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Vegetable IPM Updates Archive
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Key Pest Activity in Late Produce Crops (March 8, 2017)
Foxglove Aphids: In the past two weeks, foxglove aphid (FGA), has increased dramatically in our untreated control lettuce plots here at the Yuma Ag Center. We’ve also had reports from PCAs of difficulty in controlling FGA, which is more abundant than I’ve seen in the past 5-6 years. In my opinion, this is the reason more spray applications are necessary for FGA control this season. Green peach aphids are also still prevalent in high numbers in our cole crops, but are rapidly declining in lettuce. Because aphid species are inherently different in their susceptibility to insecticides, the proper choice of product is important for achieving adequate control. In my lettuce trials, Sequoia, Sivanto, and Beleaf have provided the most consistent knockdown and residual control of FGA. For more information on FGA and insecticide alternatives for the various aphid species please view our Aphid Control Chart-2017 and Foxglove Aphid on Desert Lettuce Crops

Thrips: In contrast, western flower thrips have been very light this spring, largely due to heavier than average rainfall and cooler weather for the past few weeks. However, as drier conditions prevail, PCAs should expect thrips numbers to steadily increase with the warmer weather. This is particularly important on late-lettuce where “bioconcentration" of thrips occurs each year as lettuce acreage declines. Each time a lettuce field is harvested and disked, adult thrips populations disperse from these areas into the next available lettuce field. As the number of lettuce acres becomes reduced near the end of the season, this creates a bottleneck effect that concentrates high numbers of thrips adults on the remaining fields under production. This can often make chemical control very difficult, particularly in March, as thrips adults may continually re-infest fields following spray applications. See the Thrips Control Chart 2017 for more information.

Diamondback Moth (DBM): Reports of DBM infestations are still coming in from PCAs as the season begins to end, and at the Yuma Ag Center, DBM can be found on broccoli and cabbage in extremely high numbers. In fact, we were unable to establish 2 acres of broccoli plots due to the extreme damage caused by larvae on seedling plants. The entire 2 acres was essentially destroyed. Trap catches show that DBM are still actively moving (see DBM Trap Network). Thus, any late season brassica crops grown in the Yuma Valley are susceptible to high DBM numbers, particularly with the warmer weather to come. We have also found DBM infesting brassica seed crops, with the larvae feeding on the developing seedpods. Products that are providing efficacy in the field include: Radiant, Proclaim, Exirel, Entrust, Avaunt, Dibrom and XenTari. Avoid applying Coragen, Voliam Xpress, Belt and Vetica due to DBM resistance to these products.

What stinkbug species is shown?

Areawide Diamondback Moth Trapping Network

In response to the recent outbreaks of Diamondback moth (DBM) , Plutella xylostella in Yuma, we have established a pheromone trap network designed to monitor the activity and movement of adult populations of DBM. PCAs have had difficulty controlling DBM in cabbage, broccoli and cauliflower since October. Traps have been placed in Roll, Wellton, Dome Valley, Gila Valley and Yuma Valley in locations where cole crops are presently being grown or in areas where infestations were known to occur this fall.
Click here to see results of DBM pheromone trap network.

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

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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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