David Owens, Extension Entomologist, owensd@udel.edu
Slugs
Slugs are very active right now. While there are no true thresholds for slugs in field crops, a common benchmark is 1-2 slugs per square foot is a level of interest that may (or may not) cause stand issues. I get concerned about fields at this level especially if they have adult gray garden slugs in them as there tends to be a significant number of eggs in the soil that tend to hatch at about the same time. The weather could turn though and be unfavorable to slugs when seeds start going in the ground. Remember, anything that promotes rapid seedling growth, moves residue away from the furrow, and promotes a closed seed slot is important to reducing slug injury potential.
Alfalfa
Continue scouting for alfalfa weevil. Although the majority of the early hatch larvae should be cycling out, overwintered adults emerge and continue laying eggs. In previous years, these ‘spring’ eggs have not resulted in as large a population as the overwintered eggs, but there is still potential for an above threshold population, particularly in fields that had high numbers and were treated with a pyrethroid only. Alfalfa weevil also tends to be less mature in northern areas of Delmarva.
Early Season Moth Activity
This week, we have not been able to check the majority of our traps in time for this edition of the WCU. Joanne Whalen reports 11 black cutworm moths in Sudlersville, MD (this is a low count and not unusual or concerning at this time) and 0 true armyworm. The week before, we had only a handful of armyworm moths in a couple of locations.