The late blight fungus can attack the leaves and stems of potatoes, tomatoes and peppers. As such, home gardens pose a significant threat to commercial potato growers. Leaf symptoms often appear as large, blackish to grey coloured lesions, sometimes surrounded by a pale green to yellow border. On potato stems, dark black lesions will be found on the upper portions plants.

If you find any infected plants, they should be carefully removed and placed in plastic bags, and left in direct sunlight. Avoid shaking the plants when “bagging” as this may dislodge the fungal spores that spread the disease. Once the plants are dead, the fungus is also destroyed.

Late Blight is a devastating fungal disease responsible for the Irish Potato Famine and can cost the Prince Edward Island economy many dollars. Individuals planting potatoes, either farmers or gardeners have a responsibility to be knowledgeable and to use good stewardship control measures.

In a garden, rapid destruction of both the foliage and fruit occurs, plus the disease can continue to spread if adequate control measures are not adopted. P.E.I. has ideal growing conditions for this fungus with our high humidity in the form of dew, rain or fog and moderate day temperatures and cool night temperatures. As a result, the fungus can be wind swept from a home garden to a commercial potato field very quickly.

Gardeners are encouraged to carry out disease prevention measures by applying late blight control products that are available at most garden centres.

For more information, gardeners are encouraged to visit our web site at www.gov.pe.ca/go/hgblight and obtain a copy of the fact sheet “Late Blight Control in the Garden” or send a plant sample to your local Access PEI office or directly to the Plant Health & Diagnostics Lab in Kensington.

The department also reminds commercial growers that all culls should now have been disposed of. Cull potatoes are the major source for new late blight infections.