Natural Vegetation and its Influence on Weed Populations in Neighboring Fields

Natural Vegetation and its Influence on Weed Populations in Neighboring Fields

Summary

Natural vegetation on farms such as field margins, fallow fields, ditch canal banks, and wooded areas provide increased biodiversity, structural diversity, habitat for wildlife and beneficial insects, and can act as protective buffers against agrochemical drift. Nevertheless, farmers frequently view these areas as potential sources of pests such as weeds, insects, and diseases. By determining a relationship between plants in the field margin and weeds in the crop field, the managed/natural ecotone can be manipulated to avoid inefficiencies and errors in management leading to pest problems. Plant composition of natural areas of vegetation and weed populations in neighboring fields were assessed to understand the nature of the distribution of weed species from natural areas across the field border to 50 meters into the crop field and determine an association between the plant populations in the two ecosystems. No association was found between plant communities across this managed/unmanaged ecotone.

Objectives/Performance Targets

1. To examine the relationship between field margins and the abundance and distribution of weedy species in adjacent crop fields

   To determine if crop edges adjacent to unmanaged field margins experience higher weed species diversity and density than crop edges bordering managed areas

   To understand the distribution of weedy species in the field with respect to distance from the field edge

   To assess the presence of weedy species in the field margins and boundary areas

   To determine if presence in the field margin or field margin type is associated with the appearance of the weed in the crop field

Accomplishments/Milestones

Plant communities in the field margins and weedy species in crop fields were assessed in May and September 2003. Preliminary results have been determined for all objectives. Field edges adjacent to unmanaged field margins do not experience higher weed species density and, in fact, experience slightly lower species diversity than crop edges bordering managed areas. For total counts, density of weedy species was higher at the field edge than at points closer to the center of the field. Weedy species have been found to contribute only 20-40% of species diversity to unmanaged field margins. Based on analysis of ten dominant weed species, no statistical association has been found between weedy species appearing in the field margin and in the crop field. Results indicate that presence of a particular weed in the field border and border type are not associated with the appearance of the same weed in the crop field.

Impacts and Contributions/Outcomes

Preliminary results were presented at the Center for Environmental Farming Systems Annual Field Day in Goldsboro, NC on September 5, 2003 to visiting extension agents and faculty from North Carolina and other Southeastern states. Results were also presented at the Northeastern Weed Science Society of America Annual Conference on January 6, 2004 in Boston, MA.