The latest Arizona Vegetable Integrated Pest Management Update from the University of Arizona (UA) Cooperative Extension in Yuma, Ariz. released May 17, 2011.

2010-2011 insecticide usage in head lettuce

By John Palumbo, UA Research Scientist and Extension Specialist

Results from the recent Lettuce Insect Losses Workshop reveal some interesting trends in insecticide usage on desert head lettuce. Data was summarized from pest control advisers (PCAs) and grower surveys completed over the past seven years.

When compared by class of chemistry using the IRAC mode of action classification system, the pyrethroids, applied as foliar sprays and chemigations, have consistently been the most commonly used insecticide class by far. Over the past few years the usage has been declining, but only slightly.

The spinosyns (Radiant and Success) are the second most commonly used class of insecticides, where the usage increased this season compared.

In contrast, estimates of diamide usage (Coragen, Voliam Xpress, Vetica) showed that PCAs used almost 20 percent less of these products in 2010 and 2011.

Not surprising, Ketoenol usage (Movento) was up about 40 percent compared to 2010 and neonicotinoid usage remained about the same.

The usage of the broadly toxic, old chemistry (organophosphates /carbamate/endosulfan) on head lettuce acreage continued to decline in 2010 and 2011; relative to the newer, selective reduced-risk products which overall increased considerably this season.

The most commonly used insecticides in fall and spring lettuce also correspond to the key pests that typically occur throughout the season.

To view a summary of the insecticide usage by chemical class over the past seven seasons, as well as the 15 most commonly used insecticides on head lettuce in 2010-2011, click on this link - Insecticide Use AZ Head Lettuce 2005-11.

Contact Palumbo: (928) 928-782-3836 or jpalumbo@ag.arizona.edu.