Break In Corn Rootworm Resistance Renews Interest

Break In Corn Rootworm Resistance Renews Interest

This is perhaps only the latest example in a long line of examples of how nature will not remain static.

Corn rootworm resistance to one certain event was documented in Iowa and parts of Illinois last summer. It has not yet been documented in Indiana. That plus the advance of Goss's Wilt has more people wondering about the power of organisms, whether they are insects, diseases or weeds, to adapt to their environment and change, or mutate, into forms that can overcome resistance to traits that are supposed to stop them.

The Goss's wilt situation may be different. Purdue University plant pathologists still believe it's a case of the organism riding storms into more eastern states than it normally infects last summer. They do not suspect that the disease organism has changed.

The bacteria that causes it was first identified in Indiana in northwestern Indiana a few years ago. It has not spread to other areas of the state. However, some aren't yet willing to say that it's virulence the past season in neighboring states just to the west was all do to a perfect storm of environmental conditions.

Starting in January, Dave Nanda, crops consultant, who writes the Breeder's Journal column in Farm Progress magazines, including Indiana Prairie Farmer, will begin a series looking at examples of how organisms have mutated to overcome obstacles man put in their way before. He will first discuss diseases, then later weeds and insects.

"Nature does not like uniformity, and it doesn't not like a vacuum," Nanda says. He's also director of genetics and technology for Seed Consultants, Inc. "Instead nature prefers diversity. There is change going on all the time beneath the surface."

Many changes occur because cells in these organisms mutate during cell division. Most of the mutations are bad for the organism, and are discarded. However, some mutations that don't hurt the organism are retained and passed on to the next generation. Eventually, that's how a disease that once couldn't attack a certain type of corn can later attack it.

Nanda will use the classic example of southern corn leaf blight that nearly wiped out the Midwestern corn crop in the 1969 and 1970 as an example of a mutation in an organism, which then found a uniform, susceptible host set up by man's action, and back-to-back weather years that gave it the environment it needed to flourish.

If you don't remember why seed corn companies went back to detasseling corn, even though it's an expensive process, you should find his January column interesting reading. 
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