Potatoes in Canada

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Manitoba potato disease report: Sept. 3

 

Sept. 3, 2015, Carman, MB – Manitoba currently has no reports of natural infection by late blight, writes Vikram Bisht, with the potato and horticultural crops department at Manitoba Agriculture, Food and Rural Development, in the latest potato disease report.


September 3, 2015
By Dr. Vikram Bisht/MAFRD

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The only late blight in the province is an inoculated late blight control experimental plot in an area with no commercial potato production.

Crops are doing well throughout the province and weekly accumulated DSVs indicate moderate risk conditions for late blight disease, if the disease inoculum were present.

There was a call earlier this week, from a home gardener in eastern Manitoba about suspicion of late blight. A visit to the site showed the gardener’s tomatoes were affected by Septoria and early blight, and nearby potatoes were also severely desiccated by early blight and probably Verticillium wilt. Thus it was a false alarm. The good thing is that the general public is aware of the need to report such a disease, which could affect the commercial potato industry. But we have to get the home gardeners to be more aware of late blight symptoms.

The forecast for the coming few days is very warm and dry, which should keep the late blight risk at low levels. However, it is still prudent to keep scouting in low lying and sheltered areas and keep the foliage covered with protectant fungicide. The early blight incidence continues to be low in most fields, especially in Russet Burbank.

There is a forecast of frequent rain days towards the weekend. These conditions could be favourable to pink rot infection. Use of phosphorus acid as a post-harvest treatment should be considered for fields with prior history of pink rot issues.

In a number of potato fields, it appears that the European corn borer has affected a substantial number of plants, leading to desiccation of part or all of the plant. This may have impact on sizing of tubers in the affected plants.