Over the weekend, Kentucky reported three and Missouri reported two new counties with Asian soybean rust. The U.S. total rose to 179 rust-positive counties and parishes in 15 states.



Kentucky has 16 positive counties. Missouri has four.



According to the Kentucky state commentary on www.sbrusa.net, soybean rust was found in Ballard and McLean counties in the far western part of the state, and in Hardin County in central Kentucky on or around Oct. 19, reported Oct. 21. All of the finds were in commercial fields of double-crop soybean, and most of the fields are now harvested. These counties join three others found to be positive earlier in the week.



"The timing of SBR observations in Kentucky and SBR spore deposition models, suggest that a large number of spores blew into Kentucky sometime during the third week of September," University of Kentucky plant pathologist Don Hershman said in the commentary.



"Finding soybean rust at this time will have absolutely NO impact on the 2006 soybean crop in Kentucky. In fact, soybean rust will 'go away' from Kentucky as soon as there is hard freeze. It simply cannot survive this far north. However, these finds are of great importance for refining the soybean rust predictive models."



Missouri finds two more counties in final sweep



The Missouri state commentary said that, after soybean rust was found Oct. 13 and 17, "Sentinel plot scouts were asked to make one last survey of their areas to sample any fields which still had either green plants or green leaves on scattered plants in fields.



"As a result of this end-of-the-season survey, soybean rust was found in two new Missouri counties: Stoddard and Scott. In both cases, only a few soybean rust pustules were found on a small number of leaves in the submitted samples."



Scott and Stoddard are the two counties immediately north of known positive counties New Madrid and Pemiscot in the extreme southeast part of Missouri known as the Bootheel.



"Samples from Ste. Genevieve, Carroll and Boone counties were negative," the commentary said. "Because of harvest and frost, remaining scouts were unsuccessful in finding any green leaf tissue to sample and submit.



"Frosts in much of the state the end of the week of Oct. 9-13 and again the week of Oct. 16, as well as harvest moving along rapidly, mean that the possibility of further detections is decreasing rapidly."



Nationally, including reports of soybean rust found on kudzu, there are 179 counties in 15 states with rust this year: 26 in North Carolina; 24 in Louisiana; 21 in South Carolina; 18 each in Arkansas and Florida; 16 in Kentucky; 15 in Georgia; 13 in Alabama; seven in Illinois; four each in Indiana, Mississippi, Missouri and Texas; three in Tennessee; two in Virginia.



Of those 179 counties, 155 of them represent soybean rust found on this year's soybean crop vs. on kudzu, the other major host of the disease. Kudzu is known to harbor the fungus over the winter if green tissue is present in the absence of a hard freeze.



SOURCE: State and national commentaries on www.sbrusa.net.