Soybean Rust making fast late-season push; no damage foreseen

 

 

Asian soybean rust is making one final - but likely futile - push northward in an attempt to cause yield-damage to the most important oilseed crop in the US.

 

Infestations have been reported in 45 counties across nine states since Friday (Oct 2) alone.

 

"Soybean rust was reported in Gallatin, Saline, and White counties in Illinois and in five new parishes in Louisiana," on Monday, the USDA said via its public rust Web site.

 

"During the first week of October, the disease has also been reported in multiple counties in Texas, Oklahoma, North Carolina, Tennessee, Louisiana, Kentucky and Alabama."

 

The fast-moving airborne fungus has now been found in a total of 16 states and more than 325 counties throughout the Southeast, Delta, southeastern Plains and lower Ohio Valley, in fields as far north as eastern Virginia and Posey County in extreme southwestern Indiana.

 

"It is likely that soybean rust may be present at low levels in other areas in southern Indiana," said Purdue University extension plant pathologist Kiersten Wise. "However, the level of disease in Indiana is very low at this time, and the vast majority of the soy crop is past the point of economic damage occurring. Currently there are no spray advisories issued for soybean rust at this time in Indiana."

 

The USDA said that as of September 28, 63 percent of all US soy had reached at least the leaf-drop stage of development, considered the point of full maturity, at which rust can no longer cause measurable yield loss.

 

"There is currently no soybean rust in Maryland," said University of Maryland Extension Plant Pathologist Arv Grybauskas. "It is now possible to have spore-showers bring Asian soybean rust into our area (but) if a low level infection...were found in Maryland today, it would still take about 30 days for the disease to build up to damaging levels. It is therefore highly unlikely that any of our crop is at risk of yield-loss."

 

The latest USDA infection forecast said a pair of storm systems will organise over the Rockies and move eastward this week, producing widespread rain across the Midwest and Deep South conducive to the spread of rust, which flourishes in mild, wet weather.

 

"Spore transport will occur from the Mid-Atlantic coast, through the Southeast, northward through the Ohio Valley and all the way into southern Michigan/Wisconsin due to winds ahead of the storm system," warned the agency.

 

Soybean rust - which is a major crop pest in other areas of the world, and can only be countered through the timely application of chemical fungicide - was first found in the continental US nearly five years ago, but has yet to cause appreciable damage.