Estimating Weed Seed Banks for Improved Monitoring and Management of Weeds
Project Leader: D. Brainard, Dept. of Horticulture, Cornell University
Cooperators: R. Bellinder , Dept of Horticulture, Ithaca; et.al.
Abstract: The major objectives of this project were (i) to develop a low-cost method for estimating weed seed banks, and evaluate its potential as a fee-based service for growers, (ii) to assess the effects of winter cover crops on weed seed banks using this method. A simple weed seed bank estimation procedure was established in which soil samples from growers’ fields were mixed with potting soil, spread thinly in flats in a greenhouse and monitored for emerged weed seedlings. To reduce costs, only the top 10-15 summer annual weed species were identified by species, and emergence counts occurred for only 4 weeks. Samples from 21 fields and two replicated long-term field studies were taken and their seed banks estimated. The simple method was compared to a more intensive method previously developed for research purposes. For two sites, weed seed bank estimates were compared to emergence of weeds in the field. In addition, weed seed bank estimates from treatments involving four years of winter cover crops (rye and hairy vetch) were compared to bare-soil treatments. The simple seed bank assessment was estimated to cost approximately $10 per sample. Seed bank estimates using this method correlated reasonably well with field emergence, and provided similar information to more intensive methods of estimating weed seed banks. Contrary to expectations, treatments with a history of winter cover crops had equal or higher estimated weed seed banks than those without winter cover crops. Ongoing research will assess the effects of fall versus spring sampling, and evaluate the potential value of these seed bank estimates for guiding crop-rotation and weed management decisions on farms.