Potential Winter Wheat Diseases

Jesse Fulbright, MSU Liberty County Extension

With much of the snow having melted or melting out of the fields I wanted to turn people’s attention to the thought of potential diseases in our winter wheat due to the excessive snow cover.  Much of this information comes from Mary Burrows, Extension plant pathologist and a Montana Ag Alert that she put out to statewide producers last week.

First, let’s talk about snow mold.  Snow mold occurs on fall-planted crops under prolonged snow cover or wet conditions with freezing temperatures.  If you see patches of fields with dead plants, look towards the edge of the patches at the sick plants.  If you see lesions on leaves with a tan center and brown halo, this is likely pink snow mold, which is the most common snow mold we see here in Montana.  The good news is that this disease will not infect the spring crop, it requires extended low temperatures and moisture.  It is favored by cool wet falls and continuous winter wheat planting.  There may be a difference in varieties. There is another snow mold commonly referred to as ‘speckled’ snow mold.  Dead plants won’t recover, but if the plants are tillering and have a good root system they should pull out of it.  There is no risk of the fungus spreading to a spring crop should you seed spring wheat nearby.  If replanting, please use good management practices to prevent Rhizoctonia root rot if soil conditions continue to be cool and wet.

Snow mold patches on winter wheat caused by Microdochium nivale and
Myriosclerotinia borealis (Photo courtesy of apsnet.org)

 Rhizoctonia root rot (bare patch) can be partially controlled by seed treatment and by crop rotation, good weed control, and eliminating the ‘green bridge.’  This is a ubiquitous fungus in the soil with a broad host range that prefers cool, wet springs.  Usually you won’t see complete devastation in a field, but if you’ve ever had very shallow-rooted plants and uneven height in the field, likely Rhizoctonia was involved.  Use a good seed treatment with efficacy against Rhizoctonia if you suspect you may have had a problem in the past.

The Long and the Short of Your Lawn Height During the Winter

Jesse Fulbright, MSU Liberty County Extension

This summer my oldest son took over mowing the lawn at home.  This was a welcome relief as my summers can get quite hectic and sometimes it goes long periods of time before I find the time to mow it myself.  It also allowed me to tackle other things around the yard that I don’t often get to.  However, it’s now getting close to time to putting our yard to bed for the winter.

That lends itself to the question, should a person mow their grass shorter before winter?  The answer is, it depends.  Let me elaborate and we’ll see if I can clear things up a bit.  So, right off, you should be mowing your grass during the growing season at two to two and a half inches.  That allows the grass to produce enough leaf surface for survival.  For winter though and how tall to leave the grass we need to consider how much snow we get and how long it sticks around.  As this often differs winter to winter, I don’t know if we can give a concrete answer.  However, what is known is that snow mold, which is a fungal disease of turfgrass in Montana, is prevalent in areas that have a lot of snow and where it sticks around for a long time.  Snow molds can be gray or pink and they love cool, wet environments.  Ultimately, snow molds cause poor green-up in the spring and areas that look matted down, often with a growth of mold.  The area can enlarge in the spring if the temperatures remain cool and there is timely rainfall.  Once it does warm up in the spring, the mold goes away, and the grass quite often recovers. 

If the grass is cut tall before winter, it creates an even better environment for the fungus to grow.  So, if you hedge your bets and count on more snow cover this winter, with it lasting more than 60 days, mow the grass short, approximately an inch to an inch and a half high.  However, if you figure on an open winter with not much snow cover, keep the grass tall, at approximately three inches.  That way, the grass will insulate the crown of the grass roots and keep them from getting too much frost winterkill over the winter months. 

If you have further questions regarding fall lawn care I would encourage you to contact your local county Extension office.