The N.C. Department of Agriculture and Consumer Services is warning sweet potato growers about an emerging root-knot nematode, Meloidogyne enterolobii, which has been identified in fields in Columbus, Johnston, Wayne and Wilson counties.
“Finding this destructive nematode in a county in the midst of our sweet potato growing belt is worrisome, because of its potential to cause significant damage to the crop if it becomes more established,” said Agriculture Commissioner Steve Troxler. “We are the leading producer of sweet potatoes in the United States, growing more than half of the total U.S. crop. Sweet potatoes generated more than $331 million in cash receipts in 2015, so it is an important crop to our economy.”
Because no resistant varieties of sweet potatoes are available against this root-knot nematode, the use of soil fumigant before planting is recommended, said Dr. Weimin Ye, nematode assay section chief for the NCDA&CS Agronomic Services Division.
Last October, Ye, regional agronomists and extension specialists visited a farm in Johnston County to look at damage and collect samples of sweet potatoes, soybeans and weeds, including morning glory, pigweed, sicklepod and marestail. Lab results from the samples revealed high numbers of root-knot nematodes in all the samples.
“Molecular diagnosis positively identified the nematode as the pacara earpod root-knot nematode. In the U.S., this species was first reported in Florida in 2004 and only more recently in North Carolina in 2013,” Ye said. “It is considered one of the most important root-knot nematode species because of its ability to develop on many economically important crops such as tobacco, tomatoes, soybeans, potatoes, cowpeas, sweet potatoes and cotton. This nematode can have a major impact on sweet potato quality, often resulting in a total loss of the crop.”
One Johnston County farmer first noticed a small area of damage in 2015, but the problem spread to about three acres of sweet potatoes in 2016, resulting in a reported total loss of the sweet potatoes, prompting him to consult his regional agronomist and county extension specialist.
Regional agronomists are part of the Field Services Section of the department’s Agronomic Services Division. They provide advice on crop fertilization, nutrient management, lime needs, soil testing, plant tissue analysis, use of animal wastes and composts, nematode analysis, and testing of source water and nutrient solutions. To find a regional agronomist for your area, go to www.ncagr.gov.
Growers with nematode-specific concerns or questions can contact Ye at 919-733-2655 or by email at [email protected].