New soybean virus found in Elgin, Kent

Wednesday, September 19, 2012

by BETTER FARMING STAFF

Soybean vein necrosis  (SVNV), first identified in Tennessee in 2008 and later in several other U.S. states, has been found in Ontario.

Albert Tenuta, Ontario Ministry of Agriculture Food and Rural Affairs field crop pathologist, reported in a newsletter Sept. 14 that the virus has been identified in crops in Kent and Elgin counties. However, this may not be the first year SVNV has been present in Ontario soybeans.

“The disease has most likely been present in soybeans for many years,” Tenuta wrote, “but could have gone misdiagnosed since symptoms look very similar to Cercospora leaf blight (Cercospora kikuchii), scald (sunburn), plant stress response and others.” He says symptoms often begin as light green to yellow patches near the main veins, which may enlarge and eventually become brown areas.  “The veins may appear clear, yellow or dark brown in colour.  The browning of the veins may be especially noticeable on the lower leaf surface but this may not always occur.”

Tenuta said in his newsletter that “the virus belongs to the Tospovirus group which includes tomato spotted wilt virus which are vectored by thrips and possible other insects.” 

Purdue University’s plant and pest diagnostic laboratory also identified SVNV in crops in Indiana this month for the first time, although scientists there also suspect it has been around for longer.

Purdue extension plant pathologist Kiersten Wise, quoted in a report by WLFI-TV in Lafayette, Ind., said they suspect they are seeing the virus this year because they have also seen more thrip damage in soybeans. Wise said the disease does not seem to affect yield. BF