Efficiency of Crude Extracts from Streptomyces spp. for Colletotrichum Leaf Spot Disease (Collectotrichum glocosporioides Penz. Sace.) Control in Poly Bag Para Rubber

Abstract

Colletotrichum leaf spot disease from Colletotrichum gloeosporioides is the major diseases in para rubbers, important economic plants in Thailand. In the present study, C. gloeosporioides were collected in soil from Ratchaburi, Surat Thani and Nakhon Pathom provinces and 25 isolates of Streptomyces spp. were investigated to determine the inhibitory effect on the growth of C. gloeosporioides using dual culture tests. The result showed that Streptomyces sp. SC-1 had an ability to inhibit the growth of C. gloeosporioides then, 5 concentrations of the crude extract from Streptomyces sp. SC-1 which are 346.15 (100%), 259.61 (75%), 173.08 (50%), 86.54 (25%) and 43.27 (12.5%) mg/ml were tested using the paper-disc agar-plate method. 86.54 mg/ml crude extract was the lowest concentration that had no significant difference from of 7.5 mg/ml  benomyl. Therefore, 86.54 mg/ml of crude extract from Streptomyces sp. SC-1 was applied to the leaf of poly bag para rubber. The result was found that the percentage of inhibition was 65.28, 76.85 and 88.43 for 200, 400 and 600 µl of the curde extract, respectively. The percentage of inhibition of 200 µl had no significant difference from that of 7.5 mg/ml benomyl.