Duration: 10/01/2007 to 09/30/2012

Administrative Advisor(s):

NIFA Reps:

Non-Technical Summary

Statement of Issues and Justification

Significant needs exist in agricultural, horticultural, urban and natural systems for improved integrated weed management strategies. In agriculture, consolidation of agrochemicals companies has resulted in reduced registrations for new herbicides, and herbicide resistance and other factors have resulted in declining efficacy in existing herbicides. In horticulture, herbicide registrations are increasingly limited in many crops, and growers continue to transition into organic production. In urban and natural systems, many weeds are poorly controlled and target specific products are largely unavailable. Bioherbicide technology continues to offer opportunities for improving weed management in each of these systems.

The Southern Region Multistate Project S-1001 Development of Plant Pathogens as Bioherbicides for Weed Control (2001-2006) (and its preceding projects) has been an important focus for the coordination of bioherbicides research in the USA and internationally. In the last 5-10 years, the activities of participants in S-1001 have become increasingly diverse. Research towards the development of host-specific fungal plant pathogens has continued, and participants have become increasingly involved in investigations of broad host-range pathogens, phytotoxins, microbial weed seed decay, virulence enhancement and a range of other topics allied to biological weed management and the development of bioherbicides. Thus, the bioherbicides community has changed, involving an increasingly broad range of scientific disciplines, and the role of S-1001 has evolved. We propose to renew the S-1001 Regional Project, in 2006, as a Coordinating Committee. This will enable the group to maintain its structure (web page, annual symposium meeting etc.) which has served well to coordinate research and exchange ideas in the field. In the absence of this Coordinating Committee, significant opportunities to exchange ideas among like-minded scientists would be lost. This is particularly important at present as new technologies are becoming available that can be applied in a number of different labs studying analogous systems.

Objectives

Procedures and Activities

Objective 1. Integration of bioherbicides into weed management systems.
Considerable research in recent years has considered strategies for the integration of bioherbicides into cropping systems, and a number of important questions will continue to be addressed:
1) How can host-specific bioherbicides be integrated into cropping systems where multiple weeds require control? Key opportunities exist in systems such as midwestern corn and soybean production where herbicide resistant common waterhemp (Amaranthus rudis) often emerges as a single-species problem following poor herbicide efficacy. Likewise, in glyphosate resistant crops, some weeds, such as morningglories that are relatively tolerant to glyphosate, are increasingly escaping control. Methods used include the testing of the direct interactions among bioherbicides and chemical herbicides, testing in field plots with custom-designed pesticide regimes, and on-farm experiments, where bioherbicides are integrated into current farmer practices.
2) How can bioherbicides be integrated into cropping systems where fungicides (and other fungitoxic compounds) are used? There is a key need to understand the potential problems with the application of bioherbicides (especially where live organisms are deployed) where antagonistic chemicals are also used. Particular issues exist in horticultural and nursery crops where fungicide applications may be routine. In this case, the modeling of application windows where bioherbicides can effectively be deployed must be determined,
3) How can bioherbicides be integrated into non-conventional systems? Organic producers, especially those operating on a small scale, may have limited access to equipment. Control in turfgrass systems may have specific needs, such as to educate home owners in the application of novel products. Control of invasive plants in environmentally sensitive natural systems where access may be problematic may require specific integration strategies. In developing countries where production facilities, distribution networks and storage conditions may be limiting and where farmers may have limited experience with weed management inputs considerations of the integration of bioherbicides in a realistic socio-economic context will continue to be paramount.
The group as a whole has enormous experience with all of these problems, with its members operating in very diverse systems. The committee will coordinate the transfer of knowledge from different groups that are examining varied bioherbicide integration strategies. Objective 2. Virulence enhancement and environmental tolerance-enhancement of bioherbicides.
Two key strategies for virulence enhancement have been discussed in great detail by the S-1001 group in the last five years. Firstly, the amino-acid excretor model developed by D. Sands and A. Pilgeram has been tested by a number of groups, and can be extended to additional groups through the coordinating committee. In this approach, amino acid regulation in the plant is suppressed by short-circuiting its feedback control by inoculating the plant with an amino acid-excreting strain of a plant pathogen. Further testing will determine the degree to which this may apply to multiple systems. A second approach much discussed by the S-1001 group facilitated by J. Gressel following his experiments with Fusarium spp. and C. coccodes is to generate transgenic bioherbicides. As a group, we have much to learn from further experiments testing the opportunities for incorporating genes into bioherbicides, including "soft" genes that may regulate the production of products such as plant hormones and "hard" genes that may permit the bioherbicide to release novel toxins. The group is studying a range of different organisms that might serve as valuable donors of interesting genes (e.g. Myrothecium verrucaria produces an array of phytotoxins, Pseudomonas syringae produces tagtoxin) and valuable recipients of genes (e.g. Fusarium oxysporum has a high degree of rhizosphere competence and one could envisage an engineered isolate persisting in the root zone releasing herbicidal molecules).
Objective 2. Virulence enhancement and environmental tolerance-enhancement of bioherbicides.
Two key strategies for virulence enhancement have been discussed in great detail by the S-1001 group in the last five years. Firstly, the "amino-acid excretor" model developed by D. Sands and A. Pilgeram has been tested by a number of groups, and can be extended to further groups through the coordinating committee. In this approach, amino acid regulation in the plant is suppressed by short-circuiting its feedback control by inoculating the plant with an amino acid-excreting strain of a plant pathogen. Further testing will determine the degree to which this may apply to multiple systems. A second approach much discussed by the S-1001 group facilitated by J. Gressel following his experiments with Fusarium spp. and C. coccodes is to generate transgenic bioherbicides. As a group, we have much to learn from further experiments testing the opportunities for incorporating genes into bioherbicides, including "soft" genes that may regulate the production of products such as plant hormones and "hard" genes that may permit the bioherbicide to release novel toxins. The group is studying a range of different organisms that might serve as valuable donors of interesting genes (e.g. Myrothecium verrucaria produces an array of phytotoxins, Pseudomonas syringae produces tagtoxin) and valuable recipients of genes (e.g. Fusarium oxysporum has a high degree of rhizosphere competence and one could envisage an engineered isolate persisting in the root zone releasing herbicidal molecules).
Objective 3. Production, formulation and application strategies.
The coordinating committee has a key role to play in this area, since all bioherbicide researchers are involved, to a greater or lesser degree, in all of these areas. For the most part, however, production, formulation and application strategies are developed specifically for on-going projects, generally with a view only towards the performance of effective field trials, and few bioherbicides have been followed through to full commercial scale-up. There is a danger that knowledge in these areas will remain isolated. The coordinating committee will serve as an important forum for the discussion of different groups' approaches to production, formulation and application, and effective strategies will continue to emerge.
Objective 4. Managing cropping systems to support weed suppressive microbes; Conservation Biological Control.
This area of research has been a relatively minor component of the S-1001 group's efforts, with the obvious exception of the work of R. Kremer's group, in the last two decades. Recently, however, a number of participants have undertaken studies that examine the role of microbes in weed population demography, and have examined the role of crop management perturbations upon microbial communities and their concomitant impacts on weeds. These studies will also lead to the discovery of additional soil borne microbes that can be developed as bioherbicides. These contributions will continue to strengthen the group's understanding of the ecology of weed-microbe interactions.

Expected Outcomes and Impacts

Projected Participation

View Appendix E: Participation

Educational Plan

Although this project does not have a specific extension/outreach component, a key role of this group is to foster the development of the field, especially the development of young scientists. Information developed in this project will be disseminated to stakeholders and scientific audiences through refereed journal articles, conference abstracts, extension bulletins and field demonstrations, and through our annual meetings and reports. The project will continue to maintain its web page which will be updated by the Chair of the committee. Successful bioherbicides will be made available through cooperating state and federal agencies.

Organization/Governance

Organizational objectives will continue to be met as in previous years, and a standard for Southern Coordinating Committees. A Secretary and Chair will be selected by the membership at annual meetings, serving for a five year term. The secretary will have the principal duty of organizing the annual meeting (venue logistics, minutes, etc.) and will act as treasurer. The chair will have the principal duty of coordinating the agenda for the annual meeting, facilitating the annual meeting, maintenance of the web page, and for reporting.

Literature Cited

Attachments

Land Grant Participating States/Institutions

AR, CT, IN, MT, NC, NY, PA

Non Land Grant Participating States/Institutions

Novozymes Biologicals, USDA-ARS Beltsville Agricultural Resarch Center, USDA-ARS/Florida