You are here

Varietal Resistance Still Key in Managing Corn and Soybean Disease

Back in 1970, Southern corn leaf blight cut a
scythe-like swath of withered plants, broken stalks, and rotten cobs across the
United States.
Hybrids
were vulnerable because a new strain of fungus cracked a "genetic
window" regarding a gene found in the cytoplasm.

This experience lingers more than four decades
later. Yield potential remains a major goal when breeders develop new corn
hybrids and soybean varieties. Still, disease resistance ranks high when
companies release new seeds. That’s good news if you’re concerned about
fighting corn and soybean disease. For now, resistance remains the top way to
battle disease, with fungicides in reserve in case this first line fails.

“I don’t see breeders dropping breeding for
disease resistance as a major objective,” says Paul Vincelli, University of
Kentucky Extension plant pathologist. “But


if plant breeders breed for higher
yield by cutting out resistance genes and instead emphasize drought tolerance
and other things, there could be cases where we get an erosion over time of
background resistance levels. Then fungicides become a tool not just for
improving profit margins, but as an umbrella protecting hybrids from fungal
diseases.”


Resistance is improving

It’s impossible for
plants to resist every
disease. However, disease resistance is improving through technologies like
marker-assisted technology, says
Bill Dolezal, a
DuPont
Research Fellow at DuPont Pioneer. If a new fungal disease surfaces in a
region, fungicides may be required to control it in disease-susceptible
hybrids. Still genetic resistance remains at the firm’s forefront, as Dolezal
adds it’s a matter of environmental stewardship.

“Our goal is not to apply any more chemicals
than necessary,” he says.
“Speaking for the DuPont Pioneer plant
breeding group, we will not reduce our effort of genetic control of disease and
insect pests.”

Read more about