Asian soybean rust spreading in Florida

Three Florida Panhandle counties — Okaloosa, Santa Rosa and Holmes — have new cases of Asian soybean rust in sentinel plots. They won’t be the last.

“We’ve listed three new sites but there are more pending that will be confirmed shortly,” said David Wright, Florida Extension soybean specialist on Thursday morning. “By now, we know what this rust looks like. It’s on the move.”

In Gadsden County, where Wright is based, soybean rust was found on kudzu earlier this year. Yesterday (Aug. 10), the disease was found in three sentinel plots in the county.

Wright said rust was also found in two Jefferson County sentinel plots on Tuesday (Aug. 9).

Adding to the growing list, rust was also discovered on kudzu in Taylor County — a coast-side county southeast of Tallahassee.

“At this point, I truly believe if we went into any Florida county and spent a little time, we’d find soybean rust,” said Wright. “With the weather we’ve had for the last 10 days, it’s moving easily. We’ve had rain and high humidity and continue to get showers regularly.”

Towards late July, “it was hot and dry and that helped keep the rust in check. Then, the showers began and the canopy has been kept wet. In most places, the bean crop is canopied so conditions are easy for infection to take hold.”

Wright said every soybean grower in the state should spray a fungicide. Some already have and some — “especially where beans were double-cropped with wheat” — are gearing up to do so.

Since some producers have sprayed already, has Wright made a recommendation for a second fungicide application?

“If current conditions continue — canopies staying wet until lunch or later — we recommend a second application. We’ve got some very good soybeans with a lot of yield potential. What we’ve got needs to be protected.”

It isn’t just soybeans Florida producers are concerned about.

“Yesterday (Aug. 11), we also found suspected rust in a sentinel plot in Columbia County, northwest of Gainesville. The plot was in a 200-acre field of watermelons followed with green beans. The grower is worried about rust ruining his green beans.”

Most of the soybean crop in Florida is between R-1 and R-4.

“Surprisingly, some of the growers have Group IVs which is not common here. We mostly have Group Vs, IVs and some VIIs. The Group VIIs aren’t going to be harvested until mid-October so there’s plenty of growing season left. The bulk of our beans are looking at mid-September before harvest.”

Because of Florida’s growing conditions, producers are locked into later group beans. “We’ve tried some earlier beans in the past and they didn’t do well. It’s normally very rainy in late June through August. Because of the humidity in the canopy, the pods on the early beans just rot away.

“Many years ago, we looked at early beans to harvest in late July. The seed quality was very, very poor. So our earliest beans shouldn’t mature until mid-September.”

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