ISSUE 7 June 17, 2004
FUSARIUM HEAD BLIGHT RISK AND WHEAT GROWTH STAGES
In parts of ND and MN, the most advanced wheat crop may be at risk for Fusarium head blight (FHB = scab). The winter wheat in some areas of ND is in the flowering stage and spring wheat fields in the SE and EC counties are either in or fast approaching the heading stage. Producers in these areas need to keep alert to the risk of late season leaf diseases and Fusarium head blight. The NDSU Small Grains disease forecasting web site:
currently (June 16) indicates a high risk of Fusarium head blight (FHB) in many eastern counties (see figure). Growers need to be watching this web site closely as their crop enters the early flowering stage, as well as watch the weather forecast following flowering.
The FHB risk forecasting site out of Penn. State ( http://www.wheatscab.psu.edu/riskTool.html ) also currently indicates some high risk areas in eastern ND, but indicates a smaller area of high risk. From a comparison of the two web sites on a daily basis, it appears that the Penn State is a little more conservative in prediction of risk than the NDSU site using the NDAWN stations, primarily because the Penn State is extrapolating risk with calculated weather on a 20 mile radius whereas the NDSU site is extrapolating risk over a longer distance, between NDAWN stations.
SMALL GRAIN IPM SURVEY UPDATE 06/16
Tan spot was the most common disease observed in wheat by field scouts in the past week. Severities generally ranged from 1-15% of the leaf area with symptoms. Trace levels of Septoria infections also were observed in a few fields in the NE and spot blotch was observed in a few fields in the SW.
Wheat leaf rust was found in spring wheat in southeast and east central counties, but also was observed in Rolette County in the north and in winter wheat north of Devils Lake. Severities were only at trace levels. The USDA Cereal Disease Lab reported severe leaf rust in winter wheat in Kansas in their latest Cereal Rust Bulletin.
In barley, both net blotch and spot blotch fungal leaf spots have been observed in young crops. Recent rains across many areas have favored these fungal diseases.
A reminder: weekly observations of diseases and insects by NDSU IPM field scouts are available at the NDSU IPM web site:
Extension Plant Pathologist
SCLEROTINIA RISK MAP FOR CANOLA
The Sclerotinia risk map forecasting system for canola is available again this year. Maps can be accessed through the NDSU NDAWN website or through the Northern Canola Growers Website. The forecasting system is based on soil moisture as it is required for the apothecia (small mushroom structures) to grow from the sclerotia in the soil. The apothecia produce the spores that infect canola petals. It is important to know the growth stage of the canola fields when checking the risk map. Canola is only susceptible to Sclerotinia infection when it is flowering. The NDSU NDAWN website is:
The Northern Canola Growers website is:
Extension Plant Pathologist