My assignment is to find better ways to manage nematode pests in cotton production systems. Most work is on the nematodes Meloidogyne incognita and Rotylenchulus reniformis, and focuses on nematode resistance in cotton and the use of nematode attractants and repellents as management tools.

The cotton germplasm research is being done in collaboration with other labs. In collaboration with United Ag Products, we are investigating the inheritance and expression of multiple sources of nematode resistance in cotton; we hope to find gene combinations that can be pyramided to achieve reniform nematode resistance, which is currently lacking altogether in Upland cotton. In another project, in collaboration with the Curator of the National Cotton Germplasm Collection, we are trying to find sources for reniform nematode resistance among more than 2,000 race stocks of cotton collected from around the world. Genetic engineering of nematode resistant cotton is being attempted with the USDA molecular biology at Lubbock, TX. Currently we are examining gene constructs designed to prevent or disrupt the nurse cells that are formed by roots in response to nematode feeding. In collaboration with the Crop Biotechnology Center of Texas A&M University, we are trying to find molecular markers for naturally occurring nematode resistance genes, that cotton breeders can use to develop resistant cultivars.

A separate project on nematode behavior is targeted toward modifying the composition or placement of granular nematicides, fertilizer components, and limestone to create gradients of carbon dioxide (which is strongly attractive) and nitrogenous salts (which are repellent) or other behaviorally active substances within the soil to induce nematodes to accumulate around granules releasing conventional or novel nematicides or encapsulated nematophagous fungi. So far we have characterized effects of natural soil temperature gradients on nematode movement, measured the magnitudes of gas gradients and the gas release rates needed to attract infective stages of nematodes to point sources of CO2 in the soil, utilized CO2 to induce movement into regions of the soil where alginate pellets containing selected nematophagous fungi (Monacrosporium cionopagum, M. ellipsosporum, and Hirsutella rhossiliensis ) have been placed, examined responses to various salt gradients, and developed techniques for simulating foci of alcoholic fermentation within the soil.