David Owens, Extension Entomologist, owensd@udel.edu
Greenhouses
This week Cody Stubbs scouted several watermelon greenhouses. Low numbers of mites were observed in 3 of 17 greenhouses. Check plants nearest to entrances and to any weeds growing in the greenhouse or along sidewalls. Look underneath of leaves that show stippling. If a mite infestation gets started in the greenhouse, it puts the field at greater risk for earlier treatment. Mites can be targeted in 4 ways: greenhouse specific miticides (often, but not always different from field branded products), predatory mite application in the greenhouse or on transplant wagons, field-use miticides on transplant wagons, or wait and scout the field after planting and treat when mite populations go above the nominal action threshold of 2 mites per crown leaf on 1/3 to ½ of the plants scouted. Check labels carefully before applying a product to a greenhouse. Make sure that there is no language preventing the use of a product indoors, in a greenhouse, hot house, or enclosed space. Some labels are silent on this matter, and states interpret silent labels differently. Check with your local Extension agent how a state would interpret product use in your specific situation.
Aphids were found in greenhouse tomato and pepper transplants as well. Aphids on tomatoes can be controlled by many of the same products used for early season insect pest prevention (such as flea beetles).
Spotted Lanternfly
Spotted lanternfly eggs are hatching. Be on the alert when moving equipment or plants out of the quarantine areas. Early instar nymphs are black with white spots.