Use of a summer cover crop as a partial carbon source for anaerobic soil disinfestation in coastal California
A series of anaerobic soil disinfestation (ASD) experiments were conducted using a summer cover crop as a partial carbon source in coastal California with the goal of reducing ASD's external input. A randomized complete block-designed field trial with six cover-crop plots (open-pollinated broccoli, mustard, FL104 rye, Italian rye, Sudan grass, triticale) plus no cover-crop plots (weeds only) and rice bran 20 t ha‑1 plots was conducted to control Fusarium oxysporum f. sp. fragariae (F.o.f) in Watsonville, CA. Cover crops were grown from May to July 2017. The highest biomass was obtained for triticale, FL104 rye, and mustard (6-7 dry biomass t ha‑1), while the remaining did not produce sufficient biomass due to the moderate air temperature (average 14°C) typical in the area. Cover crops were mowed and incorporated with rice bran added at a rate to provide a total of 20 t ha‑1. A flat ASD treatment with clear totally impermeable film (TIF) was conducted from July to August 2017. Strong anaerobic conditions developed during ASD treatment in all plots, and soil temperature under the clear TIF at 20 cm depth averaged 31°C despite average air temperatures as low as 15°C. Findings indicated that this approach significantly reduced F.o.f. inoculum density regardless of the cover-crop type when the summer ASD treatment period was extended for 5 weeks or longer. A pot trial using the same experimental design yielded effective suppression of Verticillium dahliae in naturally infested soil with a 3-week autumn ASD treatment at lower soil temperature conditions. Together, the present study demonstrated that summer cover crops can be an effective partial ASD carbon source for the control of F.o.f. and V. dahliae.
Muramoto, J., Shennan, C., Mazzola, M., Wood, T., Miethke, E., Resultay, E., Zavatta, M. and Koike, S.T. (2020). Use of a summer cover crop as a partial carbon source for anaerobic soil disinfestation in coastal California. Acta Hortic. 1270, 37-44
strawberry, alternative to fumigants, Fusarium oxysporum f. sp. fragariae, Verticillium dahliae, cover crop