|By ANN HINCH
KNOXVILLE, Tenn. — Many people who dodge a bullet thank their lucky stars and go on. Not plant experts with the University of Tennessee (UT).
They are using last year’s surprising statewide reprieve from Asian soybean rust (Phakopsora pachyrhizi) to refine preparations for when the fungus’ spores do cause a problem for bean and legume growers, and to improve communication about it.
To that end, UT updated its call-in service for farmers to a toll-free rust hotline; the number is 877-875-BEAN (2326). In 2005, it was a personal voicemail recording only one person at a time could call in to hear, and coordinator Elizabeth Long is glad for the expansion.
“It’s basically for us to rapidly share information … on what’s happening in Florida, what’s happening in Texas, what’s happening in Tennessee,” said Long, an extension specialist in entomology and plant pathology.
Each Monday morning, Long and other specialists - from Florida north to Illinois and west to Texas - will host a conference call to discuss the prior week’s rust news. She will update the hotline recording by 1 p.m. EDT that day. Breaking news will be added as necessary other days of the week.
“We’ll blow the whistle if we see rust coming, and we feel like it’s a good enough threat,” assured fellow extension plant pathologist Melvin Newman, who works on the other side of the state from Long.
While the hotline is geared primarily to Tennessee growers, he encourages any regional farmer to call in to monitor the situation.
Because rust spores generally travel north from South America through the Caribbean, the South is sort of the canary in the mineshaft for the rest of the United States.
Indeed, rust has been confirmed this year on kudzu plants in Florida, Georgia, Alabama and southern Texas. A native Asian vine, kudzu is the soybean fungus’ other major target.
“We wouldn’t have much problem with this rust if we didn’t have this kudzu,” Newman lamented.
So far, no sentinel soybean plots have been infected, though Newman pointed out the spores are present.
Last year, Florida, Alabama and Georgia did have outbreaks of what he calls “damaging” soybean rust. In western Kentucky, one leaf of one kudzu plant was confirmed infected. Tennessee escaped.
“I won’t take credit for all of it,” Newman joked. “County agents across the southern part of the state and I set up some big fans and blew the rust in the other direction.”
While spores did settle on Tennessee plants, he said climate conditions weren’t right for infection to take hold.
Early heavy rains turned to dry weather in the nick of time, robbing the fungus of its preferred moist, hot incubator in the earliest stages of soybean development – when it is most vulnerable. Long added once the plants start setting bean pods, they seem more resistant to disease.
Not even wind and rain from last year’s record Gulf hurricane season increased infection. Whether it was too late in the year or the sheer volume of water drowned out viable spores, it was one of the few problems Katrina and her kind didn’t cause.
“We kept watching these storm fronts come through, and thinking ‘Oh, surely there’s something being blown up here,’” Long explained.
It is suspected late 2004 hurricane winds are exactly what brought rust spores to the United States at least two years earlier than predicted. Straggling soybean plants in seven southern states, including one plot in Tennessee, were confirmed infected two months after Hurricane Ivan.
Fortunately, it was after harvest and the damage was largely an academic curiosity which gave plant specialists several months’ warning before the spring growing season.
Long will use the hotline to give notice of other fungal soybean disease trends if they crop up, but specialists are focusing on Phakopsora pachyrhizi.
“Soybean rust is really what’s on the grower’s mind, because we’ve never had to deal with it,” she pointed out.
Newman said the 10-15 trizole-based chemicals (specifically developed against rust) approved for spraying worked “pretty good” last year. There are five more he believes EPA is close to approving.
Whether to spray early is a management decision, though he encourages growers to save money and still their nozzles until rust is reported sufficiently close enough to worry.
“We know what the enemy is now,” he said, more confident than a year ago, “and we think we can handle it.”
There are also multiple online resources for soybean growers, including the USDA website at www.usda.gov/soybeanrust and the Southern Plant Diagnostic Network at http://spdn.ifas.ufl.edu/soybean_rust.htm
This farm news was published in the May 24, 2006 issue of Farm World.