Use Data to Select For Fusarium Head Blight Resistance

Tuesday, June 11, 2024

Post-registration assessment of FHB in cereals improves variety selection.

By Emily Croft

Fusarium head blight (FHB) is a fungal disease that affects cereal crops across the Prairies, risking crop damage, lower yields, and reduced quality. The Manitoba Crop Variety Evaluation Team (MCVET) and Manitoba Crop Alliance are working to improve the data available to farmers for selection of FHB-resistant varieties through post-registration analysis.

Anne Kirk, cereal specialist with Manitoba Agriculture and member of the Manitoba Crop Variety Evaluation Team, says that there are a number of ways to prevent FHB infection, but selection of resistant varieties is becoming more popular.

“Varieties get rated for resistance during the registration process,” says Kirk.

“In this process they use inoculated nurseries and assess the reaction of the variety to Fusarium head blight. It’s a Priority 1 disease and there are certain standards varieties should meet to be registered. Farmers want more resistance.”

She explains that post-registration analysis takes this measurement one step further.

“We are looking at conditions under natural infections and under natural growing conditions, so no inoculation and no fungicide. The Manitoba Crop Variety Evaluation Team looks at a number of newly registered varieties or those recommended to be registered in wheat, oats, barley, fall rye, winter wheat, peas, and flax. We observe them over a three-year period.”

With funding from Manitoba Crop Alliance, MCVET has been conducting post-registration analysis for FHB resistance on spring wheat since 2009 and brought barley and winter wheat into the study more recently. There are a few indicators that MCVET uses to assess the resistance of the varieties they are testing.

“For crop susceptibility in wheat and barley, we are looking at the level of FHB infection and watching for DON and Fusarium damaged kernels to see how the tested varieties react during natural infection.”

Deoxynivalenol (DON) is a mycotoxin produced by FHB which can be harmful to livestock in higher levels, reducing the value of the grain as a feed. Currently to detect DON, samples of the grain need to be tested in a lab. Fusarium damaged kernels are the other indicator analyzed by MCVET. They are also known as tombstone kernels, and can appear as small, shriveled, and lighter weight seeds. High percentages of Fusarium damaged kernels can impact grain grading and may cause economic losses for the producer.

The MCVET study is currently using 14 locations to analyze resistance in spring wheat and barley, and there are six sites for winter wheat, due to the generally lower acreage for the crop.

“We can look to see the level of Fusarium infection in different classes of resistance,” says Anne.

“Farmers can also see how specific varieties they are considering performed over the three-year period.”

With trials across different sites in Manitoba, the data generated from this study can also be used by farmers to see how varieties perform in their geographical area. This is important because FHB risk is environment dependent.

“It allows farmers to compare FHB resistance in varieties at their specific location with the relevant environmental conditions and allows for comparison between other varieties at that site,” says Kirk.

Warm and moist conditions during flowering or anthesis create the greatest risk for infection with FHB. Manitoba Agriculture also publishes FHB risk maps with a range of low to extreme based on relative humidity and temperature prior to anthesis to help grain farmers manage their crops.

“They can also look at all moderately resistant varieties and farmers can compare the results within that classification because there will be some range of reaction to FHB within those varieties. The post-registration analysis provides more information to farmers when making variety selections.”

Kirk says that in trials over the last three years, DON has been below the detection limit at some locations due to relatively dry environmental conditions around flowering.

“It’s great to see that these varieties are below the detection limit for DON. That’s good news for farmers.”

She says that this makes it important to evaluate resistance over the full three-year period, to hopefully catch different weather conditions.

Kirk adds, “One other important factor to consider is that low levels of Fusarium make it hard to get a good assessment of how varieties will perform under different environmental conditions.

“It’s not always a fair comparison when looking at variations grown under harder years, because everything looks pretty good in the years when Fusarium infection is quite low.”

Due to this, when evaluating resistance in variety selection decisions, Kirk recommends that producers first review resistance ratings from the seed guide. The results of post-registration assessment can be used to supplement the seed guide ratings by looking at field performance and location.

They hope to continue this project to help producers make better variety selections.

“I think it’s a good idea to continue with the project. There’s always turnover in varieties and always new varieties being registered. If we are looking at varieties over three years, we want a good number of site years to look at yields across Manitoba for both an average and in specific locations.”

They also want to continue looking at the relationship between DON and Fusarium damaged kernels to determine if damage is an appropriate indicator of DON levels without lab testing.

If producers want to get involved and contribute to improved data for variety selection, Kirk says that they are looking for farmers to participate in a survey.

“I would encourage farmers to reach out.

“We are looking for more participation in the FHB survey. We are always happy to have more farmers that want their fields surveyed because it provides better assessment of FHB across the province.”

The FHB survey is conducted in late July or early August. The samples are also analyzed by Dr. Maria Antonia Henriquez at AAFC Morden to determine level of infection and any changes to Fusarium across the province. Better surveillance can improve prevention in the future.

Grain farmers in Manitoba looking to participate in the survey can reach out to Kirk at Anne.Kirk@gov.mb.ca. BF