2019 ASHS Annual Conference

The sulfur containing compounds can be used as additives to improve the efficiency of steam application in agricultural fields. Our previous studies demonstrated that allyl-isothiocyanate (AITC) and mustard seed meal (MSM) suppressed growth and germination of weeds and plant pathogens. The objective of this study was to investigate the synergistic effect of steam and the sulfur containing compounds against weed seeds and a plant pathogen. This experiment was conducted on June 15 and October 24, 2018. Four weed seeds (knotweed, purslane, pigweed, and nettle) and a strawberry pathogen (Verticillium dahliae) were enclosed in nylon bags and introduced in microplots at 100 mm depth and 0.3, 0.5, and 0.7 m distant from the center. Dominus (99.8% AITC) was applied at the center of microplots (18.7 mL m^-2), and MSM was applied at (333 g m^-2). Steam was applied at a pressure of 5 bar for 60 min in the center of microplots. The maximum soil temperatures at 0.3, 0.5, and 0.7 m from the center of steam treatment were 99.6, 99.7, and 99.5°C and time of above 65^oC was 191.5, 136.5, and 115.5 minutes, respectively, while the maximum soil temperatures were 20.3^oC at 0.7 m and 30.8^oC at 0.3 m in non-steamed microplots. The steam treatments such as steam only, steam + MSM, steam + Dominus, and steam + Dominus
+ MSM showed a significant decrease in the weed seed viability and germination of V. dahliae in all distances compared to control, but MSM only and Dominus only treatments didn’t. The steam + Dominus treatment, especially, reduced the viability of pigweed and nettle seed at 0.7 m distance compared to steam only and Dominus only treatments. The results suggest that Dominus can complement the effect of steam application for soil disinfestation.