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Surveys Show Low Levels of Fusarium Head Blight Infection on the Prairies in 2007

by 5m Editor
13 October 2007, at 12:25pm

CANADA - Surveys conducted across western Canada this year show the level of fusarium head blight infection in cereal crops to be light. However, the anomaly is that in the areas most prone to the disease winter wheat crops, not spring wheat crops, have been most affected.

Fusarium head blight is a fungal infection that primarily affects cereal crops. The main concern with Fusarium head blight is that certain species produce mycotoxins which make the grain unpalatable.

“The species that we find in western Canada causing the great majority of disease is a species called fusarium graminearum,” explains Randy Clear, a mycologist with the Canadian Grain Commission (CGC).

Pigs Particularly Sensitive to Fusarium Graminearum Mycotoxins

Dr. Jim House, an associate professor with the University of Manitoba’s Department of Animal Science adds the organism results in higher levels of fungal metabolites that are produced on the grain itself. “In particular what we’re concerned about in Manitoba is a mycotoxin called deoxynivalenon or DON.” He notes research over the past couple of decades has shown that DON has a significant effect on reducing feed consumption, primarily in pigs.

Younger pigs tend to be a little bit more sensitive but the data is quite variable, says Dr. House. “One of the recommendations that we typically give is to avoid using infected grain in areas where feed consumption is critical such as with baby pigs and the breeding herd, in particular the sow herd.”

Based on historical data backed by research at the U of M, Dr. House estimates for every one part per million of DON in the finished ration producers can expect a reduction of about seven and a half percent in feed intake relative to control diets without any DON in it. It’s recommended that DON levels are kept lower than one part per million in finished rations.

He adds, where grains have elevated levels of DON, the recommendation is to dilute down the contaminated grain with clean grain to bring the level below one part per million. “What we're really concerned about is the final concentration in the finished ration.”

Infection Levels Highly Weather Dependent

Levels of infection will depend on several factors, primarily the weather and the presence of disease inoculum in the soil. Traditionally fusarium has been most prevalent in Manitoba, primarily the Red River Valley where the disease has become endemic, extending into southwestern Manitoba and to a small extent into southeastern Saskatchewan.

“It depends very much on the type of rainfall and amount that we get during the flowering period,” explains Penny Pearse a provincial plant disease specialist with Saskatchewan Agriculture and Food.

Saskatchewan Agriculture Assesses Disease Prevalence

In cooperation with the Saskatchewan Crop Insurance Corporation, Saskatchewan Agriculture and Food conducts an annual survey to monitor where fusarium is occurring in the province, whether there are changes in virulence and the type of species present. Samples are collected during the heading stage, when the seeds have started to form and about 240 wheat, barley, oat and corn fields were sampled across the province this year.

Pearse observes, “The good news is that we aren’t seeing very high levels of fusarium head blight and this is what we’ve been seeing for the last few years. So overall our severity levels are quite low.”

She says that wheat in Saskatchewan averages a severity of 0.2 percent, meaning about two out of one thousand kernels may have some type of fusarium infection. For barley the Saskatchewan average is around 0.6 percent and for durum it’s less than 0.1 percent.

Pearse notes that there is very little fusarium graminearum in Saskatchewan and that it tends to be restricted the southeastern portion of the province and the irrigated areas.

Cereal Research Centre Monitors Infection Levels in Manitoba

In Manitoba, Agriculture and Agri-Food Canada’s Cereal Research Centre conducted four separate fusarium head blight surveys, one in winter wheat, one in spring wheat, one in barley and one in oats. Plant pathologist Dr. Andy Tekauz notes scientists focus on the cereal growing areas and tend to concentrate a little bit more in the Red River valley and in southern portions of the province.

“This year is I would say overall that the levels, if we look at say a ten year average, are perhaps a little bit lower than average.”

“Generally speaking the southern most portions of the province close to the United States border were those that seem to have been more affected than other areas. We think that this is likely because those crops were planted earlier. It seems that the earlier planted crops this year suffered somewhat more from fusarium head blight than those that weren’t planted during that first window of opportunity.”

Fusarium Graminearum Entrenched in Manitoba

Dr. Tekauz recalls in 2006 we probably had the lowest levels of fusarium head blight since 1993 when we started looking at it intensively. “I think the point that we need to remember and to stress is that that disease is endemic here and that means that it’s going to be here for some time to come and when ever conditions are right for it to manifest itself we’re going to see it.”

Fusarium Graminearum Rare in Saskatchewan and Alberta

Pearse notes, Saskatchewan is naturally drier during the point in the season when crops are most susceptible which helps limit the amount of disease. However, she acknowledges, with changing climates and with higher amounts of inoculum in the fields, fusarium could also start to increase in Saskatchewan.

Canadian Grain Commission Survey Focuses on Wheat

As part of its annual harvest survey the Canadian Grain Commission looks at all grain types that come in from across the prairies. However Clear points out, when it comes to fusarium, the CGC concentrates on the wheat crop.

“When there’s fusarium head blight in the crop there’s visible damage which we call fusarium damaged kernels (FDK) and they’re easy to spot in a sample. It gives us a good idea of the areas have been affected and the degree of infection.”

He says this year was good year in terms of head blight, especially in the spring wheat. The surprise this year was in winter wheats. Winter wheats usually flower during the drier period of the growing season but the wet weather in May and June pushed fusarium levels in the red winter wheat higher than would have traditionally be seen.

“The areas that have traditionally been the highest levels are once again the higher levels and that would be the Red River Valley of Manitoba,” he says.

Management Eases Risk of Fusarium Infection

Pearse stresses that the management of fusarium head blight includes both the use of clean seed low in fusarium and good crop rotation. Although there are no wheat varieties resistant to fusarium head blight, there are some that are less susceptible that should be used in areas where there is fusarium. Fusarium also tends to develop when cereal grains are planted back to back or every second year and also under irrigation.

Dr. Tekauz concludes that from the research standpoint the effort to address fusarium head blight continues. “There’s a tremendous amount of work going on on the breeding side, in particular in trying to develop improved varieties that will resist fusarium head blight and also resist the accumulation of the mycotoxin DON.”

5m Editor