Small Grain Disease Forecasting Models

Keys to Successful Fusarium Head Blight (Scab) Management

The window for management of head blight extends from flowering to the early milk stage. While in the boot, the head is protected from Fusarium. After mid-milk, it becomes more difficult for the fungus to infect the kernel and damage is less severe. The most severe head blight epidemics have involved multiple infection periods (environment conducive for FHB development) and cultivars susceptible to spread of the fungus throughout the head. Further information on the biology and management of head blight can be found in the NDSU Extension Bulletin PP804.

High humidity, rain, dew, moderate temperatures, and ultra violet radiation affect pathogen survival, spore production, spore spread, infection process, and disease development. Cold temperatures and dry conditions limit fungal growth and infection. Extended duration of high relative humidity is one of the key factors indicating high risk of infection in the current Fusarium head blight model.

Fusarium head blight (scab) risk assessment models have been developed by the cooperative efforts of epidemiologists based at seven Land Grant Universities and involved in the U.S. Wheat and Barley Scab Initiative. The group used the data from wheat head blight epidemics around the country. The collaborative efforts of these university epidemiology groups continue to increase the scab model efficiency and accuracy level. Although the scab model has been developed based on wheat head blight epidemic data, the wheat scab epidemics often translate into quality problems for barley as well.

Current Scab Model: The Model gives the percent risk of 10% or more scab severity based on weather conditions (humidity, rain, and temperature) suitable for spore development in the week before flowering and suitable environment for infection and disease development. Final scab level will depend on weather between flowering and early dough stages. The model also now allows input by the user on the degree of susceptibility of the wheat variety. The risk map will change with the degree of variety susceptibility to Fusarium head blight.

Research also is ongoing to develop a risk model for DON (vomitoxin) production. The current model provides information on Fusarium head blight infection risk to help producers make timely fungicide applications. Information on currently registered fungicides for North Dakota is provided by the NDSU Extension Service.

Small Grain Disease Forecasting Home
Plant Pathology Department,
North Dakota State University, 306 Walster Hall, Fargo, ND 58105-5012
Web Site:  http://www.ag.ndsu.nodak.edu   Email:  forecast@ndsuext.nodak.edu