their value to the lettuce industry by showing the importance of key insect pests and their cost-effective management in desert lettuce production. For example, survey results from the Lettuce Insect Losses and Insecticide Use Summary: 2004-2014 shows that on average, 1) costs associated with pest management fees have increased steadily where the cost of scouting and making management decisions by PCAs are well over $20/acre, 2) Leps, aphids and thrips are the most important economic pests in fall and spring lettuce, and 3) the use of older, broadly toxic insecticides (OP/Carbamates/Endosulfan) has dropped significantly, whereas use of the newer, softer reduced-risk chemistries (e.g., Radiant, imidacloprid, and diamides) continues to increase. Of course, PCAs already know this, but these surveys document this information for those less involved with the day-to-day activities of IPM in desert lettuce. Hopefully PCAs and growers see the value in this process and will join us next week at 2015 Lettuce Insect, Disease and Weed Losses Workshop. See you there!
Remember, When in Doubt . . . . . “SCOUT”

Click picture to listen to John’s update video link

To contact John Palumbo go to:



Comparative Efficacy of Downy Mildew Fungicides on Spinach

A downy mildew fungicide efficacy trial was conducted in conjunction with the International Spinach Conference held in Yuma during the last week of February. Eighteen different fungicides were evaluated, including biofungicide/organic products as well as conventional chemistries. Plots were planted with the cultivar Viroflay, which is susceptible to all known races of the downy mildew pathogen. Three applications of each fungicide were applied (Feb 6, 16, and 23). Disease severity was assessed by counting the number of leaves within two 1-square-foot areas within each plot. In plots sprayed only with water, 62% of spinach leaves were infected. Five conventional chemistries held spinach downy mildew to levels ranging from less than 0.5% to no downy mildew present. These products included Aliette, Revus, Blockade (also known as Actigard), Zampro, and Ranman. On the other hand, for the 10 biofungicides tested, disease severity ranged from 38 to 58% infected spinach leaves. Since the tolerance level for downy mildew on baby-leaf spinach is very low, none of the tested biological/organic products were effective on their own. The results of this fungicide trial provide good news for conventional spinach growers but are disappointing for organic spinach producers.

Click picture to listen to Mike's update video link
To contact Mike Matheron go to:


Weed Science:


Dodder has been a difficult to control weed in this area for as long as crops have been grown. It was kept in check for many years but seems to have been getting worse in recent years. It is listed as one of the 10 most problematic weeds in the U.S. by the Department of Agriculture. There are more than 150 species of dodder. Fifteen of these can be found in Arizona, 3 are common and one, field dodder (Cuscuta campestris), is an economic problem in the lower Colorado River region. It can be a problem on many crops grown during the summer months including melons, safflower, asparagus, sugar beets, beans, alfalfa and others. Dodder is an unusual weed. It is a parasitic annual that has no leaves or roots after it is attached to a host. It obtains all of its energy from the plants it attaches to. Dodder germinates near the soil surface and lives off of food reserves in the seed. It must attach to a host within 5 to 10 days or it will die. After it has found a suitable host, it produces adventitious roots called haustoria that grow into the vascular system of the host plant. After it is attached, the lower portion of the dodder seedling dies and all contact with the soil ends. Dodder seed is small, about 1/16 inch in diameter, and germinates in the spring or summer once the soil temperature reaches about 60 degrees. It is very prolific and each plant produces several thousand seeds. The seed is hard and less than a third can germinate in the first season. The remainder can remain dormant but viable for 20 years or more. The seed is small and light enough to float in water and blow in the wind. Most of the movement is probably from contaminated crops, seed and equipment. Controlling this weed starts by reducing seed movement into an area. Most states and countries have laws that prohibit the import of dodder seed. A major cause for the spread of dodder in Arizona has probably been in seed. Once it is present in a field, annual crops that are poor hosts can reduce the spread of this weed. Poor host crops include grasses, grains, and other monocots. Other weeds can serve as hosts and should be eliminated. Preemergent herbicides can be effective in keeping this weed from becoming established. Postemergence herbicides need to at least temporarily destroy the host. Perennial crops, like alfalfa, can be temporarily burned to the ground with contact herbicides like Gramoxone, Chateau or Scythe plus an adjuvant. Dodder can be selectively killed with glyphosate in Roundup Ready Alfalfa. The most effective control is with preemergent herbicides. These include trifluralin, pendimethalin, benefin, Dacthal and others. When the level of these herbicides has dropped to sub-lethal amounts, dodder seed will germinate and survive. Repeated applications are normally required
Click picture to listen to Barry video link
To contact Barry Tickes go to:

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 Thanks !

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

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Area wide Insect Trapping Network

Apr 1, 2015

Results of pheromone and sticky trap catches can be viewed here.

Corn earworm: Corn earworm moth activity was very high in some locations over the past 2 weeks, particularly in those areas near alfalfa.

Beet armyworm: BAW activity was very high during March consistent with warm temperatures.

Cabbage looper: Similarly, cabbage looper moth flights during March were nearly as high as observed in October and November.

Whitefly: Adult movement remains very low similar to what we observed last year.

Thrips: Thrips movement picked up in March consistent with the reduction in lettuce acres throughout the region.

Leafminers: Numbers on traps remain low across all trap locations.

Aphids: Alate (winged) activity was low over the past two weeks, with a slight peak last week. Overall, aphid flight were considerably lower than what we recorded spring in 2014.

To contact John Palumbo go to:



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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