Pierce Paul, Ohio State University plant pathologist, says growers who planted resistant wheat varieties and applied a fungicide at flowering had lower levels of scab and vomitoxin in their wheat in 2009 than those who planted susceptible varieties.
“As you prepare to plant wheat this fall, scab resistance should be a top priority on your list,” says Paul. “In the past, there were very few Ohio-grown winter wheat varieties with decent scab resistance and some of those varieties yielded poorly or did not grow well under our conditions. Today we have far more varieties with very good scab resistance in combination with very good yield potential.”
He says no variety is completely resistant or immune to scab, so if conditions are wet and humid during flowering, even varieties considered resistant will develop scab and become contaminated with vomitoxin. However, disease and toxin levels will be lower in resistant varieties than in susceptible varieties.
“In addition, with a scab-resistant-variety growers will likely see greater benefit from the use of fungicides if scab develops,” says Paul. “In general, relative to the most susceptible varieties, scab and vomitoxin reductions tend to be much higher when fungicides are applied to resistant varieties than to susceptible varieties.”
Paul says seed treatments can play an important role in achieving uniform seedling emergence under certain conditions. “Seed treatments can protect seeds or seedlings from early season disease and fungicides are available to provide such protection,” he says. “However, seed treatments should not be considered a cure-all for the selection of poor-quality seed lots. Seed treatments will not increase poor germination due to excessive mechanical damage, poor storage conditions, genetic differences in variety, or other damage.
Head scab and Stagonospora glume blotch were at high levels in many Ohio and other Midwestern fields this year. Therefore growers need to limit losses due to these and other seed-borne pathogens by treating seed. Be especially concerned that saved seed may be contaminated, warns Paul. “If head scab or Stagonospora was present at high levels in your wheat field, do not use that grain for seed,” he says. “These seed-infesting fungi will contribute to poor-quality seed resulting in reduced yield and lower test weight.”