Growers, weather stopped early soybean rust outbreak

Growers, weather stopped early soybean rust outbreak

• Rust was detected along a southern tier of North Carolina counties on Sept.12, but Mother Nature, a well-coordinated system of sentinel plots, and timely actions by growers stopped rust in its tracks.

Soybeans and wheat made an awesome economic combination for growers in the Southeast this past growing season, creating plenty of optimism for profits from this year’s beans and optimism for planting more of the crop in 2013.

Even the earliest appearance on record of Asian Soybean Rust did little to slow down what is shaping up to be one of the best soybean crops on record in some parts of the Upper Southeast.

Rust was detected along a southern tier of North Carolina counties on Sept.12, but Mother Nature, a well-coordinated system of sentinel plots, and timely actions by growers stopped rust in its tracks.

Though the disease was documented on Sept. 12, in North Carolina, the earliest on record by three days, it appears there was little damage to the state’s 1.65 million acre soybean crop.

Duplin County, N.C., Extension Agent Curtis Fountain says once the disease was detected in counties less than 100 miles from his area, growers quickly reacted and applied fungicides when needed.

Fountain says, “Remember the disease triangle/pyramid (host, pathogen, and favorable environment). All 3 are needed for disease development and spread. In other words, host + pathogen + favorable environment = disease. Obviously time is required as well.

North Carolina State University Plant Pathologist Steve Koenning and Soybean Specialist Jim Dunphy issued timely updates on movement of the disease and provided virtually day-to-day observations on when and what to spray to best manage ASR.

Koenning says soybeans that have just reached full bloom (stage R2) typically have 65 days until they’re safe from rust or frost (stage R7), if they are full-season soybean, or closer to 55 days if they are double-crop soybeans.

If soybean plants have small pods in the top, (stage R3), they have 55 and 47 days, respectively, to R7. With full sized pods in the top of the plants (stage R4), they have 45 and 38 days, respectively, until R7.

From stage R5 (small seeds in the top of the plant) they typically have 35 and 30 days, respectively. From stage R6 (full sized seeds in the top of the plants), they typically have 20 and 17 days, respectively.

Needed help from Mother Nature

With ASR making a record early arrival, growers needed some help from Mother Nature to manage the potentially yield destructive diseases. They got it!

Fountain says the average daily air temperature for the previous four years for the time period when soybeans would have been at risk in Kenansville, N.C., is 66 degrees F and the first frost date is from Oct. 21-31.

During that time frame, when soybeans were at risk, conditions were ideal for soybeans to finish their productive stages, but not good for rust development.

Like most areas of North Carolina and Virginia, the North Carolina Extension ag agent says most growers in Duplin County didn’t see a risk from ASR, and, therefore, didn’t spray soybeans for that disease alone.

Koenning adds that North Carolina State Extension doesn’t recommend spraying soybeans with a fungicide to control ASR if soybeans are not yet blooming, if they are blooming, but rust has not been confirmed within 100 miles, or if full sized seeds are present in the top of the plant (stage R6).

Such pre-bloom applications have seldom improved yields, and repeated applications will likely be needed to provide season-long protection against rust.

The higher labeled rates tend to provide more days of prevention, and may thus require fewer applications.

The triazole fungicides, alone or in combination with a strobilurin fungicide, will probably provide better prevention of rust than a strobilurin alone, he adds.

Other parts of the Southeast have had more of a battle with Asian Soybean Rust.

By the end of October virtually every county in Alabama and Mississippi had documented cases of rust. In Louisiana and South Carolina about half the counties were infected with the disease.

Little rust was reported in Tennessee, Kentucky and Virginia and appeared to be no threat prior to the first frost in these states.

In South Carolina, Extension Corn and Soybean Specialist David Gunter says this year’s soybean crop went through some stress early in the season from drought, but late season rains helped growers produce what appears to be one of the best soybean crops on record.

“We had some issues with kudzu bugs, but not as severe as we thought they might be.

“Overall, if we can finish this crop out, it will almost certainly be the best soybean crop I’ve seen since I’ve been working with the crop,” Gunter says.

High expectations for 2013 crop

Optimism for this year’s crop may only be topped by high expectations for the 2013 soybean crop.

This year, growers in the Carolinas and Virginia will likely harvest about 2.5 million acres of beans. North Carolina will harvest more than half that total, or about 1.5 million acres. Virginia will likely harvest about 560,000 acres and South Carolina about 375,000 acres.

One reason for optimism is the increase in wheat acreage expected in the region for the 2012-2013 crop.

Last spring and summer, growers in the Upper Southeast harvested about 1.4 million acres of wheat. This year expectations are for an estimated jump of 10-20 percent in wheat acreage, or a bump as high as a quarter million more acres.

The increase in wheat acreage is typically an indicator of soybean acreage, because a high percentage of beans in the tri-state area is planted behind winter wheat.

In several cases in 2012, double-crop beans, because of better summer and fall weather, will likely out-yield earlier planted conventional beans.

Over the past few years, better varieties and better technology have significantly reduced the yield drag between conventional and double crop beans.

Nationwide, projections seem to bear out optimism for increased wheat-soybean acreage in 2013.

University of Illinois Agriculture Economist Gary Schnitkey says, “Operator and farmland returns in 2013 are projected at $314 for soybeans, $152 for wheat, and $204 for double-crop soybeans.

“Wheat-double-crop-soybeans together have a combined return of $356 per acre ($356 = $152 return for wheat + $204 return for double-crop soybeans).”

In the Midwest, corn is still king, bringing in an estimated $467 per acre, but in the Southeast dryland corn will be hard-pressed to compete with the income generated by wheat and soybean double-crop.

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