Author : Kasem Soytong

Summary : A survey of CHAETOMIUM occuring in the Philippines soils and animal dung was undertaken. Fifteen species from 88 isolates were studied and identified. These were Ch. anguipilium Ames., Ch. aurangabadense Tilak and Reddy, Ch. bostrychodes Zopf., Ch. brasiliense Batista and Pontual., Ch. carinthiacum Sorgell, Ch. cochliodes Pall., Ch. cuniculorum Fuckel, Ch. cupreum Ames, Ch. erectum Skolko and Groves, Ch. gracile Udagawa, Ch. globosum Kunze, Ch. longirostre (Farrow) Ames., Ch. lucknowense Rai et Tewari, Ch. mollicellum Ames, and Ch. sulphureum Sorgell ex Seth. Except for Ch. globosum, all were new records in the Philippines. C. cupreum Chivers, Ch. globosum Kunze, and Ch. cochliodes Pall. which were isolated from upland rice field soils, were found to be antagonistic to Pyricularia oryzae Cav., Curvularia lunata (Wakker) Boedjin, Drechslera oryzae (Breda de Han) Subram, Fusarium moniliforme Sheld. when grown on dual agar culture. This was based either on competition growth with or without antibiotic activity toward the pathogen. Greenhouse tests showed that coating rice seeds (IR 442-2-58) with either spore suspensions or culture filtrates of Chaetomium spp. and sowing them in soil amended with P. oryzae controlled early infection of the rice blast pathogen which often resulted in aborted seedlings. This suggests than an antagonistic substance that effectively hampers development of P. oryzae, may be produced by CHAETOMIUM. The antagonist coated-seeds also had enhanced shoot emergence which resulted in taller plants, greater root growth, and greater fresh weight of plants. All these were also observed when the seeds were treated with captan. The preliminary results suggested that when certain strains of CHAETOMIUM are established in the soil, rice seedlings may be protected from early infection by P. oryzae in upland rice fields.