Asian Soybean Rust Crosses NC State Line

Dr. Jim Dunphy, NC State Extension Soybean Specialist, and Dr. Steve Koenning, NCSU plant pathologist have been keeping a very close eye on the movement of Asian Soybean Rust in the southeast this year, and as of yesterday, rust had shown up in an area where it could be of economic impact to most of North Carolina and South Carolina. Dunphy has this:

“As of Tuesday morning, we have rust in Scotland County NC and York SC and Union county GA are of interest. The western half of the state all has rust within 100 miles of it. That is the target that Steve and I have agreed on that we would recommend spraying,”

Dunphy describes the size of the soybean plant that could be susceptible to rust at an economic threshold:

“If rust is within 100 miles and you have soybeans that are between starting to bloom and having full size beans in the pods in the upper part of the plant, we would recommend spraying those to protect against rust.”

Fungicides are effective on rust, but work better as a preventative than a cure says Dunphy:

“The fungicides we have are pretty effective on rust, but they are much better at preventing than curing. That makes it difficult to manage. The ideal time to spray for the rust is the day before it gets there, but we don’t have a good idea on when that is. WE try to keep people advised where it is, but it’s a guessing game when it might come to your farm.”

And there’s two classes of fungicides that are equally effective explains Dunphy:

“There are two classes that seem to work to prevent are the strobilurins and the triazoles, the vast majority fall into one of those.”

Producers with late planted beans should really consider spraying for rust says Dunphy:

“We have a lot of July and August planted beans out there, they are not that far along, so they have small pods, they are the ones that are vulnerable.”

Dr. Jim Dunphy, NC State Extension soybean specialist.


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