While not rapid, Asian soybean rust continues to spread in Alabama. The latest infected sites are the northern-most yet discovered in the state.
“Early Thursday morning (Aug. 18), I found rust in a sentinel plot in north Talledega County near Renfroe,” said Ed Sikora, Extension plant pathologist Friday morning. “That’s about halfway between Birmingham and Anniston in the east-central part of the state.”
The plot’s soybeans are at about R-6. Sikora found two lesions on two leaves.
“It was nothing major, the rust was just beginning.”
After finding rust in the plot, Sikora drove to a nearby commercial soybean field. “The field is about 18 acres at R-3/R-4. The grower allowed me to scout and I found a lesion on one leaf along the tree line. I took both samples back to the lab last night and confirmed the rust under a microscope.”
The commercial field hadn’t been sprayed with a fungicide.
“Frogeye was just beginning to show up in the field. I suggested the producer hit his crop with a tank-mix or pre-mix to give protection until season’s end.”
From Talledega County, Sikora traveled north and east to three other counties — DeKalb, Etowah and Calhoun. In them, he checked five commercial fields and three sentinel plots and found nothing suspicious.
Soybean rust isn’t the only disease to keep in check with fungicides, said Sikora.
“This year, we’re having a tremendous frogeye problem. That alone doesn’t mean growers are looking to spray a fungicide, though. I’m guessing the vast majority of growers — 95 percent, maybe — haven’t typically sprayed fungicides in the past.”
However, since Asian soybean rust has come in, “I’m seeing more spraying. There’s a great deal of interest in fungicides now. Maybe half the crop, or better, has been sprayed. But that’s just a guess.”
Soybeans that have been properly maintained in the state “have really good potential. Growers that have put out a fungicide already have kept fields clean. “However, in fields that haven’t been treated, I’m seeing tremendous frogeye damage. There’s also some major damage from grasshoppers. Even without rust, those fields will see a significant yield drop.”
Through August, Sikora anticipates new reports of rust movement every couple of days. “Favorable weather conditions are here but the problem doesn’t appear to be blowing up. I just see it continuing to spread slowly.”