Use of Waste Vegetable Biomasses Treated by Steam Explosion for the Horticultural Crop Protection

The purpose of this study was to assess the suppressive effect of Waste Vegetable Biomasses (WVBs) treated by the Steam Explosion technique in a continuous plant, against soil-borne plant pathogens. In order to assess their disease suppression, five WVBs (Miscanthus biomass, durum wheat straw, rice straw, corn stalk and wood shaving) and commercial compost were tested in vivo at three different doses (10, 20 and 30% of potting mix) on seven horticultural pathosystems plant/fungus: tomato/Phytophthora nicotianae, cucumber/Pythium ultimum, lettuce/Fusarium oxysporum f. sp. lactucae, melon/Fusarium oxysporum f. sp. melonis, bean/Rhizoctonia solani, eggplant/Verticillium dahlie and fennel/Sclerotinia sclerotiorum. The results showed that the corn stalk was more efficient respect to Miscanthus, compost, wheat straw, rice straw and wood shaving in all the pathosystems and at all the doses tested. The corn stalk suppression ranged from 97% in eggplant/V. dahliae to 35% in lettuce/F. oxysporum f. sp. lactucae, and it was significantly higher with respect to the other substrates. In general, the wheat straw, rice straw and wood shaving were statistically found less efficient as suppressive substrate with respect to corn stalk, Miscanthus and compost at the 30% dose in four pathosystems. In particular, the wood shaving suppressiveness ranged from 48% in eggplant/V. dahliae to 12% in lettuce/F. oxysporum f. sp. lactucae. The different suppressiveness observed could be attributed to different concentration of the microbial inhibitory substances (furfurals, organic acids and lignosulfonates) produced during the processing of fresh biomass.