CHALLENGES FOR WHEAT PRODUCERS

This year has been a challenging year for wheat producers in Ohio. Diseases like Stagonospora and Fusarium head blight (Head Scab) have plagued some wheat fields. Concerns this harvest season have focused on head scab and toxins the fungi can produce. Head scab is a condition caused by several Fusarium species of fungi. The same species can infect both corn and wheat along with other grass species like rye and barley. In corn the disease is called Giberella ear rot (named for the reproductive phase of the Fusarium fungi). Many producers are asking why head scab was so prevalent this year. A combination of disease activity in corn and wheat last year and warm, wet conditions during wheat flowering this spring allowed the disease to spread.

The fungi over-winter on corn, wheat, and some grass weed residues becoming active again in the spring. In wet warm springs the fungi grow rapidly producing spores which are transferred by wind. These spores land on wheat during flowering stages and cause infection. Once growing in wheat the fungi produce a toxin commonly referred to as “vomitoxin”. This toxin when consumed at certain concentrations (measured in parts per million or ppm) by livestock produces an unwanted side effect described by the name. There is no risk of death from the toxin in adult livestock, however the toxin will make animals sick and reduce feeding. With breeding aged animals there is a risk of fetal death. This makes those animals, especially swine the most susceptible.

Infected grain and grain by-products can be fed as long as they are fed within established limits for livestock. For beef cattle over 4 months in age, horses, and chickens the limit is 10 ppm as long as the wheat consists of no more than 50% of their diet. For dairy cattle and swine the limit is 5 ppm where the grain does not consist of more than 20% of their diet. The majority of the toxin is present in the grain and chaff of the plant; however it can be present on the wheat straw. Straw for feeding and bedding should be tested to make sure vomitoxin levels are safe for livestock. The toxin cannot be absorbed through the skin but animals will chew on straw bedding so there is a chance of ingesting the toxin.

Humans are susceptible to vomitoxin so it is important to take precaution when working with grain and straw. The toxin will travel on dust and can be inhaled and ingested. Most of the harvest is over but for reference combines with a closed cab and air conditioning will generally filter the air to safe levels. Just remember A/C systems have a tendency to cut out on the hottest, longest day of the harvest. So if the cab door is open it’s a good idea to wear a dust mask and eye protection. Post harvest, anyone handling the grain or on a bale wagon should wear a dust mask and gloves unless the mask interferes with breathing. With temperatures in the 90s this week and the risk of exposure it’s a good week to bale with a tractor with a cab and A/C. Remember to wash your hands before eating, drinking, smoking, chewing gum and tobacco, or using the restroom.

Recommendations for this fall and next season revolve around breaking the disease cycle. Dr. Pierce Paul, Plant Pathologist for The Ohio State University, is recommending deep tillage this fall to bury wheat residue and speed the decomposition process. Applying fungicides or other chemicals to wheat straw is not supported by research on reducing wheat straw or disease infestation so be careful of cure-alls. Wheat going into the ground this fall should be certified seed since planting with infested seed can continue the pest cycle. Next season scouting wheat fields is recommended especially if we have warm wet conditions. Remember don’t just apply a fungicide, proper timing of application and infection levels of the fungi will determine if the application is warranted and will be profitable.

If you have any questions or concerns about head scab, vomitoxin, or other related agriculture or natural resources topics, contact Justin Petrosino at Ohio State University Extension, Darke County, at 937-548-5215. Please review the CORN newsletter at http://corn.osu.edu/ for updates on head scab and other crops news.