Researchers from University of Idaho inform growers about Hessian fly, spore trapping and soil borne diseases

On January 29, 2020, 40 people gathered in the University of Idaho tent at the Canyon County Fairgrounds, during the second day of the Western Idaho Ag Expo in Caldwell, ID, for presentations on Hessian fly, spore trapping and diagnostics for soil borne diseases.


Dr. Arash Rashed told the audience that Hessian fly is a challenge as there are multiple genotypes of the flies, their range is expanding, there are recent reports of damage to winter wheat (they used to be a concern in spring wheat only) and spraying pesticides doesn’t solve the problem since the adult flies only live two to three days. The most recent incidence in southwest Idaho including Caldwell was in 2015. Dr. Rashed said the best prevention is crop resistance. Cultural practices such as proper rotation and late-fall planting (especially after mid-October, where possible) can contribute to reduced levels of damage. There is no recent economic impact study. While there are several Hessian fly resistant spring wheat varieties are available to the Pacific Northwest producers, no club wheat variety is resistant yet. Working with the University of Idaho and Washington State University wheat breeding programs, Idaho Integrated Pest Management Laboratory continues to screen varieties and breeding lines to gauge resistance in both controlled and field situations.


Dr. Carlos Pizolotto spoke about disease modeling including resistance, the existence of a pathogen and the environmental effect on growth. He said the key equation is “Environment, pathogen and host = disease.” Spore trapping helps to predict outbreaks and determine the distribution of spores and spread of disease. There is a 15-site spore trapping network in Idaho with collection every Monday and to get DNA to lab every Tuesday. He brings samples in from the traps in the network after seven days, looks at DNA and tests it. Weather data is a factor that is considered. Dr. Pizolotto previously studied wheat blast in Brazil and Kansas.



Lara Brown, a master’s student at the University of Idaho in Parma, spoke about diagnostics for soil borne diseases, which cause biological stress that is likely to lead to yield loss. She talked about a cereal survey in 2019, which included 48 wheat fields (16 in the Treasure Valley, 19 in eastern Idaho and 13 in northern Idaho). Four key disease species were found including Rhizoctonia, various forms of Fusarium, Microdochium and Pythium ultimum. In winter 2018/19, there were greenhouse trials on Ovation, which found Rhizoctonia. It is important to consider the impact of soil borne diseases on cereals and subsequent crops in order to prevent decreases in yield.