Headblight continues as problem in Idaho spring wheat
By John O’Connell
A cereal crop disease expert is concerned that Fusarium headblight has posed a significant problem for growers for yet another season, and that it’s traveled further away than she expected from corn fields, which host the most prevalent strain of the fungal pathogen.
University of Idaho Extension plant pathologist Juliet Marshall said the Magic Valley and the Rexburg and Sugar City areas were hardest hit by headblight, which reduces yields and creates the DON toxin, known to make people and animals sick. She estimates between 5,000 and 10,000 acres of spring wheat were affected, in a few cases, miles away from corn.
“The fact that some of the disease is showing up in areas that are not real close to corn and the fact that it’s started to be a consistent issue is a major concern to me,” Marshall said.
Prior to the increase in Idaho’s corn acreage to support its growing dairy industry, about two-thirds of the state’s headblight was caused by Fusarium culmorum, spread in plant residue and soil. Fusarium graminearum, which creates airborne spores that thrive on corn, is now culpable for at least two-thirds of Idaho’s headblight.
In 2009, Idaho farmers planted 300,000 acres of corn, according to USDA. This season, they planted 350,000 corn acres, compared with 317,000 acres of potatoes.
Marshall saw some fields this season with upwards of 7 parts per million of the DON toxin and said grain buyers have docked growers anywhere from 45 cents to $1.50 per bushel as a result of headblight.
She said the hard white spring wheat Klasic was the most affected variety this season. She saw no winter wheat infections. Wheat plants are most susceptible to headblight at flowering, and Marshall explained winter wheat tends to flower when conditions are too cool for headblight.
To mitigate the risk of infection, Marshall said some growers are planting resistant wheat varieties, such as the hard red spring wheat Volt. Next spring, she said the first certified seed will be available of UI Stone, a resistant soft white spring variety.
Marshall also advises growers to spray a fungicide on spring wheat at flowering, though some growers who sprayed still had trouble with headblight.
“Fungicides reduce impact of the DON toxin, but they do not give you a 100 percent guarantee of control,” Marshall said.
Marshall said growers can improve fungicide performance by seeding wheat at higher rates, leading to more uniform flowers that are easier to spray. Rotation can also help if growers break up grain and corn cycles with broadleaf crops.
American Falls grower Kamren Koompin said his farm conducted trials in spring wheat fields following corn this season to gauge the susceptibility of varieties, treating some acreage at flowering and leaving other acres as untreated controls. They found that the hard white spring wheat Paloma was highly susceptible, losing 20 bushels per acre to headblight in untreated fields.
“We probably won’t be planting Paloma again,” Koompin said, adding his farm likes to plant wheat after corn for the improved water infiltration.
However, the hard white spring wheat Snow Crest showed resistance, with its untreated acreage yielding better than even the treated Paloma. The Koompins also had good luck with the hard red spring wheat Cabernet.