5.2.80
MANAGEMENT OF SEEDLING ROOT ROT OF DALBERGIA SISSOO CAUSED BY FUSARIUM SOLANI

JC KAUSHIK

Dept. Agroforestry, Haryana Agricultural University, Hisar 125004, India

Background and objectives
Root rot caused by Fusarium solani f.sp. dalbergiae is a serious disease of Dalbergia sissoo in almost all the forest nurseries located in different parts of Haryana state, India. It causes 60-80% losses particularly in heavy and wet soils [1]. At present no effective control measures for the disease are available. Biological as well as chemical control methods were investigated.

Results and conclusion
Seven systemic and non-svstemic fungicides were used in five concentrations (50, 100, 200, 400, 500 ppm) against mycelial growth of F.solani (poisoned food techniques). Out of these Bavistin, Captan, Topsin-M, Thiram and Dithane M-45 were found promising under in vitro conditions. These fungicides were further tested under field conditions through seed and soil treatment. Pooled results for 3 years revealed that Bavistin was found to be most effective fungicides controlling more than 75% disease. In general, seed treatment method was better than soil drenching. Three biocontrol agents, Trichoderma harzianum, T.viride and Bacillus subtilis were tested in in vitro and in vivo against F. solani. ln vitro T.harzianum and B. subtilis reduced the radial growth of the pathogen to 70 and 64%, respectively. ln vivo T.harzianum gave 65 and 60% pre- and post-emergence disease control, respectively. Soil solarization through mulching was done for 15, 30, 45 and 60 days during the hot summer months (April-June) when the atmospheric temperature ranged between 40 and 47C using transparent polythene sheet (150 gauge). It increased the soil temperature from 4 to 5C up to a depth of 5 cm. Fusarium solani could not be recovered after mulching for 60 days. The disease incidence in 60 days mulched soil was reduced from 80% in control treatment to 10%.

References
1. Kaushik JC, Singh, Ajit 1996. Proc. IUFRO Symp. on impact of Diseases and Insect Pests in Tropical Forests. pp. 209-216.