No Asian soybean rust has been found in Arkansas this year and if it is in the state, Cliff Coker isn’t expecting the disease to do much, if any, damage.
“We’re running 20 to 25 sentinel plots around the state,” said the Arkansas Extension plant pathologist. “They’re scattered up and down the Delta and across the southern part of the state.”
Prior to the ASR findings in Louisiana and Mississippi (see http://deltafarmpress.com/news/060801-asr-mississippi/), the plots were checked weekly. Since the discoveries to the south, “we’ve picked up the monitoring pace.
“Even after intensifying scouting — especially in the southern part of the state — we’ve found nothing in the sentinel plots, grower fields or kudzu patches. At many locations, we’re scouting two or three times weekly, pulling samples, bagging them and checking them the next day for any evidence of sporulation.”
The late July/early August weather pattern has remained unfavorable for ASR.
“A bit of rain ran through the state recently, but didn’t change things much.”
In Monticello, Ark., where Coker is based, “those rains basically just settled the dust. It’s still very dry.”
The main thing to remember is it takes “very moist” and, for Arkansas, cool temperatures for ASR to become established and cause yield impacts. The current weather pattern (95-plus degrees with little rain through the first week of August, at least) isn’t favorable for rust.
“Even in a worst-case scenario — a few spores land on a wet leaf — it would be six weeks before it could build to a level of concern. By that time, our crop would have been finished for a while.”
If that worst-case scenario actually occurred, “I suppose there’s a small possibility of yield impact on some very late-planted beans behind wheat. But the yield target for those beans is probably 30 bushels, or less. It would be very difficult to justify a fungicide application on those.”
If ASR is found, the area county agent will be notified immediately. Then, “an alert would go out to the farmers, the media, everyone. The goal is within 24 hours, everyone would know ASR was in the state. But I don’t see rust being a problem this year in Arkansas.”
As for other soybean diseases, a bit of frogeye leafspot has shown up in the crop. However, the bulk of the state’s soybeans are already at R-4/R-5, so it won’t impact yields.
“There’s also a touch of aerial blight in northeast Arkansas. There have been a few fields sprayed but that’s not abnormal. We always have aerial blight applications to protect 60-bushel beans. We’re in good shape because it’s been so dry.”