David Owens, Extension Entomologist, owensd@udel.edu
Congratulations to Chris Cawley for accurately identifying both Phytophthora and corn earworm in the last two weeks’ GTP.
Scattered earworm have been reported in soybeans in low and isolated, well below threshold numbers. First and Second instar earworm have an orangish, bumpy appearance with a black head capsule. Once they molt into the third instar, they take on a more typical appearance: orange head capsule, green, black, or yellow body, and a triangular appearing anal segment.
corn earworm
For Phytopthora, this from Dr. Alyssa Koehler: The cucumber in this photo is suffering from an infection with Phytophthora capsici. Disease from P. capsici can occur on cucumber, zucchini, summer and winter squash, watermelon, cantaloupe, pumpkin, pepper, tomato, etc. Typically, rain will splash spores from the soil up onto the foliage and fruit causing infection. After fruit becomes infected, it may take up to 2 days for the infected tissue to develop a dark green, water-soaking. By 3 days, white spores may form on the fruit surface, followed by fruit rot. Due to this disease cycle, it is possible to harvest healthy-appearing cucumbers, which deteriorate days later in storage or transit. If Phytophthora is found, remove diseased plants and surrounding healthy-looking plants. Since Phytophthora can travel in water, it is best to avoid using surface waters and drip irrigation is preferred to overhead. Fungicides such as Elumin, Orondis Ultra, Orondis Opti, Revus, and Presidio can be applied, taking care to rotate FRAC groups.
Phytophthora capsici.