In Vitro Screening for Effective Antagonists of Sclerotium rolfsii Sacc., A Causal Agent of Tomato Stem Rot

Abstract

Ninety-seven soil samples were collected from five locations in Kamphacng Scan; Nakhon Pathom. Each sample consisted of three subsamples including soils around Selerotium infected, and healthy tomato plants as well as selerotia- adhering soil. Fungi (936 isolates) and bacteria (115 isolates) were isolated through the use of serial dilution technique placing soil suspension on the agar surface of Martin’s medium, and Thornton’s medium and KMB, respectively. Attained fungi could be divided in seven groups including, Aspergillus flavus group (80 isolates), Aniger group (129 isolates), Aspergillus group “A” (66 isolates), Aspergillus group “B” (62 isolates), Phycomy-cetous group (30 isolates), Trichoderma-Glioclagium group (147 isolates) and unidentified group (422 isolates). For bacteria, Bacillus spp. (50 isolates) and Pseudomonas spp. (fluorescent group)(65 isolates) were identified. Evaluation of bacteria for the inhibition of mycelia growth of Sclerotium rolfsii revealed that 18 isolates of Bacillus species and one isolate of P.fluorescens produced inhicition (clear) zone (2-5 mm. width). In vitro evaluation for the Sclerotium inhibitive isolates of Trichoderma-Gliocaladium group indicated 123 isolated showing inhibitive reaction.