LACOMBE, Alta. – Conservation tillage is gaining popularity across the Prairies but a downside could be more fungal diseases in crops like barley.
Kelly Turkington, plant pathologist with Alberta Agriculture at the barley development centre at Lacombe, screens for problems like smut, net blotch and scald. The centre also examines how these diseases affect production.
Most plant diseases in Alberta are caused by fungi and a comparative few come from bacteria or viruses. The same pathogens can strike a plant at various stages of its life, causing different problems.
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Harboring disease
Conservation tillage promotes leaving straw residue on fields to hold back erosion. But that residue may be the host for net blotch and scald, carrying the disease over from one year to the next.
Scald causes oval lesions with a brown circumference on leaves and leads to significant yield losses. Net blotch causes an elongated lesion that follows the vein of the leaf. Smut attacks a plant and produces black spores on the leaves and heads of grains.
A 1995 study of conservation tillage in Alberta showed an overall increase in net blotch in zero and minimum tillage systems because the disease is carried in old barley straw. If fields are rotated, the incidence of disease drops. Chemical control also helps.
The survey is being repeated this year.
Growing patterns
The centre has also examined the variation between years, climate and regional growing patterns, as well as crop rotation and disease resistant varieties.
“These factors are probably going to have much more effect on the level of disease as compared to the type of tillage system used,” Turkington said.
“By using a variety with intermediate level of resistance, producers who are using zero tillage can keep their disease levels down to levels that were comparable to producers using conventional tillage.”
The survey suggests root diseases may be reduced with conservation tillage. Common root rot is caused by the same pathogens as scald or net blotch but occurs at a different stage in the plant’s life.
