Goss's Wilt marching towards Ontario

Tuesday, October 4, 2011

by KAREN BRIGGS

A bacterial disease previously confined to corn crops in Kansas, Nebraska, Colorado, and parts of South Dakota is headed north and eastward towards Ontario.

“Goss’s Wilt has been on our radar for the past few years as we’ve watched it expand into Illinois, Wisconsin and Michigan,” says Albert Tenuta, a field crops pathologist with the Ontario Ministry of Agriculture, Food, and Rural Affairs.  “I would not be surprised to see it here shortly – possibly by next year.”

“We’ve just completed our annual survey of (corn) diseases, and there were no confirmed cases (of Goss’s Wilt) as of the beginning of September,”Tenuta says.  “But does that mean definitively that it isn’t in Ontario?  Without sampling every field, we don’t know for sure.”

The disease disrupts the vascular system of the corn plant, restricting the movement of water and nutrients and leading to reduced yields.  Stunting, wilting, and premature death of plants can contribute to up to 50 per cent yield loss to susceptible hybrids infected early in the growing season.

Crops which have been pummelled by wind or hailstorms are particularly vulnerable because the damage to the plants gives the bacteria an entry point.

Harvest and tillage equipment, balers and wind all can carry the bacteria to uninfected acreages.  So can weather that transports infected residue. Once established, the infection can persist for years in soils.

“Goss’s Wilt has probably been spreading thanks to wet conditions in the corn belt,” says Tenuta.  “Foliar diseases like those conditions, so it’s not surprising that we’ve seen movement over the past five to 10 years, from Nebraska into the corn belt and beyond.”

Because Goss’s Wilt is bacterial in nature, there are no effective in-season management options. To help avoid spread of the disease, growers should clean equipment of crop residue, harvest and till infected fields last, and increase their use of deep tillage and crop rotation.

Prevention, however, is the best strategy, and that requires planting resistant hybrids developed to thrive in locations where Goss’s Wilt is endemic.

“Growers are always experimenting with different hybrids anyway, so resistance to Goss’s Wilt will just become one more thing to consider when selecting a hybrid,” says Tenuta.  He isn’t aware of any hybrids currently tailored  for Goss’s Wilt being sold in Ontario. But it shouldn’t be difficult to obtain them should the need arise. Hybrids with a 7 or 8 rating for Goss’s Wilt are available in the United States. 

“It’s not something to panic over,” he adds.  “It’s just a natural progression in growing crops.  Diseases come and go.  We have a good track record here in Ontario of managing our diseases and pathogens, and a lot of it is in hybrid selection.

“Growers can reduce their risk for next year just by scouting their fields for problems this fall.”

Crosby Devitt, manager of market development and research at the Grain Farmers of Ontario, says, “Goss’s Wilt really hasn’t been an issue here yet, but it is something we’re keeping tabs on.  Should it end up (in Ontario) our growers will want to know about the symptoms of the disease and what they can do in terms of control and management.

“We keep in close contact with U.S. disease-monitoring programs, and at the end of every season we review our priorities for future research.  That’s something we’re doing right now.

“If we see that Goss’s Wilt is likely to be a factor next season, we will take action.” BF