Robert Carver, Mcgawley, Edward C.
INVESTIGATOR: McGawley, E. C.
Plant Pathology & Crop Physiol
LOUISIANA STATE UNIVERSITY
BATON ROUGE, LOUISIANA 70893
IDENTIFICATION, BIOLOGY, AND MANAGEMENT OF AGRICULTURALLY IMPORTANT PLANT PARASITIC NEMATODES
CLASSIFICATION HEADINGS: R212 . Pathogens and Nematodes Affecting Plants; S1122 . Strawberry; F1120 . Nematology; R216 . Integrated Pest Management Systems; S1460 . Tomato; S1411 . Beans (fresh, fresh-processed); S1530 . Rice; S1710 . Upland cotton; S1820 . Soybean; S2020 . Sugar cane; S3130 . Nematodes
NON-TECHNICAL SUMMARY: Plant parasitic nematodes are a serious, ever-present and insidious agricultural production constraint. They are the most biologically complex of the classical plant pathogen types. They are frequently overlooked because most reside in the soil as root parasites and the damage they cause is frequently attributed to non-biological entities such as waterlogging, drought or nutrient deficiencies or toxicity. By virtue of their metabolic complexity, the chemicals used to manage them have historically been the most toxic. The environmental consequences of overuse and mishandling of many of these chemicals have resulted in their ban by the U.S. EPA in recent years. In the near future, a majority of the remaining nematicide arsenal will likely be banned. It is for this reason that we are allocating a significant portion of our activities toward the identification of new materials and organisms which can efficiently manage/suppress nematode pathogens with minimal environmental consequences.
OBJECTIVES: (1) To identify genera, species, and races of plant-parasitic nematodes that impact crop species important in agriculture in Louisiana. (2) To evaluate the interrelationship of plant-parasitic nematodes with other organisms present in agricultural production systems in Louisiana. (3) To evaluate environmentally responsible management tactics useful in minimizing nematode-related crop losses.
APPROACH: The maintenance of a current census of nematode genera, species, and pathotypes associated with the major crop commodities of Louisiana is one of three objectives of this project. Soil and root samples representative of the major crops and production areas in the state are collected. Laboratory activities include extraction and microscopic enumeration for generic identification. Known damaging genera are further identified by being subjected to electrophoretic analysis of macerated preparations of the females that produce diagnostic banding patterns on acrylamide gel. Other genera which require speciation are subjected to greenhouse-based host range assays. The second project objective, to evaluate the interrelationship of plant-parasitic nematodes with other organisms present in agricultural production systems in Louisiana, is addressed primarily by using microplot (autoclaved terra cotta containers [arranged in an outside, covered environment] containing "biologically clean" soil which is infested with known pathogen or pathogen/pesticide combinations)based methodology. This protocol, which mimics a production environment, allows precise manipulation of pathogen population combinations and/or chemicals being evaluated for their management. The third objective of this project is to evaluate environmentally responsible management tactics useful in minimizing nematode-related losses. Currently this research is focused primarily on the identification and evaluation of new, low-rate, chemical nematicides. Studies will involve field plot and microplot evaluations of two colloid-based materials, one biological agent and leachates collected from three weed species common in Louisiana. Results of this research are presented first-hand to producer groups and forwarded to our extension nematologist for further dissemination. Research data from all of these studies is subjected to appropriate scientific data analysis protocols and summarized in an annual report.
KEYWORDS: nematode pathogens, nematode management, novel management techniques,; nematode pathotypes, nematode complexes
PROGRESS: 2010/01 TO 2010/12
OUTPUTS: Research describing the existence of virulence phenotypes of the reniform nematode, Rotylenchulus reniformis, on cotton was published. In two other publications, research on the use of site-specific management practices for reniform nematode was outlined. A multimedia presentation entitled "Introduction to Nematodes" was released via the internet site of the Organization of Nematologists of Tropical America (ontaweb.org) in 2010. During this reporting period, a graduate-level class in nematology was taught. National and international plant pathology and nematology meetings, at which multiple research and teaching presentations were made, were also attended. PARTICIPANTS: Drs. Charles Overstreet and Michael J. Pontif are collaborators on this project. TARGET AUDIENCES: Target audiences are plant breeders, soybean and cotton producers and plant protection scientists. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
IMPACT: 2010/01 TO 2010/12
The "Introduction to Nematodes" presentation has had over 1,000 downloads to date and has received favorable reviews on the websites of the European Society of Nematologists, The Mediterranean Society of Plant Pathology and the International Federation of Nematology Societies. Data generated by this project strongly support the hypothesis that virulence phenotypes of Rotylenchulus reniformis exist in the southern United States. This research is the first in the United States to clearly document this difference in pathogenicity among geographic isolates of the nematode and partially accounts for the difficulty in producing resistant cotton germplasm.
PUBLICATIONS (not previously reported): 2010/01 TO 2010/12
1. McGawley, E. C., M. J. Pontif, and C. Overstreet. 2010. Variation in reproduction and pathogenicity of geographic Isolates of Rotylenchulus reniformis on cotton. Nematropica 40:275-288.
2. McGawley, E. C., M. J. Pontif, and C. Overstreet. 2010. Introduction to Nematodes: a Multimedia presentation.
3. Overstreet, C., E.C. McGawley, E. Burris, D. Burns, B. Padgett and R.L. Frazier. 2010. Site-specific management strategies used in Louisiana. Pg. 52-59 In: Proceedings of the Beltwide Cotton Conferences, New Orleans, LA.
4. Overstreet, C., E. C. McGawley, M. Wolcott, D. Burns, E. Burris, and G. B. Padgett. 2010. Using verification strips to define nematicide response areas to the Southern root-knot and reniform nematodes in cotton in the Alluvial soils of the mid-South, USA. Pg. 144. In: Proceedings of the 3rd Conference on Precision Crop Protection. Bonn, Germany.
Name: McGawley, E. C.