Managing field borders for weed seed predators

Managing field borders for weed seed predators

Summary

Weed seed predation could be part of an alternative weed management program for organic growers if weed seed eating organisms can be conserved and enhanced. Field border management that increases vegetative diversity is a potential method for conserving weed seed predators.
Predator exclusion cage studies conducted in the fall of 2010 showed that field border management has little effect on weed seed predation within the crop field. Preliminary data analysis found, however, that crop type heavily influences seed predation rates within the field.

Objectives/Performance Targets

1.) Determine the effects four different field border vegetation communities have on levels of weed seed predation in adjacent crop fields by invertebrates and vertebrates.
2.) Identify the specific predators responsible for this weed seed predation.
3.) Disseminate the results of this project to organic growers.

Accomplishments/Milestones

Predator exclusion cage studies conducted in September, October, and November (2010) showed that field border management has little influence on weed seed predation in the adjacent crop field.
Weed seed predation seems to increase as annual grass seed volume increases in the field borders. However, this effect is only evident at the field/border interface and does not extend into the field. Weed seed predation in the crop field was heavily influenced by crop species and probably relates to canopy cover. Fields with high canopy cover crops (e.g. hay fields) experienced greater weed seed predation than fields with low canopy cover crops (e.g. harvested corn fields).

By testing different cameras we found video monitoring equipment that can sufficiently record the movements of small insects and larger weed seed predators. These cameras will be deployed in the fall of 2011.

Preliminary results were reported at the Annual Meeting of the Entomological Society of America. December 12-15 , 2010.

Impacts and Contributions/Outcomes

This project will provide an opportunity to identify specific invertebrates and vertebrates that feed on weed seeds in North Carolina. It will also allow us to quantify the impact each of these groups has on the weed seed bank in organic cropping systems, in response to different types of field border vegetation.

If weed seed predation can be encouraged through field border management, conservation biological control of weeds may be a viable option for growers. This is especially important for organic growers who need innovative, sustainable weed management strategies as an alternative to tillage.