Soybean growers tracking rust developments

Soybean rust has been found at two sites in Jefferson County in southwestern Mississippi. While rust was heavy on kudzu, it was difficult to find on soybean in sentinel plots. Growers in southwest Mississippi, with beans at the R5 or younger growth stage should consider spraying with a protective fungicide.

At this time rust is not a threat to growers in the Delta and northern Mississippi. Rust spore counts and populations found on soybeans in the southwest part of the state have been low. Plus, extreme heat and dry weather in the Delta and further north in the state have further slowed the movement of soybean rust.

Rust was also found in Louisiana during late July in Rapides Parrish in sentinel plots at the R7 growth stage. These are early maturing, Group V maturity beans. Growers in that area, with beans at the R5 or younger stage, should also consider treatments.

In Georgia, rust found previously on kudzu, has shown up in two sites in south central and southwest Georgia, along the Florida line. Ten samples were taken from beans in a sentinel plot in Quitman, Ga., and all 10 were infected. All the infected soybean samples are located near kudzu, where spores and rust were found, so the movement into soybeans is not a surprise, according to University of Georgia researchers.

Growers in counties near to or adjacent to the Florida line should consider spraying beans that are in the bloom stage. Growers further north in the state should closely monitor movement northward of rust.

No rust has been found in sentinel plots in the Carolinas or Virginia. Likewise rust has not been detected in states north of Mississippi and Louisiana. In Texas, no rust has been reported on soybeans, since an early find on a sentinel plot in the extreme southern tip of the state.

Though the lower tier of states, where rust has been found has received scattered rainfall over the last two weeks of July, extremely hot, humid weather is expected to continue to slow movement of rust from south to north.

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