Evaluation of Biocontrol Agents Against Bacterial Wilt in Tomato Using Seedling Screening

Abstract

Tomato is among the most cultivated vegetable crops worldwide, and bacterial wilt (BW) caused by the Ralstonia solanacearum species complex (RSSC) is the most devastating disease affecting tomato, impacting food and nutrition security in many areas. Pesticides used for controlling plant diseases are hazardous to producers, consumers, and the environment, whereas biological control is potentially a sustainable and environmentally safe alternative for disease management. To identify efficient biocontrol agents (BCAs), twenty-five potential BCA isolates were screened for control efficacy to BW on ten-day-old tomato seedlings of highly susceptible (L390) and moderately resistant (L180) cultivars previously inoculated with R. solanacearum strain PSS4 (=Asian origin, Race 1, Phylotype I; Biovar 3). After ten days incubation at 28 °C in the growth chamber, wilting (W%) and biocontrol efficacy (BE%) percent were evaluated. Of the 25 BCAs tested, four significantly reduced W%, with BE% ranging from 50% to 80% for both varieties. The four BCA isolates were identified as Talaromyces sp., Trichoderma sp., Bacillus sp., and Variovorax sp. The seedling method allows the rapid and cost-effective in vivo screening of many potential BCAs to reliably identify those with higher bacterial wilt control efficacy for further testing.