Wheat is growing rapidly in the RRV. Before you know it, awns will be emerging and a decision will need to be made about applying an early flowering fungicide. The on again-off again wet and humid weather conditions will increase the risk of a scab epidemic if the trend continues until the crop is flowering.

How does one decide if an early flowering fungicide application is needed? Start by answering the following questions.

• What crop residue or stubble was the wheat planted into?
• What variety was planted?
• When will the crop be in the early flowering growth stage?

SCAB EPIDEMIC RISK FORECASTS.
With the answers to these questions, access the Minnesota Scab Epidemic Risk Forecasting website at http://mawg.cropdisease.com. A colored-coded state map will be displayed that shows statewide FHB epidemic risk level differences at a glance (Figure A). Dark green coloring indicates low risk, yellow indicates moderate risk, and dark red indicates high risk that a scab epidemic could occur.

PLANT PATHOLOGIST COMMENTARY.
This is a new upgrade to the site and is meant to help with map interpretation by adding on-the-ground information and a plant pathologist’s perspective. Found just below the colored map of Minnesota (Figure B), commentary will contain reported and observed disease information and additional tidbits to consider when making the decision to manage disease. The text will be updated periodically.

GLENN ≠ OXEN.
To obtain a specific risk figure for a variety, click on the state map at the approximate site where the field of interest is located and select a flowering date. This estimate is based on actual, observed weather conditions, so a date into the future is not available. However, users can use past and current dates in succession to determine if the risk level in the area is increasing or decreasing as the flowering date approaches. Again select an approximate location of the field by clicking on secondary, zoomed-in map. A window with a drop-down menu will appear where you can select your variety, or its FHB resistance level, for an approximated percent risk of disease (Figure C). Risk of an epidemic is substantially reduced with varieties such as Alsen or Glenn compared with susceptible varieties such as Oxen or Reeder.

GROWTH STAGE ESTIMATOR.
To estimate the growth progress of your crop, select the “Wheat Growth Model” and a different state map will be displayed. Click on an approximated location for the field of interest and type in the needed information (variety, date planted, seeding depth), then select the “GO” button. An estimate of the crop growth stages will be displayed. This estimate is based on growing degree days for wheat and is calculated using observed weather conditions. As the number of weather data increase, the estimate will be more and more accurate. For example, an estimate of the early flowering date made at the 2-leaf stage is less accurate than when it is made at the sixth leaf stage. This estimator has proven to be reliably accurate.

ADDITIONAL FEATURES include leaf disease severity estimators for tan spot, Septoria, and leaf rust. WEATHER CONDITIONS can also be accessed from the left side of the home page.

Charla Hollingsworth
UM Extension Plant Pathologist