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Heat makes forage treacherous; farmers working ‘early shift’

More than 95 percent of state under drought. In drought, johnsongrass accumulates deadly prussic acid, fatal to cattle. Client to Extension agent: “Things are looking up. We’re one day closer to the next big rain!”

Arkansas cattle producers are sweating over water supplies and the deadly heat-triggered treachery of johnsongrass, say Extension agents for the University of Arkansas Division of Agriculture.

Meanwhile, row crop producers are running irrigation and fending off overwhelming numbers of insect pests – especially bollworms.

According to the U.S. Drought Monitor map released on July 28, 95.57 percent of Arkansas is under some type of drought classification. The most severe drought is along the southernmost row of counties. While popup showers brought some local relief over the weekend, the forecast through Friday for most of Arkansas is dry with daytime highs exceeding 100 degrees.

“I talked to a cattle producer this morning with questions about johnsongrass,” said Berni Kurz, Washington County Extension Staff Chair. “He lost a cow over the weekend to prussic acid poisoning.”

During drought conditions, the normally harmless forage, johnsongrass, begins to accumulate prussic acid – also known as hydrogen cyanide.

“He said that he knew better but felt like he had no choice but to turn the cows into a field that had some johnsongrass patches,” Kurz said. “There’s not much pasture is left. Hay is being fed and some cattle producers have opted to disperse” cattle they can no longer feed.

Perilla mint, a square-stemmed, purple-leaved mint family member known as “rattlesnake weed,” is another danger. The mint contains a toxin that can induce respiratory failure in cattle.

“Although they dislike mint, when preferred forages aren’t available, grazing animals will eat it,” said Robert Seay, Benton County Extension Staff Chair.

In southern Arkansas, where drought has persisted longest, growers are switching tactics as even backup water sources disappear.

“The one thing I'm hearing more and more of in my county is scarcity of water for ponds, creeks, streams,” said Jaret Rushing, Calhoun County Extension agent. “Many folks don't have an alternative watering supply, except for their ponds, and with the lack of rain, many people are scared that their ponds will not suffice as a watering hole for their livestock.

“I've heard of several producers purchasing watering tubs this year, just to have a means for watering their cattle and horses. Many have never used these before.”

In western Arkansas, “I have a producer who is looking at creative food sources like cannery by-products for feeding his livestock to make up for high price of hay and poor quality of his pastures,” said Dustin Blakey, Sebastian County Extension Staff Chair.

However, the heat has benefited at least one grower.  “A large vegetable producer is drip-irrigating and the crops are coming off good,” Kurz said. “The dry conditions have saved him from having to apply fungicides weekly, but this cost saving has been put to irrigation needs.”

Kurz said the producer is beating the heat by harvesting at daybreak. It’s ditto in the Delta.

“Most everyone is doing the work early in the day so that in the afternoon they are inside,” said Robert Goodson, Phillips and Lee county Extension agent. “The main thing is being to stay out of the heat as much as possible.”

Division entomologists are reporting high numbers of bollworms in soybeans, with sampling at one field in northeastern Arkansas finding more than 10 times the recommended action levels. 

Fields at highest risk are those with soybean plants that are blooming or about to bloom, are beginning to set pods and have not achieved canopy closure.

Kurz said farm fields become attractive to hungry insects because it’s the only patch of green around. In the case of the vegetable grower, the insects are also carrying watermelon mosaic virus that’s settling on squash. 

However, if anyone needed evidence of the optimistic nature of farmers, Seay said he was told by one client: “Things are looking up. We’re one day closer to the next big rain!”

For more information on crop production, visit, or contact your county Extension office.

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