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University of Arizona
March 2nd 2014 Vegetable IPM Updates
Insect Management
Weed Science
Upcoming Events
Some Videos to Check Out
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 2014 Lettuce Insect, Disease and Weed Losses Workshop next Thursday, April 24 at the Yuma Agricultural Center beginning at noon (a yummy lunch is provided at no cost). The information provided by PCAs and growers during these workshops can be very useful to the lettuce 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 grant proposals. 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: 2004-2013 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 2014 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:



Powdery Mildew

Spring is a time of transition for agriculture in the desert southwest. Cool season crop harvest is wrapping up and spring and summer crops are being planted and grown. This is also powdery mildew season. Powdery mildew can develop on commercial crops, such as late-season lettuce, wheat or melons, as well as landscape plants. It is not too early to begin considering management options for powdery mildew on melons. The disease generally is favored by dry weather conditions, moderate temperatures, reduced light intensity, fertile soil, and succulent plant growth. The overall risk of powdery mildew increases as more of these factors become established in a melon field. Dry weather conditions and fertile soil are givens in our desert melon production fields. Spores of the melon powdery mildew pathogen, Podosphaera xanthii, can germinate to initiate disease at temperatures ranging from 72 to 88°F, and optimally at about 82°F. These moderate temperatures as well as reduced light intensity and succulent plant growth all become increasingly prevalent as the melon plantings grow rapidly during April and May. Another factor to consider when determining powdery mildew risk is the inherent susceptibility of the melon cultivar being grown. Those varieties known to be susceptible to powdery mildew will require implementation of a rigorous disease management program involving applications of fungicides with differing modes of action throughout the period of high disease risk. On the other hand, melon varieties that have moderate to high levels of genetic resistance to the pathogen will require less fungicide inputs. To achieve maximum levels of disease control, powdery mildew fungicide application programs must be initiated before the visible detection of the fungus. Good levels of disease control can also be attained by waiting to begin fungicide applications until no later than the very first sign of disease in the field. These initial infection sites are often on the underside of leaves, so frequent and comprehensive examination of the melon planting is required.

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


Weed Science:

The University Of Arizona Herbarium

Most people are unaware that the largest herbarium in the southwest is located in the center of the university of Arizona campus. The University of Arizona Herbarium is located in the second oldest building on campus. It was established in 1850, the year before the University of Arizona opened its doors. Originally located in old Main, it contained 700 native plant specimens from southern and central Arizona. It now contains over 420,000 plant specimens and over 40,000 mycological specimens.

The Herbarium is a plant museum where specimens are dried, preserved and cataloged. It is used by scientists, students, public agencies and homeowners. It is used for many purposes, which include documenting rare and endangered species, evolution and morphology of species that have occurred in the region over the last 150 years. The specimens are sometimes used as a source of DNA for molecular analysis.

Herring Hall, where the herbarium is located, was originally built in 1903 as the man’s gymnasium. It was built with a $5000 gift from the Copper Queen mining company. This gift was arranged by William Herring who was the legal consul for the company.

Specimens can be submitted to the Herbarium and it is also open daily to the public. Please contact them first if you plan to submit samples.

Click picture to listen to Barry video link
To contact Barry Tickes go to:


Check Out These Videos!
Upcoming Events:



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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