|Jun 15, 2012 - Disease Update #4|
By Dr. Vikram Bisht, Plant Pathologist - Potato & Horticultural Crops, Manitoba Agriculture, Foods & Rural Initiatives
Good soil moisture and warmth is helping the potato crop move along well. Many of the early planted fields have foliage touching within-rows. Later planted fields are emerging well. By this time most fields may have herbicide application done.
There is a forecast for wide spread rains in the province in the coming week. It will be a good strategy to have the plants protected before the rains. If the plants are small, low rate of a protectant contact fungicide could be considered. Fields or part of fields wind-protected (surrounded) by trees could have micro-climate more conducive to late blight development for a longer period; for such fields full rate should be considered. Follow fungicide label directions for appropriate use of the product.
A few fields appear to have herbicide drift affected plants along the border with another crop. It is important to take steps to minimize herbicide drift issues when spraying.
More cases of late blight are being reported from Florida, mainly on tomato and US# 11 (metalaxyl resistant) strain has been also found on tomato.