U of S FHB research providing promise for spring wheat and durum producers
By: Dallas Carpenter
Fusarium head blight (FHB) is such a prevalent and destructive problem for Saskatchewan wheat producers that Sask Wheat has made it a research priority, investing millions of dollars into projects studying how to combat the fungus and minimize its damage.
Two of those projects, which were conducted by Drs. Randy Kutcher and Lipu Wang along with PhD candidate Gursahib Singh of the Crop Development Centre (CDC) at the University of Saskatchewan, as well as Drs. Wentao Zhang and Pierre Forbert at the National Research Council, were recently completed. One project tested potential new sources of FHB resistance in spring wheat, while another focused on improving FHB management in durum.
The spring wheat study aimed to identify wheat germplasm with new sources of FHB resistance. Over 4000 different wheat accessions from across the world, obtained from Plant Gene Resources of Canada (PGRC), were screened at the CDCs fusarium disease nursery in Saskatoon in 2016 and 2017. The FHB incidence and severity was assessed for each line and the 400 lines with the lowest incidence and severity were selected to identify their sources of FHB resistance.
In addition, 412 lines of wheat from the International Wheat Research Centre in Mexico were evaluated. Low incidence and severity of FHB was found in 38 of those lines, with two lines showing strong resistance in further testing.
“What we have done is identify PGRC material that looks promising based on field results, and in material from a synthetic cross, which is durum crossed with a wheat relative,” explains Kutcher, who cautions that it is premature to speculate on the effectiveness of the new sources of resistance.
“From both sources, we need further evaluation and characterization before they might be crossed into elite material in a breeding program.”
The information from the study will allow Kutcher and his team to study the genetic structure of the resistance sources further. “This is a first step,” says Kutcher, “which will hopefully lead to the introduction of new sources into breeding programs to arrive at commercially available varieties, so it will be some time before these genes may appear in new varieties.
“The fact that molecular markers are available for some of the genes identified should speed the introgression of beneficial genes into breeding material.”
The study on FHB management in durum focussed on the timing of fungicide application and seeding rates. The results indicated that seeding rate had little impact on the timing of the fungicide application. The researchers also found that dual fungicide applications at the early anthesis and soft dough stages had little additional benefit compared to a single fungicide application at the full flowering stage with 50 percent of the anthers mature.
“Results of the fungicide timing trial in durum suggests that a dual application is not likely economic for commercial growers in most environments under which we tested it,” says Kutcher. “There was marginal benefit to the second (late) application, which we had hoped would lower DON levels, based on work done in another country (Japan).”
Kutcher feels that durum producers would gain the greatest benefit by using conventional approaches for curtailing FHB, with a good crop rotation being a vital part of a well-rounded management strategy.
“With limited resistance to FHB in durum wheat varieties, an equally important FHB management strategy is to adhere to a diverse crop rotation, so inclusion of oilseeds and pulses (and possibly forages), in at least a three-crop sequence is recommended,” says Kutcher.
“A diverse rotation, coupled with fungicide application when the risk of disease is high due to disease conducive weather conditions at flowering (rain, high humidity and moderate to warm temperatures) are key.”