Rust never sleeps

Soybean fungus threatens yields and fields.

Frank Jossi | Contributing Writer

Published May 1, 2005  | May 2005 issue

There's a potential crop killer in the air, and it's got soybean farmers across the country running scared. Matt Mechtel thinks he might run, too—all the way to the bank.

Asian soybean rust (ASR) has been widely publicized as this summer's potential blockbuster crop disease, threatening to lay waste to yields and fields from Texas to North Dakota in its flight from South America. But for Mechtel, president of the North Dakota Soybean Growers Association, the concept of a down year for his southern neighbors could mean a bumper year for his 5,000-acre spread 45 miles north of Fargo.

"I'm not real worried about it this year since they only found a small amount of it in the South late last year," Mechtel said. "It would take a catastrophic outbreak this year and the right weather for (soybean) rust to make it this far ... and with all the talk of soybean rust there'll be reduced acreage in soybeans and opportunities to make some money on soybeans. Some people's problems always present opportunities for others."

His optimism is not entirely shared by others in the region, among them the government official in his state charged with overseeing a response to the deadly disease. "[ASR] is a concern here; it's a concern everywhere," said Roger Johnson, agricultural commissioner of North Dakota, the Ninth District's second-largest producer. "It could have a catastrophic economic impact if it's not dealt with."

For now it appears federal and state government and industry officials are getting the word out on ASR in the Midwest and the South, the nation's two major soybean-growing regions. ASR has spawned many a Web site, news story and conference devoted to preparing for it and managing its spread. For now, at least, the chance for an agricultural tsunami seems unlikely since farmers should be aware of the danger ASR poses and what they may need to do about it.

The tale of ASR is one of an old disease finding a new home in the Western Hemisphere and—amid much uncertainty—a growing, coordinated local and national response to it.

Blowin' in the wind

ASR arrived in the United States late last year in Louisiana and later in eight other states, the most northerly being Tennessee and Missouri. A prevailing theory is rust spores caught winds during the autumnal hurricane season last year and landed first in the Gulf states. Luckily, a cool spell followed that likely destroyed most of the spores carrying the ASR, although in late February Florida state officials announced the disease had been discovered on kudzu in Pasco County. It is anyone's guess whether a strong current of southerly winds could blow ASR up again from South America or elsewhere this summer.

Before arriving in the United States, the pathogen's Western Hemisphere debut came in 2001 in Brazil, the world's second-leading soybean producer after the United States. Previously, the disease has made periodic appearances since first being discovered in Japan in 1903 and spreading from there to Asia, Australia, India and Africa. The pathogen mainly lays waste to soybeans but also affects 95 plant species such as beans, peas and kudzu, the last of which is a nonnative, anti-erosion weed of dubious value imported to Southern states from Asia in the 1930s.

The disease's tendency for methodical migration via wind patterns means rust spores will arrive first in states south of the Ninth District before descending on the region, if it does at all. Midwestern summers offer precisely the right conditions—high humidity, warm days—for the disease to flourish. After arriving the disease spreads rapidly when accompanied by moderate temperatures of 60 to 80 degrees and wet leaf periods of at least eight hours daily—in other words, a typical July week in much of the Midwest.

Concern over ASR remains high since the United States and the Ninth District, in particular, are no small players in the world of soybeans. The United States harvests more than 73 million acres of cropland worth $18 billion annually, according to the Economic Research Service, a research arm of the U.S. Department of Agriculture. Last year Minnesota ranked fourth in the country in soybean production (236 million bushels), followed by South Dakota (eighth place, 140 million bushels), North Dakota (11th place, 82 million bushels) and Wisconsin (14th place, 52 million bushels). Soybeans represent one of the top four cash crops in each of the four states.

Since the disease is new to the Western Hemisphere, the data remain slim on its impact. After an unusually wet season a few years ago, Brazil saw a loss of 3.4 million tons of soybeans, or 6 percent of the country's total production, according to the USDA. What might happen in the United States remains to be seen, but the USDA suggests soybean producers could suffer a hit of between $640 million and $1.3 billion in the first year alone. (The USDA did not divulge price or yield expectations used to estimate total economic losses. But roughly calculated, at $6 a bushel, this would break down to between 3.2 million and 6.5 million tons.) Subsequent years could bring losses of $240 million to $2 billion, the USDA predicts.

ASR works like many plant diseases. Once on a leaf, it shuts down a plant's ability to convert light energy to stored energy, commonly known as photosynthesis, said Geir Friisoe, manager of plant protection programs with the Minnesota Department of Agriculture. By preventing photosynthesis and diverting water and nutrients from the plant, ASR stops growth and can reduce yields by 70 percent if untreated, he said. An infected plant, undetected, can quickly create wind-borne spores capable of decimating soybean crops in surrounding fields.

Identifying ASR can be challenging. Jim Kurle, a soybean pathologist at the University of Minnesota, said ASR initially appears as a series of black spots on the underside of the low and mid canopy of soybean plants. When the spots appear the leaves become translucent. As the pathogen progresses the spots become orange and brick red—thus, the descriptor "rust"—and the disease moves up the canopy as it weaves a trail of destruction, according to Kurle.

At least the Midwest has an agent of resistance unavailable in other parts of the world: frigid weather. Soybean rust cannot "overwinter"—or survive—a Midwest winter, said Friisoe. Should the disease show up in Minnesota this year, it would not reappear the following year unless weather patterns once again brought spores to the state. The South has no such advantage, especially since its generally warm winters could allow ASR to linger and attack again the next year.

Whether the rust comes north remains difficult to ascertain because so many variables exist. The South boasts plenty of kudzu and crimson clover, two popular hosts for the disease, said Al Bertelsen, a staff agronomist with Agriliance, an Inver Grove Heights, Minn.-based distributor of crop protection products. Whether the spores on the kudzu in Florida have a flight manifest for Minnesota and the Dakotas is anyone's guess. So is whether last year's cold spell in the Gulf states slowed the pathogen's progress in that region.

"It was cold down there, and the rust spores don't do well in that kind of weather," said Neil Caskey, special assistant to the chief executive officer of the St. Louis-based American Soybean Council (ASC). "We sealed the problem for now with that nice freeze, but we still run the risk of it coming up again (from South America) in the wind patterns."

The uncertainty of the situation brings the frustration that comes with waiting and preparing for something that may or may not happen. "The unknown is the worst part—the not knowing when it's going to hit, where it's going to hit and how severe it will be," said Kevin Fridley, director of agricultural services for South Dakota.

Preparing for battle

Agriculture experts widely agree on soybean rust's destructive qualities, but they uniformly believe the bark may be worse than the bite and the strategy and products available to fight the disease will diminish the chance for Dust Bowl yields. They point to the district's luck of geography combined with a federal monitoring effort, continued local media attention, successful ASR information programs, state-sponsored rust Web sites and early approval of fungicides as indicators of a region prepared for the worst.

"We're extremely concerned that this is a very serious soybean test," said Friisoe. "But since we're the most northerly soybean-growing state, we are the least likely to get the disease, and we'll be able to know early if there's a northerly progression of the disease." Being last in line to get the disease means being first in making appropriate preparations to protect crops before potential infection. Should disease hit Iowa or Illinois, the two leading soybean-producing states, farmers in the Ninth District would likely begin to determine when and how much fungicide they would apply to thwart the disease's spread, he said.

Another important part of the preparation has been the federal government's effort to form an early-warning monitoring system using "sentinel plots" in soybean-growing states, said Marty Draper, a plant pathologist at South Dakota State University. States will have five to 20 test sites, some even more, where scientists will observe soybean plants on a regular basis to determine if they have been infected by ASR spores, he explained. The federal government also has begun creating Web sites for monitoring the spread of the disease, should it hit, and to offer a one-stop shop for information on prevention and treatment.

Johnson, the North Dakota commissioner, said trade journals and local newspapers have been filled with articles about ASR. "The press has done a good job on this topic," said Johnson. Meanwhile, the national soybean council held five high profile meetings in the Midwest on ASR last year and this year, including a July conference in Mankato, Minn., and a later one in Sioux Falls, S.D., which drew more than 350 participants. "Our meetings have been well attended," noted Caskey, from the ASC.

As a key source on the disease in South Dakota, Draper has appeared before many groups and has come away with a decidedly different view. "When I think about whether [farmers] are prepared, I have mixed feelings," he said. "When I talk to grower groups, I wonder about how prepared they'll really be and if they realize that treatment is going to be a costly thing." If ASR hits, however, he thinks the crush of publicity will force farmers to seriously invest in fungicides to prepare their crops for a potential influx of the disease.

Helping in battle preparation has been approval of several new fungicides that will assist farmers in avoiding the decimation of their soybean crops. "It all depends on how many times you have to spray, but I wouldn't expect us to run out of fungicides (nationally) in a one- or two-spray scenario," said Bertelsen, from Agriliance. "We have a lot of time to prepare, and companies can make more fungicide during an infection to meet demand."

Several Asian soybean fungicides have received approval from the Environmental Protection Agency under an exemption called Section 18. This exemption allows growers to use the fungicide for three years before having to seek another approval. The EPA requires that states request Section 18 exemptions on an individual basis, and as of late February, Minnesota and the Dakotas had secured exemptions for chemicals such as propiconazole (sold as Tilt, PropiMax and Bumper), tebuconazole (Folicur), trifloxystrobin and propiconazole (Stratego) and myclobutanil (Laredo).

They add to a list of four other chemicals approved nationally for use against the disease. To be effective these fungicides should be applied before the soybean rust appears and during its assault. Farmers who find rust can apply triazole fungicides—which serve as a preventive chemical, too—to stem the disease in its early growth stages. But once lesions occur on the plant's leaves, there's little that can be done, according to Bertelsen.

Web sites devoted to the disease suggest spraying must soak soybean fields to penetrate the lower canopy, where rust begins its destructive process. Crop rotations will not work since the disease is airborne. Given that they don't use chemicals, organic soybean producers could take a bigger hit than traditional farmers. Farmers will see their margins diminished if they have to buy fungicides, especially if they have to spray more than once, Draper said.

The decision about when to spray is an enormous challenge since ASR is a new disease. Generally, ASR hits during or after soybeans flower, leaving farmers with the unenviable decision of when to spray. Too late, and they'll see their crops die; too early, and the fungicide may lose its effectiveness or require another spraying, Draper said. Initial fungicide sprays last approximately 14 days; a second coat adds another 20 days. "There is going to be some gambling going on with the question of how close do you let it get to you before you spray?" he said.

For some farmers the cost remains part of the price of doing business. "It depends on the severity of the outbreak, but I can do a custom application for $5 an acre and at around $8 an acre if someone else does it," said Mechtel, the North Dakota farmer and president of the state soybean association. "Even if we do a couple of applications, it will still be cost effective. It'll cost the equivalent of three bushels an acre of soybeans for producers."

For now farmers are in a waiting pattern. Draper sees a high probability of ASR, if only because the region has seen wheat rust arrive from the South while following wind patterns commonly found operating between the two regions. If ASR does not come this year, it could come next year, especially if it becomes established in Mexico or Central America. It's a disease that keeps on giving.

Mechtel has made the decision to bet the farm on soybeans. His neighbors, meanwhile, have chosen to hedge against ASR by planting sunflowers. He appreciates their caution even if he's not joining them. "It's on everyone's mind here, and there's a certain amount of anticipation," he noted. "But there's also a lot of possibilities and opportunities for us."