Seems that insect pests in fall produce crops are like a box of chocolates, you never know what you’re going to get. And this year is particularly interesting. Whitefly pressure has been the lightest I’ve seen in several years. There are exceptions, particularly in areas near alfalfa and where cotton is still being defoliated. Bagrada bug has also been very light this fall, although we are now beginning to pick up a fair number in broccoli plots at the Yuma Ag Center (YAC). Not sure why the numbers are lighter this year, and why they are just now beginning to show up in numbers. I have had reports that they are also showing up in a few areas in Coachella Valley. On the flip side, flea beetle activity has been very heavy this fall and populations remain very active in some locations. At YAC, flea beetle activity remains heavy and can be found on all lettuce and cole crops of all sizes. Worm activity has been erratic this fall, but there are plenty of them around. Beet armyworm pressure was very heavy about 3 weeks ago, subsided a bit last week, and now are coming on heavy again. Egg masses can readily be found on lettuce and broccoli. Perhaps most surprising has been the unusually heavy cabbage looper pressure the past few weeks. We’re averaging 3-4 larvae /plant in many of our efficacy trials, and egg lays remain steady. Have also had reports of diamondback moth on transplants in some areas. We can only find them on low numbers on direct-seeded broccoli. The good news is that our trap counts show that corn earworm moth activity is very low -but definitely don’t forget about them as the head lettuce begins to fold in. With the warm weather expected to continue for the next week or so, I would not anticipate the worm pressure to let up much. Thrips have also been unusually active so far this fall, showing up a few earlier than normal. At the YAC, we’re picking up quite a few bean thrips (see image below) adults. The adults are heavily scarring up the plants, but can be controlled with Radiant and Lannate. It seems like they dispersed into the Yuma Valley following that low pressure system that moved through the area last week. Finally, we’ve been picking up winged-aphids in our trapping network for the past 3 weeks, a bit earlier than normal. I have observed winged cabbage aphid and cowpea aphids on lettuce, and although we’ve yet to find any green peach aphid winged adults, I observed this week a few green peach aphid nymphs colonizing broccoli at YAC. Given that cool weather and windy weather we experienced recently, this is not surprising. Crops treated with imidacloprid should prevent significant colonization on younger crops. But keep your eyes open for aphids on older cole crops, particularly where the imidacloprid residual may be declining.

Bean Thrips

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Purslane Sawfly

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

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To contact John Palumbo go to:jpalumbo@ag.arizona.edu

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.