Sudden death syndrome (SDS) ravaged fields in its infection area by more than 33 million bushels last year - triple the losses in '97.
That's according to a national survey of plant pathologists. Growers in states like Illinois, Missouri and now even Iowa believe those figures.
"I had plants that didn't have a single pod on them," reports Don Skinner, Pawnee, IL, who first encountered the disease about eight years ago. "We've had it in areas of about half our fields. Last year, we had it in a 125-acre field really bad."
As the name implies, this pathogen damages or kills quickly.
"In an area the size of a house, it just killed the beans dead by Aug. 15, while the area around it stayed yellow," says Eddie Hoff, Boonville, MO.
That was in 1996 in a creek-bottom field with high productivity. Eddie's father, John, recognized the symptoms from articles he'd read.
Karl Otte Jr., and his father, at Princeton, IA, first got hammered by SDS, in combination with soybean cyst nematode (SCN), in 1995. After some "finger pointing" at possible causes for yellowing beans in a portion of a field, the culprits were confirmed by X.B. Yang, an Iowa State University plant pathologist.
"It devastated the yield, reducing it from about 60 bu/acre down to 30 bu in the affected area," Otte recalls. "It's a highly productive field. The next year we put it into corn, then followed with an SDS-resistant variety that did pretty well."
SDS can start with yellowing beans, but symptoms become classic, notes Hoff. Veins in the leaves remain green while the leaf area between turns yellow and reddish brown. As the disease progresses, leaves dry and fall off, leaving petioles firmly attached to the stem. Look for symptoms around Aug. 1 or when beans start flowering.
Yield losses commonly reach 10-15%, but can hit 70%.
A soilborne disease first identified in Arkansas in 1971, SDS has been spreading northward and has now been identified in at least 15 states. It's commonly found in association with SCN and in lower, wetter areas of fields. It's more prevalent during cool, wet seasons.
SDS is notorious for attacking soybean fields with high soil fertility and top management programs - so much so that it has been facetiously called the "rich farmer's disease."
"Old feedlot areas that have sky-high fertility have been one of the first places to show SDS," Skinner notes.
So what's the best way to control this vicious profit stealer?
Late planting reduces chances of the disease developing. But, as with many soybean diseases, tolerant or resistant varieties are the best weapon for affected fields.
"I spend hours and hours in the winter picking soybean varieties," Hoff says. "SDS and SCN are two of the things I select for, plus yield. If a variety doesn't have SDS and SCN resistance, it's out of the pile."