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More states report spore traps in place to detect rust
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6/16/2005 9:40 a.m. CDT -- Two more states have identified counties where they are using spore traps to try to detect wind-born Asian soybean rust spores, after Tennessee announced its 10 spore traps placed across the state from Memphis to Knoxville. Alabama and Kentucky added the information to their state commentaries today. (See below.)
Melvin Newman, Extension plant pathologist with the University of Tennessee, described the traps he uses as tubes 4 inches in diameter and 15 inches long with a Vaseline-coated glass slide at one end. A wind-direction tail keeps the open end of the trap always facing the wind.
Once or twice a week, he said, they will collect the slides and see what has been trapped.
“The bad thing is, you collect everything in the air – dust, pollen, other types of rust spores,” Newman said on Monday. “In Brazil, they’ve had fairly good success with spore traps.” The hope is to detect Asian soybean rust spores in the traps even before infection occurs in the immediate area.
New spore trap locations and brief state updates from this morning
Alabama 6/16/2005:
Syngenta spore traps have been set up in Baldwin, Escambia, Lee, Elmore, Pickens, Henry, DeKalb and Limestone counties. These will be checked every 3-7 days. There are 40 sentinel plots in 25 counties in Alabama.
Forecast Outlook -- The tropical storm may have spread rust spores into the mid-south states from sources in Florida or the Caribbean. We are unsure because we do not know if soybean rust overwintered in the Caribbean and, if so, to what extent the inoculum potential might be. It takes 5-10 days from the time of leaf infection until symptoms are observed, so we could see symptoms of rust on soybeans and kudzu in Alabama by the end of this week or early next week. Inoculum (rust spore)levels in the Florida sites appear to be building steadily. The disease has not been found in Alabama in 2005.
Florida Update 6/16/2005:
Observations -- Asian soybean rust was first confirmed on kudzu in Dade County in 2005. On June 15, it was found on kudzu in Jefferson county. There are now a total of five counties in FL with positive confirmations of soybean rust: Dade, Hernando, Pasco, Marion and Jefferson. All confirmations are on kudzu.
Growth Stages -- Soybeans in FL are flowering or approaching flowering (V5-bloom). Most sentinel plots are blooming; some sentinel plots are at R3. Kudzu vines are growing rapidly and closed canopies maintain humidity and lower temperatures -- an environment conducive to disease.
Kentucky 6/16/2005:
Spore traps have been set up, and are being monitored, in the following counties: Ballard, Caldwell, Calloway, Fayette, Hardin, Henderson, McLean, Shelby, Todd and Warren.
Ontario province commentary 6/16/2005:
Observations -- Thirty-eight sentinel plots have been established and sentinel plot scouting will continue this week.
Growth Stages -- Soybean growth stages within the sentinel plots range from second (V2) to fourth trifoliate (V4). The Ontario soybean crop is in fair to excellent condition. Plants range from the unifoliate to 3rd trifoliate leaf stage. Moisture stress is evident in some parts of the province that have missed recent thundershowers. Soybean aphids have been found in a number of fields from Windsor to Fergus. 10 to 50 aphids on a few plants scattered in a field are being observed. These levels are well below spray thresholds.
Management -- No management recommendations necessary for soybean rust in Ontario at this time. The implications of tropical storm Arlene won't be known for 7-10 days.
Forecast Outlook -- The risk of soybean rust in Ontario is low at this time. Continue to monitor the southern U.S. soybean rust situation for inoculum build-up and/or potential spore movement into Ontario.
Source: USDA site www.sbrusa.net.
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