CONTROL OF XANTHOMONAS CAMPESTRIS pv. VESICATORIA USING AGROINDUSTRIAL WASTE-BASED COMPOST

Abstract

Here we review the suppressive capacity of 14 agroindustrial subproduct-based compost against the disease caused by Xanthomonas campestris pv. vesicatoria (Xcv) in tomato crops. The obtained results have shown that the in vitro compost’s suppressive effect on Xcv growth was mainly due to biotic factors, since sterilised compost samples were not effective. The most effective composts were 44TRI, 50, 51, 52 and 55, while the rest of them apparently did not affect the in vitro growth of the bacterium. When the same composts were applied in a tomato seedbed, the sample named 51 showed the most suppressive effect against the symptoms caused by the pathogen. Disease incidence reduction after this treatment reached 80%. In this case, a clear indirect relationship was detected between disease incidence and fresh weight losses of treated plants. Finally, the suppressive characteristics of an agroindustrial-based compost were improved after the inoculation with a biological control agent, a strain of Bacillus pumilus MSW231 known to be effective against Xcv. In this case, the isolation of the pathogen from infected plants was reduced up to 95% as compared to plants treated with another non-suppressive substrate. The present results indicate that the agroindustrial subproducts-based compost posseses an important suppressive effect towards the disease caused by Xcv, mainly due to biotic factors, and therefore it can be improved by the inoculation with biological control agents, worsened by sterilization and even modified by the inoculation with other biological control agents, so as to obtain an effective compost a la carte.