Root knot nematodes can be a significant economic problem for cotton growers. The dilemma is cost – a grower needs to spend upwards of $35 per acre to control the pest each year, making entire field applications impractical. On the other side, soil sampling to get more precise about applications costs about $25 per sample for a single nematode assay, another untenable number for the grower.
Dr. Ed Barnes, associate director, agricultural research at Cotton Incorporated, in cooperation with Dr. Bob Nichols, also in the ag research division, are applying their respective expertise to solve this economic and agronomic conundrum. “Bob knows nematodes, and I know precision technologies, so it’s definitely been a cooperative effort,” notes Barnes.
What is known about the nematode is that it favors sandy soil. So, researchers at the Louisiana State University, the University of Georgia at Tifton, and the University of Arkansas have been working to exploit this tendency using soil conductivity mapping. Soil conductivity analysis such as that generated by systems manufactured by Veris Technologies (as well as others) can, with a single pass over the field, create a soil-type map that includes an indication of sandy areas. Using the soil type map, researchers can overlay the information with a yield map or normalized difference vegetation index (NDVI) image map and line up sandy soil areas with sections of poor yield performance. “What researchers have been finding is that if you have a high sand content and low yield, and you know there is root knot nematode in the area, you can start mapping out your root knot nematode infestations with very little soil sampling,” explains Barnes.
“What we have now are some tools to do site-specific application of nematicides,” he adds. “At the sites we work in Georgia and Louisiana, and other areas as well, there is a lot of evidence that soil conductivity highly correlates to sand content.”
