Improvement of Bioherbicide Strategies for Invasive Weeds in Southern Cropping Systems
Biological Control of Pests Research Unit
Project Number: 6066-22000-073-00
Start Date: Feb 06, 2011
End Date: Feb 05, 2016
The objective of the proposed research is to improve the methods of production, formulation and delivery of indigenous pathogens to safely and effectively control invasive weeds. Kudzu (Pueraria lobata var. montana) and old-world climbing fern (Lygodium microphyllum) are not well controlled by chemical herbicides and are often present in sensitive areas where herbicides may be inappropriate. Other aggressive weeds, such as marestail (Conyza canadensis) and pigweeds (Amaranthus spp.) are commonly found to be resistant to the popular herbicide, glyphosate. This research plan is designed to develop safe, affordable, and practical control strategies for these weeds using the fungal plant pathogen, Myrothecium verrucaria and combinations of M. verrucaria, other weed pathogens and compatible chemical herbicides and adjuvants.
The overall objective of this project is to develop and improve biological weed control with plant pathogens (bioherbicides). Our research will focus on the following objectives:
Objective 1: Develop safe and effective formulation, mass-production, and application technology techniques and systems to improve the bioherbicidal potential and utility of bioherbicides for controlling exotic, invasive or glyphosate-resistant weeds.
Objective 2: Bioherbicidal and integrated control of kudzu.
The research plan comprehensively addresses bioherbicide development from cost-effective production methods to exclude unwanted byproducts and; to optimize formulations of bioherbicides with respect to spore and leaf-surface hydrophobicity and maintenance of free-moisture; to deliver bioherbicides with maximum spray coverage; and post-release monitoring of the agroecosystem documenting the persistence and spread of biocontrol agents. Production methods will be monitored by liquid chromatography to detect unwanted byproducts. Plant bioassays with visual and digital disease ratings will assess the effectiveness of bioherbicide formulations. Field tests will be performed in mature, naturally-occurring kudzu stands to validate bioherbicide efficacy alongside benchmark herbicides. DNA-based species-specific markers will be identified to enable post-release monitoring of bioherbicides. A strain of the bacterial pathogen Xanthomonas campestris and reduced mycotoxin formulations of the bioherbicdal fungus Myrothecium verrucaria will be evaluated for biological control of glyphosate-resistant weeds such as marestail (Conyza campestris) and pigweeds (Amaranthus spp).