Pulling the trigger

BROOKINGS, S.D. -- In a decade as South Dakota State University's Extension Service entomologist, Mike Catangui has worked to become the go-to source for entomology information for his state's farmers.

BROOKINGS, S.D. -- In a decade as South Dakota State University's Extension Service entomologist, Mike Catangui has worked to become the go-to source for entomology information for his state's farmers.

But recently, Catangui acknowledges he's become something of an "outcast" -- certainly a"rebel" -- among his fellow university entomologists because of his spray recommendations involving a single pest, the soybean aphid.

Based on his own research since 2003, Catangui recommends spraying for the aphid when farmers and consultants see as little as one to five aphids are seen per plant, depending on the plant stage.

A large consensus of other entomologists in surrounding states -- led primarily by David Ragsdale at the University of Minnesota -- recommend holding off spraying until aphid levels reach 250 aphids per plant. That includes a colleague, Kelley J. Tilmon, at SDSU, as well as entomologists in North Dakota and the Red River Valley. The disagreement between the two camps recently was a hot topic at the North Dakota Soybean Expo in Fargo.

Farmers could be wasting money to use Catangui's recommendations, Tilmon and the others say, and they could be unwittingly killing the beneficial insects requiring subsequent spraying.


But Catangui's is not without supporters.

Among them, he has Ben Kantack, a predecessor in his job and a South Dakota Hall of Famer. And then there are Brian and Darren Hefty, owners of the Hefty Seed Co. in Baltic, S.D., and hosts of the popular "Ag PhD" television and radio programs.

The only thing the two sides agree on is that millions of dollars are at stake in a crop that has expanded acreage significantly in the region in the past decade and is expected to increase in acreage in 2008 because of market prices and input costs.

Catangui's America

Mike Catangui has his own fable. He grew up in the Philippines, the son of schoolteachers, and at age 10 he was taking care of his family's rice fields. He got his bachelor's degree in agricultural from the University of the Philippines and moved to the United States in 1986 when he was 23 years old.

He came to South Dakota State University to work on his master's degree in entomology in 1986 and 1987. He worked on grasshoppers in rangeland as far north as Amidon, N.D. At SDSU, he also worked in Bt corn technology under Murdick McLeod, a North Dakota native, who went on to Pioneer Hybrid. Kantack also was at SDSU when Catangui was working with McLeod, but the two didn't know each other personally then.

Catangui went on to acquire his doctorate in entomology at the University of Nebraska in Lincoln in 1992, specializing in stable flies, a feedlot cattle pest. He spent summers from 1987 to 1991 doing research in North Platte, Neb. He had an assistantship in which he worked on corn, beans, sunflower and alfalfa. In 1993, Catangui returned to South Dakota State University as a postdoctoral research associate. He became an extension entomologist in 1997. He and his family live in Sioux Falls, S.D., about 55 miles south, and he commutes to work.

Since 2003, Catangui has conducted his own research on soybean aphids. Unlike other research, his research observes the buildup of aphids in an enclosed cage, which doesn't allow in predatory insects and other influences that can suppress aphids.


Behind Catangui on the aphid issue is Kantack, 80, something of a legend in South Dakota. Kantack also received his doctorate in Nebraska, came to SDSU in 1962 and became extension entomologist in 1963. He retired from that post in 1990 and the SDSU dean of agriculture at the time dubbed him a living legend. Kantack later was honored by the state South Dakota State Legislature and the governor. He also was named to the South Dakota Hall of Fame in 1998.

While no longer SDSU's official voice on entomology, Kantack isn't shy about offering his opinion. Despite his age, he remains active as a crop consultant for a nearby Hutterite colony and several farmers. Kantack is confident in Catangui's recommendations.

"He's proven it three years in a row in the field," he says.

Kantack says that if the population is "allowed to build up," as in his closed cages, the population will "double every five days."

The recommendations require treating within seven days, but now that bean prices are higher, some entomologists are suggesting a shorter window. Kantack says farmers who follow that threshold -- even with the smaller spray window -- are at risk.

"Aphids spread so fast, they're risking taking a helluva loss,' he says.

"If the wind is blowing, you maybe can't spray for a week," Kantack says, noting he tried to use the 250-aphid guideline for a farmer-client in 2003 and it ended up failing. "I would say I lost 10 to12 bushels," although he acknowledges he didn't take specific measurements of the loss.

Despite all of this, Catangui's underlying research philosophy is largely rejected by counterparts in other states -- precisely because it excludes the beneficial insects.


Tilmon came to SDSU in May 2005 as a research entomologist. She is an assistant professor, primarily focused on soybeans.

Before her current post, Tilmon was in a postdoctorate program at the University of Wisconsin. Her doctorate is from Cornell in Ithaca, N.Y.

Tilmon and Catangui's boss, Sue Blodgett, is chairman of the SDSU Plant Science department and was a field crop entomologist who came out of Montana.

Recently, Blodgett added an extension appointment to Tilmon's responsibility. It adds to the "team approach" being implemented in various disciplines at SDSU, Blodgett says.

"It gives me time to extend some of my research results to the end-users," Tilmon says, declining to discuss whether this conflicts with Catangui's responsibilities.

Tilmon's recommendations, based on her own research at SDSU, are similar to those of Ragsdale and other university researchers. Like them, Tilmon says the cost of inexpensive "insurance' treatments are not justified and in fact can lead to other problems. She says vigilant scouting is the only way to know when aphid populations will explode.

She recommends a spray threshold at an average of 250 aphids per plant, throughout the field, and only through the R5 growth stage, when seeds are beginning.

"This threshold is based on several years of extensive research at South Dakota State University and at the land grant universities in Iowa, Michigan, Minnesota, Nebraska, North Dakota and Wisconsin," she writes in a recent -- and official -- SDSU Extension Factsheet on soybean aphid biology and management.

Including her Tilmon's own trials, 22 experiments were done in 2006 across the Midwest, she says.

"Though some producers may feel that to avoid damage they should treat before aphids reach an average of 250/plnat, the needed safety factor is actually already built into the economic threshold," she writes. "The economic injury level, where yield loss justifies the cost of treatment, is around 675 aphids/plant, on average."

Tilmon says the effect of premature spraying on beneficial insects is not a matter of belief.

"We have experiments from many researchers and states showing that predators provide a significant amount of background control," she says. "Sometimes aphids do escape that control. That's why continued scouting is important. No one is suggesting we walk away and allow natural enemies to take care of it. We are suggesting that they are allowed to do their background control, and if aphid populations build, in spite of that control, we take action.

"The philosophy is to spray when needed, and not to spray when you don't need to," she says. She says it's been calculated that if even 5 percent of South Dakota's soybeans acres are unnecessarily sprayed with an insecticide, it costs growers about $2.3 million.

Including the price of beans

Catangui says the spray trigger should be heavily influenced by the price of beans, which has increased dramatically.

"Here's something you can relate with, being from North Dakota," Catangui says. "If you think about it, sunflower is very valuable. The market value is 20 cents per pound or more. How much is the soybean on a per-pound basis? It's about the same, or catching up to sunflower.

"Ask your (NDSU) entomologist what is the threshold is for the sunflower moth? The threshold for spraying is less than two per hundred plants. Nobody blinks about that," Catangui says, later clarifying that this is only a rough analogy.

Meanwhile, he says, people are "complaining" about his recommendation on soybean aphid spray threshold, which is about two to five per plant, depending on the stage.

"Soybeans are now more than double the price from last year," he says. "How come the threshold from Minnesota is never changing?"

Catangui says that farmers realize it takes less than a bushel in bean value to pay for the spray.

"What we've been saying over the years is that the threshold should reflect the market value of the crop, as well as the cost of spray and the yield potential for a field," he says.

If a field historically yields 60 bushels an acre, a farmer can afford to spray at a lower threshold than someone else that who has a field that averages 30 to 40 bushels, he says.

The 250-aphid-per-plant threshold's only claim to fame is that it's "from a major university," Catangui says.

In an overarching concern, Catangui thinks farmers "don't have a lot of trust anymore, in extension." He says the extension experts come up with "something they agree upon," but then don't change that that assessment. "They set a recommendation and put their weight behind it over the years," but says "now the people are smart. How in the world can you convince somebody not to spray if the market price has more than doubled?"

Catangui also sees a bias in the entomology community.

"These people have their own anti-insecticide agenda," he says, without naming individuals. He notes that many developed their thinking in the context of Rachel Carson, who famously authored "Silent Spring," in 1962, the environmental movement.

"Their main objective is to not spray because to spray is evil. Why don't they just say it: 'It's evil, don't spray,'" he says, adding, "Their main objective is to preserve the beneficial insect, not to improve the bottom line of the farmer."

While other researchers say the tests aren't complete without letting in the predator insects in, Catangui sees this as letting in uncontrollable factors that can "confound your research."

In addition, Catangui notes that the research that led to the 250-aphid threshold also shows that aphids can double in number in three days. If you assume they're right -- a 250-aphid level -- in three days, it'll be 500 and another three days, it's 1,000 "What kind of recommendation is that?"

It's Catangui's contention that the beneficial insects "can't be trusted" to protect the crop, without quantifying those insects first. "That becomes so lazy," he says. "They're assuming they can put their name behind recommendations without proving it."

For her part, Tilmon says any thresholds developed by university researchers is with "the producers' bottom line in mind, and not with Carson." She notes that "just about everybody working in entomology have recommendations for (spray) treatments. I don't know any agricultural entomologist who rejects insecticides in the IPM toolkit."

Tilmon says it's not necessary to know the exact level of beneficials in the field to develop thresholds.

"We have research on population growth over a wide range of conditions," she says. "This threshold recommendation is based on extensive field studies performed by many entomologists throughout the Midwest, not just one person; it is the result of rigorous research, not opinion or conjecture. The cornerstone of the recommendation is regular scouting to be aware of aphid population levels and when they are actually becoming a problem -- neither a blind faith in natural enemies, nor a blind assumption that very low aphid populations will always explode."

And if populations must reach 675 aphids per plant before it causes a significant yield loss, then that's true no matter what price the beans are.

"Beans could be $100 a bushel, and if there's no yield loss, you're wasting your (treatment) money," she says.

She says it also is worth noting that the composite information from the 22 research trial) is that there is no yield loss associated with using the 250-aphid threshold -- this was the context for the above comment about $100 bushel beans, though you certainly capture the heart of it with your reference to the economic injury level.

Tilmon notes that all university agricultural entomologists she knows offer spray recommendations, so she thinks none of them are "anti-spray."

Judging the journals

One of the recent developments in the story is that Catangui's research was published in the Agronomy Journal, based in Wisconsin, in its March-April issue that came out the first week of March. This is based largely on his research in 2003 and 2004.

In the article, Catangui and the lead author, Eric Beckendorf, with USDA's Northern Grains Insect Laboratory in Brookings, S.D., chronicle a quick build-up of aphids in Catangui's exclusion cages, and their impact on yield and other quality factors.

In the conclusion, the authors suggest "we should be managing aphid populations differently based on soybean plant development stage and dates of initial aphid infestation" and that "stage-specific economic injury levels can and must be developed." The paper doesn't, however, specify these economic injury or threshold numbers that might be different than the 250-aphid levels.

"An economic threshold combines the agronomic data we provided and current economic factors, like the market value of the soybean and the cost of the control," Catangui says. "A threshold is simply an interpretation of agronomic data. The price of soybeans changes every year, the cost of control changes, and the yield potential."

Catangui acknowledges that he tried to get a related -- but not identical -- research article published in an entomological journal that he declines to name.

"That is a long story," he says. He declines to speculate why, but he says the issue of aphid thresholds has "gone beyond science" and the rejection may have been based on "professional jealousy."

Catangui is proud that his research was featured on the front page of the prestigious journal.

"Nobody has the right to discriminate on some idea just because it's a small-time researcher," he says. "That's why the (Agronomy) Journal is an equalizer. Anybody can publish, if your data is sound."

Blodgett acknowledges Catangui's research and article are important because they show a good picture of the theoretical growth of aphids in protected conditions. "The next step is to look at this in a more natural setting," she says.

Tilmon notes that the Journal of Economic Entomology in 2007 published a soybean yield response study, which offers very specific threshold levels -- the same ones she and other university entomologists are endorsing.

"People usually want an easy answer," Tilmon says, acknowledging that farmers and consultants are very busy during the scouting season. "What the university sometimes offers are complicated answers.

"There are always differences of opinion in the scientific community, but when it comes to making university recommendations, we have to go with the greatest weight of evidence," Tilmon says. "With 22 experimental studies conducted by seven states over the course of several years supporting a given conclusion, it's pretty clear where the greater weight of data rests," Tilmon says.

An issue that won't die

Catangui's emphasizes that his image of America, coming from a Third World country, is that people don't suppress information.

"We are America, the United States," he says. "Nobody has a monopoly on information. It starts with academic freedom. The definition of freedom is wide-ranging, not just military. It's freedom of speech."

He says there has been an effort to "suppress" his recommendation. He says the issue has not died down because what he says is true, he says. He notes that the Hefty brothers, agricultural product suppliers, with their television show, are subscribing to and promoting his recommendation.

"How come they're using it? I didn't tell them to," Catangui says. "How come there's a lot of people in Minnesota and South Dakota using my economic threshold, on my Web site? "It's because it's the truth."

When asked whether it's possible the Hefty brothers could benefit from a lower threshold because they sell chemicals, Catangui bristles. He asks whether their recommendations might be believable because they work and make farmers more money. The Hefty brothers are out of the country and unavailable to comment for this story.

So far, it's unclear who is using what recommendations.

Tilmon and colleagues in North Dakota and Minnesota report that a number of industry representatives and retailers who want to communicate the best research-based information. Catangui and Kantack say they know of crop consultants and aerial applicators who believe their philosophy.

Tilmon helped organize recent for rums, participants were surveyed and asked, "Do you plan to use the economic threshold of 250 aphids per plant." Sixty-three percent said yes, 24 percent said no, and 12 percent were undecided.

"The message to me is that among this group of participants there's a widespread awareness that these are well-researched, accurate and safe thresholds," Tilmon says.

Blodgett says most of the people she's talked to are "pretty much using these regional recommendations," especially after SDSU issued its fact sheet ,there is more of united front at SDSU.

"I think the confusion is going to be lessened," she says.

As far as Kantack's influence in the issue, Blodgett says, "Dr. Kantack is retired."

She says there is no repression of information.

"The information we've learned has steadily improved over the years," she says. "As it's improved, our recommendations have changed to reflect that."

Kantack offers this benediction: "Fortunately, farmers will decide when they want to spray and what economic injury levels they want to accept. I, for one, and for my clients in South Dakota, are going to follow economic levels established by Dr. Catangui and the Northern Grains Insect Laboratory. These other states can use whatever they choose, depending on their conditions."


-- Economic Injury Level -- When pest population causes economic damage, defined as when the loss is equal to the cost of implementing a management tactic.

-- Economic Threshold -- Point at which an increasing pest population needs to be controlled to keep it from reaching the EIL. This considers the pest population growth rate and logistics of insecticide application.

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