Name: Richard F. Davis

Title: Research Plant Pathologist (Nematology)

Research: Management of plant-parasitic nematodes in agronomic and vegetable crops, with special emphasis on cotton. Research includes developing and utilizing nematode resistant crop plants and evaluating the effects of crop rotations and cultural practices on crop production.

Support Staff: Tommy Hilton and Kyle Montfort

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

Phone: 229-386-3159

Fax: 229-386-3437

E-mail: rfdavis@tifton.usda.gov

Education: B.S. in Integrated Pest Management, Auburn University, Auburn, AL
M.S. in Plant Pathology, Auburn University, Auburn, AL
Ph.D. in Plant Pathology, University of Illinois, Urbana, IL

CRIS Project Title: Management of plant-parasitic nematodes in agronomic, vegetable, and forage crops grown in the Southeast

Research Goals: To develop nematode management options in agronomic and vegetable crops that maximize profitability. Current research includes development of root-knot nematode resistant cotton cultivars and corn germplasm; determining the most effective way to integrate nematode-resistant cotton and pepper cultivars into crop production systems; investigating the effects of crop rotations, winter cover crops, and cultural practices on nematode management in cotton and pepper; and investigating the interaction between root-knot nematode stress and drought stress in cotton.

Major Accomplishments: In a collaborative project with Dr. Lloyd May, University of Georgia cotton breeder, significant progress has been made in the development of root-knot resistant cotton. So far, two moderately resistant germplasm lines have been released, and we have created advanced backcrosses that have retained a high level of resistance. This work should produce the first highly nematode-resistant cotton cultivar with high yield and fiber quality. In a related project with Dr. Peng Chee, University of Georgia molecular plant breeder, we are developing molecular markers for root-knot nematode resistance genes in cotton.

Documented that irrigated corn is an effective and economically acceptable rotation crop for the management of the reniform nematode in cotton. Also documented that reniform-resistant soybean is effective but not economically acceptable in Georgia. Showed that reniform nematode population levels rebound quickly following suppression with crop rotation, so the beneficial effect will only last one growing season.

Documented that the corn hybrids currently grown in Georgia are all good hosts for the southern root-knot nematode, which means that corn is a poor rotation crop for cotton when this nematode is present.

Showed for the first time that moderate root-knot nematode resistance is correlated with nematode tolerance in cotton. Resistance refers to the plant's effect on the nematode's ability to reproduce and tolerance refers to the nematode's effect on the plant's ability to produce a crop (tolerant plants produce nearly normal yields even when nematode pressure is high). This is important because it shows that incorporating moderate resistance into cotton will increase yields as well as suppress nematode populations.

Documented that three species of root-knot nematodes were capable of significant reproduction on yellow Granex onion (such as Vidalia onions). Transplanted onions did not suffer reductions in yield or economic return, but direct-seeded onions did. Transplanting onions is expensive and there is interest among growers in reducing costs by direct seeding. This work shows that nematodes are not a significant concern now, but nematode management will have to be addressed if growers begin direct seeding their onions.

In collaboration with Dr. Patricia Timper, USDA-ARS Plant Pathologist (nematology), we documented in greenhouse studies that some winter cover crops are very good hosts for the southern root-knot nematode whereas some cover crops are poor hosts. Winter soil temperatures in south Georgia are usually sufficient to allow nematode reproduction, and field tests verified that cover crops which are good hosts can increase nematode population levels in the field thereby leading to increased damage in a following cotton crop. This is important where the nematode is present because it shows that nematode-resistant cover crops should be chosen to prevent increasing nematode problems in a field.