David Owens, Extension Entomologist, owensd@udel.edu
Congratulations to Erin Eure for correctly identifying the three causes of late season watermelon issues: Insect feeding (most likely cucumber beetle in this case), Phytopthora, and Rain-caused splitting. We received about 5 inches of rain in one week at Carvel, and our field does not have good surface drainage. These two factors together promote both the rain-splitting and the Phytopthora. Second generation cucumber beetles are emerging. Adults like to hide from direct sunlight on hot days, hence the reason why this fruit is scarred on the shaded underside but not on the ground spot. Beetles hiding and feeding on the fruit next to the plastic.
Guess The Pest! Week 21