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Corn+Soybean Digest

Brazil Copes With Rust

The wave of worry over Asian soybean rust continues to swell here in the U.S. Even with the flood of information being provided, American farmers just don't have hard-core experience fighting this newcomer soybean disease.

That's not the case, of course, with farmers from Brazil. They've battled the deadly disease since 2001.

At the end of January, Chris Ward, a farmer from Rondonopolis in the state of Mato Grosso, was just finishing his second fungicide spraying to fight rust. Each spraying runs him about $22/acre.

“It needs humidity and heat and usually shows up sometimes before the R1 stage,” he says. “When we see it, we spray immediately. If we find one leaf in a million, we spray. We use a preventative right away because if we use a curative, it means we've already lost yield.”

Ward, who grows 1,000 acres of 15-in. row soybeans in west central Brazil, plants buffer (sentinel) crops about 10 days earlier than his regular beans. If rust hits the early beans, he's ready to start spraying everything.

“After our first spray we wait 25-30 days and spray again. Generally, we think our early maturity beans have less problems with rust,” Ward says.

When spraying, he uses 4-6 gal./ acre and sprays small droplets at 70-80 psi. “We try to spray when the temperature is under 80ÞF. That means we're usually done by 10 a.m.,” he says. “Airplanes aren't as good as ground equipment for us. You need high volume and aircraft don't work that well.”

His advice to U.S. farmers? “Be sure you have fungicide available and in the shed. All other diseases, like stem canker and SCN, are a picnic compared to rust,” he says. “With rust you'll lose 100% of your crop.”

Fortunately, though, Ward doesn't think soybean rust spores are overwintering all that well during their hot, dry summer months.

Finding a rust resistant variety is a top priority for researchers in Brazil. According to plant breeder Claudio Takeda from Fundacao MT, they're 8-10 years away from developing a resistant variety. “If I was optimistic, I'd say only five more years. However, we had a rust resistant variety and it was obsolete in less than six months,” she says.

“We do have some resistant varieties, but they have other disease problems that make them ineffective,” Takeda says.

Rust hit the Paulino and Osorio Straliotto farm for the first time last year. With 4,000 acres of soybeans, they were downright scared. On a scale of 1 to 10, with 10 being the worst-case scenario, Paulino says they're at 10.

“We had a dry year last year so we didn't lose much,” he says. “But we're very worried about it and now plant test plots to spot rust early.”

The Straliottos also grow 1,500 acres of cotton, 500 acres of corn and 2,500 acres of grass for cattle near Sidrolandia in the state of Mato Grosso Do Sul, south of Mato Grosso.

Fernando Freitas grows 700 acres of soybeans near Santa Terezinha de Itaipu, 18 miles from Foz do Iguacu City in the state of Paraná. Last year, rust started to show up on a few farms in his area.

“We didn't have much of a problem because we don't get the rainfall like they do to the north in Mato Grosso,” he says. “We're just not very worried about it this year.”

In fact, Freitas says they're not even spraying for rust this year. However, if he gets a week of solid rain, he might reconsider.

The company that sells Freitas inputs, like seed and fertilizers, scouts his beans as part of its service and he relies entirely on them for advice on spraying for rust.

Domingos Rodriges grows about 3,300 acres of beans and doesn't worry much about rust, either.

“We sprayed for rust with a preventative after bloom, but only one spraying,” he says. “Some in the area are spraying two times at a cost of about $20-25/acre.

“I am worried that rust could show up more on our higher areas where there's more wind to move the spores,” he says.

And Zanoni Buzzi, who manages the Toledo branch of COAMO, one of the largest cooperatives in Brazil, says rust just hasn't been a problem for their member farmers. Mostly, he says, that's because they spray a preventative fungicide twice a year.

Toledo is located in the southern state of Paraná where farm sizes are much smaller, averaging about 120 acres each.

Brazil farmers have had three years to adjust to their battle against rust. U.S. farmers, on the other hand, are just beginning their vigil.

“Brazil farmers watch for it (rust) and are willing to spray,” says David Gillen, White Lake, SD, a farmer who recently traveled to Brazil.

“They're not worried about huge yield losses, just extra production costs,” he says. “It's almost like they've accepted it and are now waiting for resistant varieties.”

Gillen isn't all that worried about rust appearing on his south-central South Dakota operation this year. “We have low humidity, little rain in July and August, and we don't have a tight canopy on our beans,” he says. “Plus, I'm confident in the fungicides we'll have to put on.”

Raymond Repp from Perry, IA, part of a rust first responder team, just returned from his second trip to Brazil. This time, he was dead set on learning about rust.

“I think in areas where they're getting a lot of moisture, like Mato Grosso where it can rain every day, they just spray and don't worry about it,” he says.

Repp believes that in the more southern parts of Brazil farmers don't seem to be as concerned about rust because it's drier and temperatures are a little lower.

“I was a little surprised at how much preventative spraying they were doing without actually identifying it (rust),” he says. “Only one farmer we talked to didn't spray.”

Even before his recent trip to Brazil, Repp had decided to plant sentinel fields of beans on his farm this year to help identify the disease when it first shows up.

“I'm less concerned about it appearing in Iowa now than I was when it was discovered in Louisiana last year,” Repp says. “I've learned more since then. And like bean leaf beetles and aphids, we just have to scout and be ready.

“I'm going to have some fungicide on hand, enough to treat about 20% of my acres. After that, I'll just buy more. I am worried that some people will store fungicides and in a couple years we'll have a lot of old chemicals floating around,” Repp says.

Bill Chase from Wolsey, SD, is a little concerned about whether there will be enough fungicide available if rust finally reaches his east-central part of the state. “But my dealer says he'll be able to cover the seed acres he's sold me.

“I'm also a little worried about spraying in a timely manner. Brazil farmers put down a preventative and maybe that's what we'll do, too,” he says.

Chase sums up his concerns like this: “Farmers in Brazil aren't in a panic over rust and I don't think we should be either.”

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