Organic Farmer Adoption of a Sudangrass Cover Crop for Suppressing Canada Thistle

Canada thistle (Cirsium arvense (L.) Scop.) is an increasingly difficult weed to control low herbicide and organic farming systems. Canada thistle can spread from wind-blown seed, on equipment, or from contaminated crop seed, hay, or amendments. Once established, Canada thistle can become perennial in as little as five weeks and patches may persist and spread for decades.  Tillage can spread thistle root pieces and most cover crops are not present during seed production and greatest movement of carbohydrate reserves into the roots. Abram Bicksler, in previous research found that sudangrass was effective in suppressing Canada thistle through the following growing season. The objective of our research and outreach project was to foster the adoption of sudangrass summer covers and improve knowledge and management of Canada thistle.  The project was widely advertised throughout the Midwest through press releases, promotion, farmer meetings, web postings, and articles. Forty – one farmers participated during the three years of our project. The on-farm research found that multiple early tillages were critical to suppress Canada thistle and cut root systems into small pieces whose carbohydrate reserves could be depleted. They also found that seeding sudangrass before mid-June and managing the crop residue was important for success of the system. The on-farm project ended in 2010, but farmers are still using and evaluating the system.