Biocontrol of Potato Common Scab Cultivated on Different Soil Mulch

Potato common scab causes significant economic losses worldwide, and current control methods remain ineffective. However, biological control methods have been effective in controlling phytopathogens in several other crops. Trichoderma spp. and Bacillus subtilis are the most studied microorganisms in agriculture for controlling plant diseases. However, interactions between these biological control agents and the organic matter present at the cultivation site have not been extensively studied. Therefore, the objective of this study was to evaluate the action of biological agents in controlling potato common scab using different soil mulch compositions. Two field experiments were performed simultaneously: one tested T. longibrachiatum (TL) and T. asperellum (TA) treatments in the control of potato scab, and the other tested two types of soil mulch (vetch and palisade grass) and four microorganism treatments (TL, TA, B. subtilis + Enterococcus faecium + Lactobacillus plantarum (BSEFLP), and B. subtilis + B. licheniformis + T. longibrachiatum (BSBLTL)). In the first experiment, TL and TA decreased the disease severity from 80% in the control to 34%, and 56% in the control to 5%, respectively, based on yield losses caused by the potato scab. In the second experiment, TA and BSEFLP reduced the disease severity to 61% and 62%, respectively, compared with that in the control (98%), and losses caused by the common scab to 38% and 40%, respectively, when combined with vetch mulch (control: 98%), demonstrating that microbial response can be influenced by the cover crop. Therefore, this work provides evidence that biological control of potato common scab is a viable alternative for disease control.