The introduction of new disease-resistant lentil varieties raises the question of whether producers will still have to use fungicide.
The jury is out.
Al Slinkard, head of pulse crop breeding at the Crop Development Centre of the University of Saskatchewan, believes lentil spraying will become almost a thing of the past.
He said the Prairies have experienced seven consecutive years of relatively cool, moist summers ideal for development of ascochyta disease.
“It required at least one spray … and sometimes two sprays and that cost $10 an acre (for chemicals) for each application plus application costs,” Slinkard said.
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“Some people disagree with me … but I believe they will not have to spray with Bravo unless they do something like planting lentils on lentil stubble where there is a heavy inoculum load that the resistance breaks down.”
“While ascochyta-resistant varieties will be a boon to Saskatchewan growers, they perform best when weather conditions are normal and as long as rotations are maintained,” said Ray McVicar, special crops specialist with Saskatchewan Agriculture.
In moist years when the disease inoculum level is high, infection can penetrate a variety’s genetic defences.
“In an iffy weather year, there is nothing wrong and plenty right about using a fungicide to reinforce the resistance to the disease. The fungicide should be applied at the very early flowering stage.”
Test-plot scale research carried out by Robin Morrel, a biologist at the University of Saskatchewan, showed that on an ascochyta-resistant lentil variety, an early season, low rate application of the fungicide chlorothalonil would increase yield more than enough to offset the cost.
Slinkard has asked that tests be done on a field scale.
“I feel confident that they won’t get any additional benefit when the inoculum load is low,” he said.
