For Charles Harden of Bertie County, managing plant-parasitic nematodes is one of the biggest challenges involved in growing cucumber pickles. Insufficient treatment jeopardizes yield. Excessive treatment undercuts profits.

The N.C. Department of Agriculture and Consumer Services is conducting a field study to help Harden, and other growers like him, find a solution that is both economical and effective.

Nematodes are microscopic roundworms prevalent in the sandy soils of Eastern North Carolina. The damage they cause to roots interferes with water and nutrient uptake, increases the need for irrigation and often leads to nutrient deficiencies. Infected plants are also more vulnerable to disease and are slower to mature.

Harden started growing cucumbers for Mount Olive Pickle Co. in the fall of 2004. When he had trouble getting a good stand, he didn’t expect nematodes to be involved. When he examined the stunted plants, however, he noticed the swollen root nodules characteristic of root-knot nematodes.

“That first crop was a disaster,” Harden said.

During the 2005 growing season, Harden proceeded cautiously and treated the soil for nematodes twice—first before the spring crop and again before the fall crop. Because this double treatment was so expensive, Harden wanted to know whether it was really necessary. That fall he turned to NCDA&CS regional agronomist Wayne Nixon for advice.

“I used a conservative, blanket approach to nematode management in 2005,” said Harden. “But then I called in Wayne to take a closer look. I wanted a more scientific evaluation.

Nixon visited Harden and toured his operation. He decided that field testing was the most reliable way to answer Harden’s questions.

“The situation with cucumber pickles is unique,” Nixon said. “Growers typically harvest two or three successive plantings in a single growing season. Therefore, they actually have an opportunity to treat the soil several times in one season.”

In March 2006, Nixon collected soil samples and had them tested for nematodes. Laboratory results indicated that several fields had potentially damaging population levels. One field had a root-knot nematode population 60 times greater than the threshold level for treatment.

Nixon set up test plots on Harden’s farm to find out whether one annual treatment could be effective, especially against extremely high populations. If so, the savings could amount to as much as $200 per acre. Results so far are encouraging, if not conclusive.

Data from 2006 indicate that a single, early-spring application of Telone II (1,3-dichloropropene) at 8 to 10 gallons per acre can give good nematode control. Nixon monitored nematode populations at regular intervals and found that they remained below threshold levels throughout the growing season. Even the most heavily infested test plots did not require a second treatment before subsequent plantings.

“A yield increase of about 17 bushels per acre is necessary to make the 10-gallon-per-acre Telone treatment cost-effective,” Nixon said. “I measured increases of 12 to 44 bushels in my test plots. Yield compensated for the cost of treatment 75 percent of the time.”

Nixon is continuing his field study throughout the 2007 growing season. By this time next year, he expects to have two years of useful data on nematode population dynamics, treatment effectiveness and yield. He also plans to evaluate whether the treatments may further enhance cucumber yield or quality by controlling other crop diseases or pests.

“For pickle-cucumber producers, striking the right balance promises to be lucrative,” Nixon said. “Each planting matures in about 35 days with a potential return of $1,200 per acre. Realizing this return is tied closely to being able to achieve cost-effective nematode management. By routinely submitting samples for testing, growers know where to focus their management efforts.”

North Carolina farmers have access to one of the most comprehensive agronomic testing and advisory services in the nation. The NCDA&CS Agronomic Division laboratories perform soil tests, nematode assays, and nutrient analyses of plant tissue, composted materials, wastes, nutrient solutions and source water. Thirteen regional agronomists are available to visit growers; evaluate suspected problems, give advice on sampling, liming and fertilization, and help identify and manage nematode problems. Visit the Agronomic Division’s Field Services Section online at www.ncagr.com/agronomi/rahome.htm for contact information.

Agronomist Wayne Nixon is available to provide advice on fertilization, nutrient management and nematode problems in Bertie, Camden, Chowan, Currituck, Gates, Hertford, Pasquotank and Perquimans counties. He can be reached by phone at (252) 426-7210 or by e-mail at wayne.nixon@ncagr.gov.