August 1, 1996 * Vol . 6, No. 7

SFU tests new controls for potato blight

A strain of the potato blight now threatening crops in eastern Canada is only a sizeable rainfall away from infecting B.C. potatoes.

Prof. Zamir Punja, director of SFU's centre for pestology, is currently involved in a three-year study into ways of fighting the fungus which destroys potatoes and caused the infamous Irish potato famine of 150 years ago.

Punja says the fungus only needs periods of cool, rainy weather to re-emerge as a problem in the Fraser Valley or elsewhere in B.C. The fungus is impossible to eradicate because it is easily spread by the wind, or through transplants. It also lies dormant in the soil during dry weather, poised to infect nearby plants with the arrival of the appropriate, wet conditions.

Punja says tomatoes are also under serious threat because both plants are susceptible to the same strains of fungus. "That's why you can't grow tomatoes in Pemberton where farmers produce large quantities of seed potatoes," he explains.

"In 1993 we had a bad spell where fungus ravaged local potato crops," recalls Punja. "It was so bad, some farmers thought they would never be able to plant potatoes again. But they did and the weather has been co-operating lately."

Punja says the only weapons that farmers currently have are chemicals, but the fungus is so virulent in particularly wet conditions that control may require treatments every few days. Not only is this expensive, but applications are not always effective for control.

The natural barrier known as the Rocky Mountains means that the fungal strains currently threatening eastern potato crops are different than those in B.C. Punja says his research team and others are investigating a number of new fungicides which look promising for B.C. strains, but no breakthroughs are expected anytime soon.


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