Asian soybean rust was found in soybean sentinel plots in a second South Carolina county -- Orangeburg -- Monday and yesterday.



This is the second location and county to have rust in South Carolina this year. Rust was found in Calhoun County Aug. 17. There are now 37 counties and parishes in the U.S. with soybean rust in 2006 in seven states, including on soybeans in six of the states.



Today's state commentary on www.sbrusa.net reported:



"Rust was identified on leaves collected Aug. 28 from MG 4 and MG 5 sentinel plots in Orangeburg County. Initially, six of 50 leaves from the two plots were infested. Four of the leaves had only 1 to 5 lesions with multiple pustules. Two of the leaves had 15+ lesions with multiple pustules.



"Three-hundred-twenty more leaves were collected on Aug. 30. Approximately 10 percent of these leaves were infected. 20 percent of the infected leaves had 10+ lesions with multiple pustules.



"This is the second location and county (Calhoun and Orangeburg) in South Carolina with rust. No rust has been observed on kudzu in South Carolina in 2006.



"The high relative humidity the past week along with the rain from the hurricane this week and the low temperatures and thunderstorms forecast for next week should be very favorable for the development of rust and other soybean diseases."



State officials made the following spray recommendations today:



"Rust is probably present in South Carolina in more than just these two locations. Scouting of individual fields may be warranted.



"Some important points to remember in making spray decisions are:


  • Soybeans that have not flowered do not need to be sprayed.


  • Soybeans that are at or past R6 should not be sprayed.


  • A strobilurin or fungicide combination containing a strobilurin should be sprayed if you want to control diseases in addition to rust.


  • The incidence of rust in South Carolina is still relatively low, but conditions are favorable for rust to spread within and between fields.


  • If you are going to spray a fungicide in the next week, you need to include a strobilurin in the spray to optimize control of the most diseases possible. These sprays should be especially effective in high-yield potential soybeans with a full canopy that are R3 to mid-R5 in growth stage."



    SOURCE: South Carolina state commentary on www.sbrusa.net.