EFFICACY OF SELECTED FUNGICIDES ON THE LINEAR COLONY GROWTH OF THE HELMINTHOSPORIUM ORYZAE CAUSED BY BROWN SPOT DISEASE OF RICE

Abstract

Brown spot of rice caused by Helminthosporium oryzae, attacks the plant at any growth stage and it
appears on the foliage as scattered brown spot that coalesces and result in withering and yellowing of the leaves.
This fungal disease lowers the seed germination, causing rotting of seeds and roots that ultimately reduce yield by
16% to 43%. The method followed was based on survey and sampling of diseased seed samples from Larkana.
Isolation and purification of fungi from these samples were conducted and performed pathogenicity test of the most
predominant isolated fungus (H. Oryzae). So, this study was aimed to evaluate different fungicides. In vitro study of
four fungicides efficacy revealed that Mencozeb and Thiomal completely inhibited growth of the test fungus. H.
oryzae failed to grow at 150 and 200 ppm, (00. mm) as compared to control (36.62 mm) respectively. Whereas,
Bavistin was moderately effective (10.50 mm) and Melody duo was less effective (12.87 mm) as compared to
control (36.62 mm). So, one can conclude that Mencozeb and Thiomal was the most effective fungicides. These
studies could be helpful for researchers and farming community in future for better management of this disease.