Evaluating Cover Crops for Weed Suppression In Organic Hopyards.

Tillage is the traditional method of weed control in hopyards in Washington State.  Organic hop growers often use cover crops to provide organic matter and improve soil quality, but weed control remains a problem.  This experiment is being conducted on a certified organic hopyard near Toppenish Washington.  In this study, six different cover crop treatments and two control treatments are being assesed for their ability to suppress weeds in the drive rows of the hopyard.  Treatments consist of several grasses and leguminous combinations that were chosen for their ability to produce high biomass, survive compaction, and grow vigorously.  Plants were established in the summer of 2010, using a randomized split plot design consisting of eight main plots (cover crop treatments) and four sub-plots (hop varieties) with three replicates per treatment.  Testing was conducted throughout the spring and summer of 2011 and preliminary weed suppression data from the first year of a two year study will be presented.