Charles Overstreet, Merrill, Thomas A. | 4/22/2005 11:34:22 PM
With planting season for corn approaching, LSU AgCenter expert Dr. Charles Overstreet says the crop may be an excellent option for those who need to manage reniform nematodes.
Overstreet said the growing conditions last summer resulted in extremely high populations of this pest and that soil samples this fall showed high levels of nematodes in many fields. Worse yet, the mild winter means growers can expect many of the pests to survive – which would mean problems for a cotton crop, he said.
"Although corn is not damaged by reniform nematode, cotton, which is often rotated with corn, certainly is," explained Overstreet, who is a professor in the LSU AgCenter’s Department of Plant Pathology and Crop Physiology.
That’s why the LSU AgCenter expert says planting corn this year in fields where nematodes could be a problem may be the best option.
"Because corn is a very poor host – or no host at all – for the reniform nematode, you are essentially starving them to death," Overstreet said, adding, however, "Unfortunately, these are very tough and persistent pests."
The LSU AgCenter expert said planting corn in a field one year can knock back reniform nematode populations 50 percent to 60 percent, but it often takes the second year in corn to really reduce the numbers by more than 80 percent.
"The rotation time that you need to use corn depends on the severity of the reniform nematode problem and whether or not you can stand to have corn on cotton ground for that long," Overstreet said. "One year in corn often will bring nematode populations back to a level where they can be successfully managed with a nematicide when cotton is planted."
Although corn will not support nematode development, some of the weeds that are present in a corn field will, according to Overstreet.
"It’s not known at this time just how much of an influence these weeds have on late-season population development of the reniform nematode," he said, adding, "Broad weeds are much more likely to be hosts than grasses."
Overstreet said a good weed control program during the growing season of corn should give the maximum benefits of using corn to reduce nematode numbers.
"The use of cotton continuously certainly can lead to serious problems with the reniform nematode," Overstreet cautioned. "This nematode has incredible abilities to reproduce and will build up to extremely high numbers in the soil on susceptible crops like cotton.
"Corn can help break the life cycle of reniform nematode, and that helps bring them back to manageable levels."
The LSU AgCenter expert said a good rule to remember about using corn for reniform nematode management is that one year is good, but two years are better.