Objective:
To develop microbial herbicides to control important agricultural and invasive weeds and ecologically based weed management strategies for sustainable and organic production systems.

Approach:
A world collection of Pseudomonas syringae pv. tagetis will be screened for biological activity on Cirsium arvense to select the most efficacious strain. Molecular techniques will be used to enhance the biological activity of selected microbial biological control agents. The role of tagetitoxin in the biological activity of P. syringae pv. tagetis will be determined. A combination of descriptive research to define the impact of long-term cropping systems and component research to identify superior crop cultivars and cover crop management systems will be used to improve weed management systems. The resources of three long-term cropping systems experiments will be used to explore the influence of conventional and organic cropping systems on weed population dynamics. The influence of cover crop residue decomposition and its interactions with soil properties and seed depth on weed seedling recruitment will be determined.