Weed and pathogen control with steam in California strawberry production

Here we report on results of weed and pathogen control with steam over a period of four seasons (2011/12 to 2014/15). Furthermore we discuss effects of steam on plant performance, fruit yields and soil microbial community. Steam was applied by a proto-type tractor towed steam machine equipped with a Clayton steam generator. We discuss the efficacy of steam compared to fumigants and non-chemical soil disinfestation methods in California. Steam controls weeds, soil borne pests, while strawberry yields in steam treated soil normally are 20% higher, compared to common non-chemical pre-plant soil disinfestation treatments in CA. Our results suggest that the benefits of steam are due to combined effects of extra nutrient release, reduction of pathogen pressure and changes in microbial community structure. We are currently separating those effects in controlled experiments. Furthermore we investigate steam-induced changes in soil microbial community and the utilization of steam in combination with allyl isothiocyanate (AITC) and cover crops as management tool. A commercial broadcast field steam applicator is being developed in cooperation with industry.