While organic production of specialty crops has been highly successful in southern California, it relies heavily on the use of plastic mulch and intensive tillage for weed management. A two-year study conducted from 2022 to 2023 aimed to evaluate the impact of plastic mulch and a cover crop based reduced tillage system using a -roller crimper to terminate cover crops on weed pressure and yield in organic strawberry production. Bare root strawberry crowns of the Albion variety were transplanted into four treatments: 1) Sorghum-sudangrass (S. bicolor x S. sudanense) seeded at 100 kg/ha (Sorghum 1), 2) Sorghum-sudangrass seeded at 200 kg/ha (Sorghum 2), 3) buckwheat seeded at 67 kg/ha, or 4) plastic mulch as standard practice. Cover crops were broadcasted on 1.5 m wide raised beds in May and terminated with a roller crimper in August. Both seeding rates of Sorghum-sudangrass effectively suppressed weed growth before and after termination compared to buckwheat. The significantly lower biomass of buckwheat after termination, relative to the Sorghum-sudangrass treatments, indicates variations in weed suppression efficacy among cover crops. Total differences in soil moisture, calculated based on data collected weekly from after cover crop termination to end of harvest, indicate that all treatments resulted in lower soil moisture levels compared to the plastic control, with the buckwheat treatment showing the most significant decrease. At harvest there were no significant differences between plastic mulch and Sorghum-sudangrass 1 and 2 treatments, indicating comparable yields. Buckwheat resulted in the lowest yield, experiencing a 50% reduction compared to plastic mulch. Based on the findings, plastic mulch and Sorghum-sudangrass planted at different seeding rates can be considered effective alternatives for weed suppression and maintaining yields comparable to conventional plastic mulching. The choice between Sorghum-sudangrass seeding rates may depend on factors such as cost, availability, and specific field conditions. The reduced biomass production of buckwheat compared to Sorghum-sudangrass, coupled with its rapid decomposition rate, resulted in diminished efficacy of buckwheat in weed suppression. Consequently, reduced weed control was observed, leading to significantly lower yields in buckwheat-treated plots compared to Sorghum-sudangrass and control treatments. These findings suggest that buckwheat may not be a viable option for organic strawberry production under comparable conditions, emphasizing the importance of selecting cover crops with longer-lasting weed-suppressive qualities.
