Small Grain Disease Risk: July 2, 2007 Update
 
Soils in many Valley field locations are dried down now.  Rain showers are localized and according to the model, are primarily in the Kittson, Roseau and Marshall Co. areas.  The risk of a Fusarium head blight epidemic is much lower in other locations.

Risk models from July 3, 2007

For current outlook: http://mawg.cropdisease.com  

FUSARIUM HEAD BLIGHT.  Today, Ardelle Knudsvig, Minnesota Department of Ag, identified FHB/scab symptoms from an early planted wheat field located west of Argyle.  Scab incidence and severity are low, however infected spikelets are showing a pink color as the fungus continues to grow while humidity is high.  
 
WHEAT LEAF RUST.  Ardelle Knudsvig also reports that rust is common and widespread in Kittson and Roseau Counties.  Fortunately, pustules are not common on flag leaves.  Many fields are at flowering, or beyond, so fungicide treatment over-and-above the application to manage FHB/scab is not advised for leaf rust control.
 
BACTERIAL STRIPE.  This bacterial disease is widespread and common.  This is the same disease that was at epidemic proportions in the Valley during 2005.  Pathogen spread and disease development are promoted by wet weather.  Flag leaves in some fields are severely injured.  There is no recommended treatment for bacterial stripe since fungicides don’t have any control activity on bacteria.

for more information on bacterial stripe from 2005

PURPLE LEAVES.  This symptom is common in wheat fields.  A sample of spring wheat from Lamberton was identified from lab tests as Aster yellows.  We will continue to test samples to determine whether the disease is Aster yellows (phytoplasma pathogen) or Barley yellow dwarf (viral pathogen). Symptoms are similar.

Dr. Charla Hollingsworth,
Univ. of Minnesota Extension