Cole Crops
Continue scouting young broccoli, cabbage, and napa cabbage for worms and for flea beetles. The threshold for young plants is a 20% infestation. When plants are young and when caterpillars are young, Bt. should provide excellent control. Flea beetles are typically an early spring, cool weather pest. Thresholds are 1 beetle per transplant or 5 per 10 plants during cotyledon/first leaf stages. There are several effective products for flea beetles, most of which have cross-efficacy with other cole crop pests. Pyrethroids, Torac, and Verimark have activity on cabbage maggot, which should be active now. Those three products are also effective on cabbage whites, and Torac and Verimark are effective on diamondback moth (assuming your local population is not resistant to them).
Asparagus
Scout asparagus for asparagus beetle activity, especially with warm weather allowing beetles to be active. The threshold is 10% spears with beetles or 1-2% of spears with eggs.
Potatoes
Begin scouting potatoes for Colorado potato beetle, especially if near a previous planting. Beetles can fly once the temperatures approach the upper 70’s and low 80’s, which we will get for the first time this weekend.
Greenhouses
Scout transplants for signs of mite and aphid activity. To look for mites, look for small stippling marks on the upper surface of the leaves indicating the potential presence of mites on the underside. Treat the plants while they are hardening off but before transplant. Its easier to treat when on a wagon then when in a large field. For aphids, I like to get on my knees and look up on a sunny day. Aphids generally settle on the underside of leaves, and looking through them will backlight the aphid making them easier to spot.
Snap Beans
Snap bean planting is right around the corner. If tilling a field, and ESPECIALLY if incorporating any organic matter (cover crop, heavy residue, poultry manure), make sure there is an insecticide seed treatment. If not and you have the ability to put something in-furrow, bifenthrin can aid in seedcorn maggot suppression.
Insect Trapping
If you would like to see the hotline brought back, please let us know: owensd@udel.edu or carvelent@gmail.com. Hotline messages would be restricted to 90 seconds, which is just enough time to relay trap counts and maybe a couple of other quick notes.
