Sep 16, 2016 - Potato Disease Report #15

Dr. Vikram Bisht,
Plant Pathologist, Potato & Horticultural Crops,
Manitoba Agriculture

Harvesting is in full swing.

Seven-day accumulated DSVs at various weather stations suggest that the risk for late blight is generally low. Many of the infected leaves are not showing spoulation on the underside.
Fig1 & 2: Late blight infection on the upper side of leaf, showing no sporulation on the underside of the same leaf. Photo: Vikram Bisht.

The current weather forecast is for possible rains and cloudy conditions in the coming few days.

There was a potential for frost in some areas. Below is the map for the minimum air temperature, prepared by Manitoba Agriculture-AgWeather program. Similar maps will be prepared when frost warning may be needed. Average date for most of the potato growing areas appears to be around the 3rd week of September.
Map 1. Minimum air temperature on Sept 13-14, 2016

Map 2. Average date (1981-2010) of first frost (0°C)

Wet spots of a field should be either left in field or harvested at the end of that field so that the tubers are at the front of the bin and easily accessed if need arises.

This will be the last regular disease reporting for the season.

I thank all the agronomists who provided input during the season. Wishing all a safe and great harvest season.

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