EDMONTON Ñ It’s too soon to accurately predict which plant diseases will cause damage in 2005, but Kelly Turkington said the picture will be shaped by last year’s diseases and farmers’ plans for this spring.
Turkington, a research scientist with Agriculture Canada at Lacombe, Alta., said the big plant diseases in Alberta last year included ergot, sclerotinia stem rot and cereal leaf diseases.
He told the FarmTech 2005 conference in Edmonton that fusarium head blight is starting to appear in some of the irrigated areas of Alberta, mostly on durum. Turkington said irrigation management will be a key control strategy for producers.
Read Also
Message to provincial agriculture ministers: focus on international trade
International trade stakeholders said securing markets in the face of increasing protectionism should be the key priority for Canada’s agriculture ministers.
“It’s often where there’s durum on durum and where producers are really pushing the water on the crop. They can look at limiting the infection and downgrading by irrigation management. If they terminate irrigation prior to anthesis (flowering), which is a key time for infection, the trick is to cut the water off to limit the disease, but not enough to limit production.”
Turkington said he encountered the cereal leaf diseases scald and net blotch, especially where producers were pushing rotations.
Fungicide applications too early were not effective.
“Our two most consistent treatments were either the full rate at flag leaf emergence or the split application, with a half rate at the flag leaf stage and a half rate at heading. With a very early application, we didn’t see as consistent control. The take-home message is you want to target that flag leaf stage, to protect the flag leaf and the next leaf down.”
Turkington said strip rust in wheat has blown in from the United States and most Canadian wheat varieties are susceptible.
As with scald and net blotch, using a foliar fungicide to protect the flag leaf is the best strategy.
Sclerotinia stem rot can be effectively controlled, but the foliar fungicide must be applied before symptoms are visible. Turkington said a routine fungicide application on canola is questionable because the disease severity varies each year. But when fungicides are applied, good coverage is essential.
“Don’t just focus on the petals. Look at putting that chemical down into the canopy, on the leaves, into the leaf axils and bases. You can do that by increasing water volumes. You can also look at split applications, tailoring your fungicide application to your risk,” he said.
“If the risk of disease is high and your crop yield potential is high, you can look at two applications of fungicide, one at early bloom and one at full bloom. If conditions turn dry after the first application and you think the risk is going down, you can stop there and not put on that second application.”
With sclerotinia, even with long rotations and good field sanitation, there’s still a risk.
“Wind dispersal of spores means even if your rotation is good, if a neighbour has pushed his rotation, it can blow in,” he said.
Maintaining a balanced fertility program, often associated with crop yield and quality, can also reduce disease risk.
“A fertilizer deficiency can predispose plants to attacks or damage. Excessive fertilizer may promote the growth of a dense, lush canopy that favours diseases. A balanced fertility program helps promote a healthy root system and vigorous plant that can work through infections,” he said.
“A healthy crop may not prevent a disease from developing, but it can help the plants tolerate and compensate for the disease, maintaining yield and quality.”
