Farmers who blame poor wheat yields and small kernels on the heat or the lack of rain last summer might not have looked far enough down in the plant canopy to find the cause, say plant pathologists.
Manitoba farmers alone lost an estimated $56 million to leaf diseases in 1997.
Andy Tekhauz, plant pathologist at the Cereal Research Centre, surveyed 167 wheat fields in the province last July and August and found an average 10 percent yield loss due to leaf diseases such as tan spot, septoria and leaf rust.
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If the 12,000 farmers in the province grew four million acres of wheat, averaging 35 bushels per acre at $4 per bushel, he estimated they each lost about $8,500.
“I’m sure that every one of these would have preferred to have the $8,500 in their pocket instead of lost in the field,” he said.
Tekhauz said his estimates are conservative because they do not include the loss in quality that comes from small, discolored kernels produced by plants with leaf disease.
“Producers are not always sure when they see damage or symptoms on their leaves, some browning or yellowing,” said Tekhauz, who added problems caused by leaf diseases are often blamed on fertility problems or dry conditions.
He estimated fusarium head blight damage in the province’s wheat crop also caused a seven percent loss in yield, worth $39 million to farmers.
Leaf disease, traditionally associated with wet weather, was spurred to epidemic proportions last summer by high relative humidity, often around 85 percent.
“It seemed like you were in southern Ontario when you woke in the morning,” said Tekhauz, referring to the moistness in the air.
Most farmers in Saskatchewan and Alberta did not fare as badly last summer because of dry weather conditions, pathologists said.
Mike Celetti, provincial plant disease specialist in Saskatchewan, said farmers on the eastern edge of the province saw severe leaf diseases in barley and wheat because of high humidity.
Fusarium head blight was also spotted in the “odd field here and there” in eastern Saskatchewan, said Celetti, who added he is concerned about the spread of the disease.
Ieuan Evans, plant disease specialist in Alberta, said a potential disaster was averted in his province when dry winds blew through in early to mid July.
It’s hard to predict where high levels of disease will strike because conditions change from year to year and field to field, the pathologists said.
Evans said farmers need to increase cereal production on the current number of acres planted if they hope to meet increased demand from the expanding livestock industry on the Prairies.
Extra fertilizer from more livestock manure will lead to more vigorous crops that hold more water, he said.
“One of the consequences of bigger and more lush crops is disease,” he noted.
In the United Kingdom and Germany, where cereal crops are high-yielding and more prone to disease, growers spend $10 on disease control for every dollar they spend on herbicides, said Evans.
