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Disease pressure can impact farmers across Wyoming in spring months

by Wyoming Livestock Roundup

Worland – Farmers across Wyoming are faced with a myriad of challenges each year, ranging from weather and fertility issues to weed and pest concerns. 

Jeremiah Vardiman, University of Wyoming (UW) Extension educator in Park County, said fungal infections can put pressure on crop producers across the state and encouraged producers to pay attention to the potential for challenges


“Ergot is a fungal infection in malt barley in the Big Horn Basin,” Vardiman said. “If the amount of ergot hits above a threshold level, the barley will be rejected when we try to sell it. There is also a threshold of how much we can feed to livestock.”

Ergot can also be found in bromegrass, ryegrass and a wide range of other hosts, meaning it is endemic in the environment. 

“We have ergot here, and we can see it on rangelands,” he explained. “Rangeland plants keep the fungus alive, and when we have the right conditions, it explodes in our croplands.” 

In 2018, ergot was seen across the basin, impacting barley and wild rye seed production. 

Inside the fungus

Because ergot is a fungus, it is mainly dependent on weather, and it often establishes during cool, wet springs. 

“When the grass goes to flower, fungus spores land in the flowering head. At that point, the head gets wet, and fungus takes hold,” Vardiman said. 

To help prevent ergot, he noted farmers should not irrigate as the barley or grass starts to flower in the spring.  

“We strive for uniformity in our crop fields, and if we can keep our fields uniform, we won’t have pockets of ergot,” he added.

Managing ergot

If ergot is found in a field, Vardiman said producers should bury crop residue or burn it to try to eliminate the fungus. 

Vardiman also mentioned if producers want to try to harvest a field ergot in it, they should harvest their clean fields first. 

“We don’t want to harvest ergot and spread it through the rest of our farms,” he said. “If we do harvest ergot fields, clean the combine.”

Feeding livestock

Feeding grains with ergot can cause problems in livestock, so Vardiman cautioned against feeding ergot-infested grain. 

“The alkaloids from the ergot build up in the body of the livestock and cause vasoconstriction,” he explained. “We see vasoconstriction in the tips of the ears and tails first, but when it is severe enough, we also see vasoconstriction in the lower extremities.” 

Vardiman continued, “Vasoconstriction means the blood vessels are constricted and blood flow stops.”

In severe situations, the hooves can fall off as a result of lost blood flow to the feet. In addition, cattle can develop rough hair and lose weight. 

While ergot is endemic across the state, Vardiman added the appearance of ergot in rangeland conditions is minimal and is unlikely to cause a problem with livestock. 

Fusarium head blight

Another disease concern for grains is fusarium head blight, also called DON. 

“DON affects the seed head of barley,” explained Vardiman. “It is also a fungal disease, and there are Food and Drug Administration limits on the level of DON we can have in our crops.” 

Fusarium head blight discolors seed heads. Affected grains are also shriveled and wrinkled. 

“We haven’t been able to breed a fusarium resistant variety of barley,” he said.

Most frequently, fusarium head blight is associated with irrigation or rain during the heading period of barley. 

“Cool, wet spring weather favors this infection,” Vardiman said. “Many producers in Montana see problems with DON.” 

He further notes minimum and no-till farming practices seem to correlate with higher levels of fusarium head blight. The worst cases are seen in minimum or no-till fields where barley is planted after a corn crop. 

“In this case, there is a green bridge. The corn is the host, and it is passed on to the barley,” Vardiman said. “Managing our crop residue and utilizing crop rotations that break the cycle from grass-to-grass crops are important to reducing DON.”

Managing fungus

 If producers find ergot or fusarium head blight, Vardiman said fungicides are not an excellent option for control.

“Fungicides provide very little above just suppression,” he explained. “They suppress the spread of the fungus to healthy plants, but they do not kill the fungus.”

Spraying fungicides early before it is found can be useful as in preventing fungal challenges, but Vardiman noted, “We can’t wait to spray a fungicide until after we find ergot or fusarium head blight.”

Weather impact

Because disease pressures often result following a cool, wet spring weather, Vardiman encouraged farmers to watch weather patterns when assessing the risk of fungal diseases in particular.

“Our forecast shows a 40 to 50 percent chance of above normal temperatures for the Big Horn Basin this spring,” said Vardiman. “As for precipitation, we should see near normal precipitation.” 

“It looks like we can expect warmer, maybe drier weather,” he added, “so we might have fewer disease challenges this year. But, with the weather, we can never be sure what we’re going to get.” 

Saige Albert is managing editor of the Wyoming Livestock Roundup. Send comments on this article to

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