Head Scab Risk Update

Updated scab risk maps for non-irrigated spring wheat (susceptible varieties) and durum are provided below. According to the National model, there are variable levels of risk in Williams County. Those along the Divide County border may want to consider a fungicide application if their later planted crop is currently at flowering. The NDSU model is still predicting low risk in much of Williams County.




 
 
 
The maps above are for crops which are in the early flowering stage right now. That would likely be the late May planted crop. Most of the durum and spring wheat planted in our region is beyond the time point where a fungicide application for head scab would be effective.



Predicted growth stage based on the NDAWN Growing Degree Day (GDD) model for Williston. Rainfall is based on the Williston NDAWN station.

Dr. Jochum Wiersma, Small Grains Specialist with the University of Minnesota stated the following when interpreting the current risk model, “As a consequence of the hit-and-miss nature of these rain events, both the NDAWN disease forecasting and the national risk model might be overestimating the risk for some of your fields if last week's rains kept missing your fields and fields are much drier.” As I have said in previous issues the converse is also true. If you are in a “low risk” area but your fields have been getting rains your neighbor missed take that into consideration. These risk maps are useful resources but as we know from experience they are not foolproof.

When your crop is nearing that soft dough stage and you see white heads in your fields it may or may not be head scab. We know that wheat stem maggot and root rot can also cause premature bleaching of plants and/or heads. When diagnosing head scab I look for partially bleached heads and the pinkish fungal growth associated with the Fusarium pathogen. When the symptoms are at the bottom of the head the stem will also be dark brown to black. You can dissect the head and see if the seed is white and shriveled. We only get one chance a year to make management decisions and evaluate the outcome so it can be helpful to go out and see if any scab is present.


Symptoms of head scab (Fusarium head blight) on durum
 
 
 
If you have any questions about head scab management or diagnosis please feel free to reach out.
 
 
Dr. Audrey Kalil
Agronomist/Outreach Coordinator
 
 
 
 

White Mold in Soybean and Dry Bean

White mold, also known as Sclerotinia stem rot, is favored by wet soils and mild air temps. Soybean and dry bean become susceptible to this disease during flowering and that is when we want to apply a fungicide for the control of white mold. For more details on fungicide timing and application review our last newsletter issue.

With the change in the weather this week from hot and dry to cool and wet irrigated dry bean and soybean producers should evaluate their white mold risk. If air temps continue to be moderate, the risk for infection and disease development will be higher.
 
There are several fungicides that are effective for white mold control, so reach out to our agronomy team if you have any questions on fungicide selection and rates.

Scouting for white mold typically happens as the crop is nearing maturity, but is still green. Open up the canopy and check the stems and lower pods for bleaching and small black pebble-like sclerotia. Fields with a history of white mold will be higher risk in the future, so it is important to document when this disease occurs even if it is not at levels causing yield loss.




 
 
 
Dr. Audrey Kalil
 
Agronomist/Outreach Coordinator
 
 
 

On the Horizon Podcast - Season 2, Episode 38: Mid-Season Agronomy Check In

 

Dr. Audrey Kalil joins Levi Hall for an agronomy update across western ND and eastern MT. From peas and lentils to wheat and irrigated corn, get real-time insights on crop conditions, weed pressure, and the impact of recent weather. Plus, hear about Horizon’s 0% fungicide program and key takeaways from the MSU Sidney field day. Listen to the podcast on our YouTube Channel, or podcast streaming app.

 

Weather Update