This will be our last regular Pest Alerts of the season thanks to grant funding provided by the Northeastern IPM Center for 2014 and 2015. Funding paid for field scouts in Rhode Island, Massachusetts and Vermont to scout vegetable farms in each state and publish findings to a regional farmer audienceeach week throughout the season. Special thanks goes to: Andy Radin and Lauren Breene at URI; Ann Hazelrigg, Mollie Klepack and Anya Rose at UVM; and Ruth Hazzard, Sue Scheufele and Lisa McKeag at UMass for diligent scouting and careful reporting.
Cucurbits: Cucurbit downy mildew was confirmed on cucumber in Hampshire Co., MA this week and on pumpkin in Franklin Co., MA last week. No CDM was found during scouting visits in Worcester and Middlesex Co., MA. According to the CDM-IPM Pipe forecast, most of MA is at a moderate risk of infection and CDM specific fungicides should be applied now in rotation every 5-7 days.
Cucurbits: Cucurbit downy mildew was confirmed on pumpkin in Franklin Co. MA this week. It has been reported on cucumber, cantaloupe, acorn and summer squash in other states, but all cucurbits should be considered at risk. Growers in MA should spray cucurbits on a 7 day rotation with oomycete specific materials. Fungicides registered for Downy Mildew include Tanos, Zampro, ProPhyt, Curzate, Forum, Gavel, Presidio, Ranman, Previcur Flex, Pristine, and Reason.
Cucurbits: Powdery mildew is well established in older MA and RI cucurbit fields and is starting to spread into new plantings. Conditions favoring infection include a dense plant canopy, low light intensity, high nitrogen fertilization, relative humidity >50%, and 68-80° F.
Solanaceous crops: Late blight continues to spread, with new outbreak confirmed this week from a tomato field in Worcester Co. MA. Several samples from MA were genotyped as clonal lineage US-23, which is generally sensitive to methanoxam (Ridomil) and attacks both tomato and potato. For a map of late blight reports and photos of symptoms, see usablight.org.
Table 1. European corn borer (ECB), fall army worm (FAW), and corn earworm (CEW) trap captures for the week ending 7/17/14.
Cucurbits: Frequent rains and humid weather are highly conducive to development of Phytophthora blight. Scout low-lying, wet, fields or fields where the disease has previously occurred. Plow under any areas that are infected, along with a non-infected border area, to slow the spread of this disease.