Ontario potato crop update
By Eugenia Banks
May 4, 2016, Ontario – The early-planted potato crop in the Leamington area is sprouting nicely with strong, healthy sprouts. In the Simcoe-Delhi area, the second earliest area, planting is progressing well, according to the potato crop update from Eugenia Banks.
A few seed lots coming from other provinces had high incidence of common scab and silver scurf.
Seed-borne silver scurf
Silver scurf is a serious problem for fresh market growers. The fungus causes silvery brown lesions that can grow and join together covering most of the skin of the tuber. The fungus does not survive for very long in the soil, but does move from infected seed to daughter tubers. The variety Superior is very susceptible to silver scurf. If infected seed is planted, plan to harvest the crop as soon as the skin is set. Leaving potatoes in the ground after skin set stimulates the development of the fungus and results in more blemishes. Silver scurf also spreads easily in storage. High humidity increases sporulation, and air circulation in the pile spreads the spores to healthy tubers.
Quadris in-furrow and Emesto Silver as a seed treatment are labelled for silver scurf. Post-harvest applications of phosphorous-acid based fungicides have been reported to reduce the incidence of silver scurf.
There were several outbreaks of late blight this year on potatoes and tomatoes grown in Florida. South Carolina has also reported late blight on tomatoes. All of the outbreaks were caused by US 23 strain. According to the potato pathologist at the University of Wisconsin, US 23 is susceptible to Ridomil.