Agronomic Crop Insect Scouting

David Owens, Extension Entomologist; owensd@udel.edu

 

Early Season Moth Activity
This is the last week of early season moth trapping, a big thank you to all the host farmers for letting us put up and service traps. Please let me know if you observed either pest in your fields causing damage, when, and what the field conditions were. Overtime with your feedback we can figure out just what pheromone traps for armyworm and cutworm mean.

Early Season Moth Activity

Trap Location True Armyworm per night Black Cutworm per night
Willards, MD 0 0.6
Salisbury, MD 0 2.3
Laurel, DE 0 7.7
Seaford, DE 0 2.3
Bridgeville, DE 0 0.1
Harrington, DE 0 2.6
Smyrna, DE 0.7 2.3
Kenton, DE 0 0.4
Pearson’s Corner, DE 0 0.4
Sudlersville, MD 0 0.9

 

Soybean
It can be tempting to put in a cheap insecticide with a post emergence herbicide spray, but is it worth it? Vegetative, full season soybeans with good plant stands can withstand a beating without losing yield. Some studies from southern states indicated that non yield-limiting defoliation can be greater than 66%. Current thresholds are very conservatively set at 30%. Bean leaf beetles are active, in most cases they are not at threshold levels of 2 beetles per plant + stand reduction. Other insects that may be present in soybean fields early include thrips (cause a cosmetic injury) and thrips predators such as Orius and minute pirate bug. Later in the season, both will feed on Lep eggs and early instar worms. Predators are slow to build up their populations and are very sensitive to insecticides. Bottom line, if in doubt, take a quick look in a few spots in the field. Doing so could very easily save a spray, save some predators, and save insecticide money.