Name: Dr. W. Carroll Johnson, III

Title: Research Agronomist, Weed Science

Research: Basic and applied research on the ecology and integrated control of weeds in peanut, vegetables, and related cropping systems.

Support Staff: Andy Hornbuckle and Dan Evarts

Address: Crop Protection and Management Research Unit
USDA-ARS, Crop and Soil Sciences
P.O. Box 748
Tifton, GA 31793-0748

Phone: 229-386-3172

FAX: 229-386-3437

E-Mail: CJohnson@tifton.usda.gov

Education: B.S., Auburn University, Entomology
M.S., North Carolina State University, Weed Science
Ph.D., North Carolina State University, Weed Science

CRIS Project Title: Integrated Management and Ecology of Weed Populations in the Southeastern Coastal Plain

Research Goals: Develop alternative weed and crop management systems for selected agronomic and vegetable crops grown in the Southeastern Coastal Plain, with emphasis on integrating alternative cultural and tillage practices for weed control which reduce dependence on herbicides.

Conduct basic research in weed-crop ecology in irrigated and reduced tillage systems for agronomic and vegetable crops grown in the Southeastern Coastal Plain.

Major Accomplishments:

Developed the stale seedbed system for peanut and vegetable production that reduces total weed management costs by as much as 50%. The system uses a precisely timed shallow seedbed tillage prior to planting which depletes weed seed in the soil plow layer, thus reducing troublesome weed problems.

Developed a system of weed management in transplanted cucurbits grown on plastic-covered beds. Plastic-covered beds are an effective cultural weed control practice, and when integrated with judicious herbicide use and newly discovered alternatives to methyl bromide, effectively manage weed and other soil-borne pests.

Discovered that peanut planted in a narrow row pattern can reduce herbicide use and improve weed management efficiency without increasing peanut planting rates or other production costs

Discovered that weeds are important hosts for tomato spotted wilt virus (TSWV), a serious viral disease of peanut, vegetables and tobacco grown in the Southeast. This research was critical in the development of an integrated approach to management of TWSV.

Quantified the effects of nutsedge on peanut yield. Peanut is an efficient competitor with yellow nutsedge, but yield is reduced by approximately 50 lbs for every nutsedge plant/m2 that competes full-season.

Identified the functional relationship between yield of cucumber and yellow nutsedge density. Results showed that cucumber is an effective competitor with yellow nutsedge, provided that cucumber is planted at an optimal density to produce a uniform stand.

Discovered that peanut is highly susceptible to arsenic accumulation in kernels due to either drift or non-registered applications of low rates of the cotton herbicide MSMA (monosodium methanearsonate). These findings were used to educate growers in the Southeast to show that the nonregistered use of MSMA on peanut resulted kernels contaminated with arsenic which made them unmarketable.

Designed and developed a modified power-tiller to apply metham for weed control in transplanted cucurbit crops or plastic-covered beds. Metham applied with this tiller controls yellow nutsedge.

Developed an innovative procedure to accurately quantify herbicide effects on peanut. This procedure was used to evaluate preemergence application of dinitroanaline herbicides which is less costly and provides more consistent weed control than conventional preplant incorporated application of herbicides.

Developed a technique to control late-season tall weeds using paraquat applied with a wick-bar. The technique removes tall weeds that interfere with fungicide applications for leafspot control or with peanut harvest.

Discovered that metham followed by 1,3-D plus chloropicrin is an efficacious, cost-effective alternative to methyl bromide in vegetable crop production. The combination of metham followed by 1,3-D plus chloropicrin was more consistent, controlled a broader spectrum of weeds, and was 43% cheaper than methyl bromide.

Documented the benefits of crop rotation in the suppression of yellow nutsedge, one of the most difficult weeds to control in the Southeast. This research showed that properly managed crops in a peanut-cotton-corn rotation effectively suppresses yellow nutsedge without additional herbicide inputs.

List of Publications
Weed Science Information Page