EFFECT OF SOME CHEMICALS ON THE DEVELOPMENT OF RED ROT, WILT AND SMUT DISEASES OF SUGARCANE R. DWIVEDI Division of plant pathology, Indian Institute of Sugarcane Research, Lucknow-226 002, India. Background and objectives Red rot (Colletotrichum falcatum), wilt (Fusarium moniliforme) and smut (Ustilago scitaminea) are the three major sett transmissible fungal diseases of sugarcane in India. Red rot is most destructive followed by wilt and smut. Although these diseases are known over a century, no definite and effective chemical method is available to contain these diseases under field condition. Most of the fungicides are quite effective in vitro but they become ineffective to check the disease in vivo. The objective of this study was to find out the efficacy of zinc sulphate, boric acid and acetic acid on the above three disease causing pathogens both in vitro and in vivo. Materials and methods The test pathogens used in laboratory studies were isolated from diseased susceptible sugarcane cultivars CO 1148 (C. falcatum) and CO 1336 (F. moniliforme) and cultures thereof were maintained on oat meal agar slants. In all the experiments 0.50-. concentration of zinc sulphate, boric acid and acetic acid was used. For in vitro testing of the chemicals "poisoned food techniquell[1] was adopted. Field experiments were laid out in randomised block design. Diseased three bud setts of CO 1148, CO 1336 and COLK 7901 cultivars were dipped in solutions of individual chemical for 24h and planted in field. Observations on germination and disease development in standing crop were recorded periodically. Results and conclusions There was complete inhibition of mycelial growth and sporulation of pathogens (C. falcatum and F. moniliforme() in vitro. No adverse effect of chemicals on germination of sugarcane cultivars was observed. In control, development of red rot, wilt and smut was 18.6, 50.0 and 22.3 - 06 respectively. In zinc sulphate development of red rot was 1.5%, wilt 0. 0% and smut 3.1%. In boric acid and acetic acid red rot, wilt and smut development was 0.3, 9.5, 2.2% and 2.4, 15.9, 2.2% respectively. These results indicate that the chemicals were found very effective in checking the development of three diseases in vivo [2]. References 1. Carpenter JB,1942.Phytopathology 32,845-56. 2. Ann.Reports, 1994-95 & 1995-96. IISR,Lucknow.