As row crops go in across the state, dont forget about those small grains! Early season wheat diseases may be encroaching on your farm and diligent scouting is key to a healthy stand. Before making any fungicide applications, spend time in your field determining what disease(s) may be present and at what incidence rate. The following information is summarized from an article written by our SDSU Extension Plant Pathology Field Specialist Connie Strunk and our State Plant Pathology Specialist Madalyn Shires.
Septoria is a common early season wheat disease found in South Dakota, and many areas have experienced conditions favorable for its growth. This fungal pathogen, Zymoseptoria tritici has favorable development in cool, wet weather. Elliptical, tan-brown lesions with a yellow halo will develop on leaves; typically, the center of the lesion dies, and pycnidia (a ball-shaped, gelatinous, gray-brown area) becomes visible in the center of the lesion, making it appear speckled. If you spot this disease at threshold levels, there are several commercial fungicides available for protective treatment one or more times (if needed). See the South Dakota Wheat Pest Management Guide for a full list (and summary) of available pesticide products.
Tan spot is another common early season wheat disease found in South Dakota and surrounding areas. This fungal pathogen, Pyrenophora tritici repentis survives on wheat stubble and can lead to poor tillering and yield reduction. These lesions appear on the lower leaves of the plant first, and eventually can be found in the mid canopy and throughout the rest of the plant. Tan spot lesions are dark brown and surrounded by a yellow halo. The lesions often coalesce (grow together), which leads to premature dying of infected leaves. If tan spot is an issue on your farm, there are many products available for protection from this fungal disease. Consult the South Dakota Wheat Pest Management Guide for more information. Printed copies of the guide can be found online at extension.sdstate.edu (search Pest Management Guide), or in print at an SDSU Regional Extension Center nearest you.
Small-grain diseases are tough to scout and spot in a timely manner. Often, preventative fungicides are an effective management strategy to avoid yield loss. Check out the SDSU Small Grains Disease Prediction Tool to keep track of weather conditions that may be ideal for leaf spot and Fusarium head blight (or scab). Visit https://climate.sdstate.edu/tools/smallgrains/ and select the growth stage and weather station closest to you. This tool assists with the prediction of disease development (leaf spots and leaf rusts) based upon weather conditions. It is designed to aid producers in making the decision to apply fungicides or not (Fusarium predictions begin when wheat is heading).
To find out more information on wheat and other small grain diseases, visit extension.sdstate.edu and select your crop of choice under the crops tab. In addition, you may sign up for our weekly Pest and Crop Newsletter that is emailed out during the growing season with timely information for growers and consultants visit https://extension.sdstate.edu/about/newsletters to sign up. As the growing season moves forward, keep in mind that sudden changes in weather can alter disease prediction and patterns, making scouting and prediction tools highly valuable for the prevention of yield loss due to plant disease.
Upcoming SDSU Extension agronomy events
Sign up and find out more details at extension.sdstate.edu/events:
- May 28 Garden Hour; join this free webinar for an hour of garden-related Q&A
- June 21 Ag Economic Dialogues; join this free webinar designed to help farmers and ranchers make profitable decisions for their operations.
- June 27 Dakota Lakes Research Farm Summer Field Day at Pierre; come visit DLRF and learn what research is happening!
- July 9 Southeast Research Farm Summer Field Day at Beresford; come visit the SERF and learn what researchers are working on this year.
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