Agronomic Services — News ReleaseFOR IMMEDIATE RELEASE
THURSDAY, OCTOBER 25, 2006
Contact: Rick Morris, Regional Agronomist
NCDA&CS Agronomic Division
Poor corn yields? Check for nematodes.
BLADENBORO—Spring has been cool and wet in southeastern North Carolina. In some areas, 10 to 13 inches of rain have fallen during the last month. Under these circumstances, the N.C. Department of Agriculture and Consumer Services' Agronomic Division wants to remind corn growers that agronomic testing can be beneficial.
Corn growth got off to a slow start this spring in many areas of eastern North Carolina. Although cool temperatures were probably a factor, recent findings by the N.C. Dept. of Agriculture and Consumer Services show that plant-parasitic nematodes played an important role in some corn fields this year. For this reason, NCDA&CS is reminding growers that the best time to take soil samples for nematode assay is right now-as soon after harvest as possible.
Dan Ward of Clarkton has already sent in his samples for nematode assay. Ward has grown peanuts, tobacco, soybeans and corn his whole life. He manages nematode problems on most of his crops but had never seen the need to do so for corn. This year changed his mind.
"I planted about 1300 acres of corn this spring," said Ward. "In May, I had stunted, yellow plants on nearly 40 acres of one large field that had been in corn last year and done well. Right away, I starting checking out the problem."
NCDA&CS regional agronomist Rick Morris came out to look at Ward's field. He helped him take diagnostic soil, nematode and plant tissue samples. Test results indicated that the crop was low in potassium and marginally low in sulfur and copper-results easily explainable by the high populations of stubby root nematodes in the soil.
Plant-parasitic nematodes damage roots and interfere with uptake of nutrients. Often, nutrient deficiencies are the earliest sign of a nematode problem. Although it was too late to manage the nematodes in Ward's field, Morris decided to monitor the crop throughout the season to document the damage.
When the field was harvested on September 18th, the results were dramatic. Jeff Bridges kept an eye on the yield monitor as he maneuvered the combine. Readings ranged from 140 to 175 bushels per acre in good areas of the field and plummeted to 0 to 30 bushels in nematode-infested areas.
"Seed costs $140 per bag, and I plant 27,500 seed per acre," said Ward. "I can't afford to put that much money into seed to get this kind of result. I will definitely be on the lookout for nematode problems in corn from now on."
Many N.C. corn growers have come to expect low yields and often blame the weather. The situation in Ward's field, however, shows that low corn yields may have an easily diagnosable and somewhat manageable cause-nematodes. These pests abound in the soils of eastern North Carolina. A few samples and an inexpensive nematode assay can identify potential problems and help growers choose the least hazardous fields for their crop.
"As prevalent as nematode problems have been this year, I would advise all corn growers to collect samples for nematode assay," said Morris. "It's convenient to collect these samples after harvest because that's when routine soil samples are also normally collected. Just divide the soil sample in half and send part of the soil for nutrient analysis and part for nematode assay. It only takes about ten minutes more, but you get twice as much information."
Samples taken soon after harvest give the best picture of the nematode situation. As time elapses between harvest and sampling, samples will be less and less likely to indicate the true seriousness of a nematode problem. Cool weather and removal of the host crop will naturally cause nematode populations to decline, and it will be more difficult to detect hazards for the next crop.
NCDA&CS nematode assays cost $3 each for in-state samples. Processing takes about two weeks. Reports are posted online and a copy is mailed to the grower. Growers from other states who are interested in using North Carolina's nematode assay service should call the Agronomic Division office in Raleigh for fee information and other details.
Nematode assay sampling supplies-instructions, plastic bags and boxes, and sample information forms-are available at the Division office in Raleigh and at all N.C. Cooperative Extension offices. Sampling instructions and information forms are also available online at www.ncagr.com/agronomi. For additional assistance, call the Division office at (919) 733-2655 or contact your NCDA&CS regional agronomist.