Scab Epidemic Risk Model
Legend:
Plant Pathologist Commentary: Updated July 2, 2009. Spring wheat canopies are thick and lush in many RRV locations. Minnesota Dept. of Ag (MDA) Plant Pest surveyor Ardell Knudsvig is reporting few disease or insect issues in NW Minnesota.
According to Knudsvig, while aphids and grasshoppers are present, their populations are low. Moreover, tan spot diseased fields are not common unless the crop was planted into wheat residue. In these cases, tan spot is severe on susceptible varieties if fields were not treated with a fungicide. Without exception, fields that he surveyed this week show that producers have leaf disease issues well under control.
On June 19, wheat leaf rust was detected in Douglas Co. by Roy Mayeda also with the MDA Plant Pest Survey. He noted a single pustule on one leaf of the 30 winter plants that he sampled. The disease was at a trace level at that time. More recently, U of M Extension Educator Doug Holen received winter wheat plants that were severely diseased with leaf rust. Plants were from a field near the town of Nicollet in Nicollet County. Spring wheat’s growth stage is lagging behind normal, so leaf rust establishment in Minnesota needs to be monitored closely.
Crop growth stages are advancing toward flowering. Please stay informed as to the risk for scab in your crop. The disease has caused production issues to our south in the winter wheat crop. With the extended periods of soil saturation and abundance of corn residue in our system, the forecasting system may underestimate our risk for Fusarium head blight (FHB, scab). If your crop is worth protecting, this may be a good year to consider applying a fungicide.
Important Note: Please review
Terms
of Use before utilizing this site. This Fusarium Head Blight (FHB, or
'scab') model is a pre-flowering model. It is meant to be applied using weather
conditions during the week leading up to flowering. Therefore, the epidemic
risk for a particular field should be determined by selecting a time coinciding
with or just prior to the initiation of flowering in that field. A growth stage
estimator is available on this website, but you should still monitor growth in
your own fields to better estimate the date on which flowering begins.
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