2012 Annual Report
1a.Objectives (from AD-416):
1. Identify and characterize nematode resistance genes and improve host-plant resistance to nematodes in cotton and peanut.
1.a. Characterize and improve resistance to root-knot and reniform nematodes in cotton.
1.b. Identify resistance/susceptibility to the lesion nematode in peanut.
2. Develop integrated strategies and control options for managing nematodes in cotton and peanut.
2.a. Enhance the efficacy and consistency of biological control of nematodes.
2.b. Identify new cultural control options for managing nematodes in cotton and peanut.
2.c. Develop integrated approaches for managing nematodes.
1b.Approach (from AD-416):
Field and greenhouse experiments will be conducted to improve management of plant-parasitic nematodes in cotton and peanut. Host-plant resistance to nematodes is the cornerstone of our nematode management strategy. We will work cooperatively with plant breeders to develop cultivars and germplasm with desirable agronomic traits and a high level of nematode resistance. Plant material will be selected for resistance using traditional and marker-assisted selection. However, we cannot rely exclusively on host-plant resistance for managing nematodes. We will also investigate ecologically-based control strategies that can be integrated with resistant cultivars to increase the durability of resistance and control a broader spectrum of nematode pathogens. Biological control organisms are being marketed for use in cotton and peanut, and also occur naturally in fields. We will explore the effect of crop production practices (tillage, fumigation, cultivar, and cover crops) on these antagonistic organisms with the goal of conserving or enhancing their activity against nematodes. We will identify crops that can be grown in rotation with cotton and peanut that will reduce populations of root-knot nematode either by producing toxic metabolites (high residue rye) or by limiting nematode reproduction (sorghum for bioenergy use). Our integrated management approach will also include increasing plant tolerance to nematode damage by applying cytokinin to seedlings. Finally, we will combine the most effective and economical control options from earlier years of the project to test different integrated management programs for plant-parasitic nematodes in the southeastern United States.
This report documents progress for Project Number 6602-21220-015-00D, which started April 9, 2012 and is the replacement project for 6602-21220-013-00D.
A field study is underway to evaluate the influence of tillage and fumigation with 1,3-dichloropropene on abundance of the nematode parasite Pasteuria penetrans. We have collected soil from this field site and determined the abundance of P. penetrans spores in the different treatments. We have also set up a greenhouse study to determine reproductive potential of the southern root-knot nematode in the different treatments. This is the first of a multi-year study.
We completed two greenhouse trials to determine the efficacy of Paecilomyces lilacinus (a fungal pathogen of nematodes marketed as NemOut) on different crop plants. The greatest percentage suppression of root-knot nematodes by the fungus was in peanut (67%) and the lowest was in corn (26%); suppression in cotton was intermediate (40%). In another greenhouse experiment, we found that suppression of root-knot nematodes in cotton by P. lilacinus was enhanced when a rye cover crop was grown before planting cotton. The rye was grown for a month and then killed with a herbicide before P. lilacinus was applied along with a cotton seed to the soil. In two trials of this experiment, nematode suppression by the fungus averaged 36% in fallow soil and 63% in soil that had a rye cover crop. One additional trial of the cover crop experiment is needed before the results can be published.
Preliminary greenhouse tests were completed on 82 sorghum entries evaluating their suitability as a host for Meloidogyne incognita, the cotton root-knot nematode. We documented widely varying levels of nematode reproduction ranging from 0 to 379% of the eggs per plant measured on corn, a susceptible plant used as a standard for comparison. Approximately a third of the entries tested had a high level of resistance and should be a useful genetic resource for sorghum breeders. Field tests have been initiated to determine how much damage the nematodes cause to susceptible entries.