3.7.80
MANAGEMENT OF NURSERY DISEASES OF MULBERRY THROUGH INTEGRATED APPROACH

VP GUPTA, RK MISHRA and A SARKAR

Central Sericultural Research and Training Institute, Srirampura, Mysore 570 008, India

Background and objectives
Mulberry (Morus alba), the sole food plant of silkworm (Bombyx mori), is propagated commercially through the plantation of stem-cuttings, either directly to the fields or in nurseries to raise saplings for transplantation. Although suitable planting methods have been suggested for mulberry propagation, its initial establishment is greatly afflicted by the attack of many soilborne pathogens. As a result, the final survivability and growth of plants are adversely affected. A survey conducted in mulberry growing areas of India reveals the incidence of diseases viz., stem-canker and die-back (Botryodiplodia theobromae), cutting rot (Fusarium solani) and collar rot (Phoma sorghina and P. mororum) which affect almost all the popular mulberry varieties cultivated in the country. These diseases cause mortality of cuttings and saplings to an extent of more than 50% [1]. A biofungicide, NURSERY-GUARD using Trichoderma pseudokoningii, has been developed with the aim of biological control of nursery diseases of mulberry [2]. The present study aimed to evaluate the compatibility, and possible additive effects of NURSERY-GUARD with other effective chemical and non-chemical controls.

Materials and methods
The developed biofungicide, NURSERY-GUARD (NG) was evaluated in integration with a chemical fungicide, Mancozeb 75WP (manganese ethylene bisdithiocarbamate plus zinc 75% WP) or a biofertilizer (Azotobactor chroococcum). NG was applied in combination with other control agents as coating on cuttings (cutting-dressing) and/or incorporation in the infested soil (soil disinfection) before plantation. Untreated control was considered as check. Experiment was conducted under field conditions with a susceptible mulberry var. K2. Sapling mortality, survivability and growth, and percentage disease control were recorded 90 days after plantation.

Results and conclusions
Integration of NG with other effective agents enhanced the disease control efficiency ranging from 55.4 to 69.8%, against 43.8 to 54.7% in NG or any other agent alone. Among the various combinations, integration of NG as soil disinfection and Mancozeb 75WP as cutting-dressing was found to be the most effective where disease control was achieved up to 69.8%. It resulted in an increase of 45.9% in sapling production, besides enhancing their growth by 59.5% over untreated check. Integration of cutting-dressing with NG + soil disinfection with biofertilizer, and soil disinfection with NG + cutting -dressing with biofertilizer were also effective which provided 61.5-63.0% disease control, resulting in 40.5-41.5% increase in sapling production and significant increase in growth over check. However, integration of NG + biofertilizer or Mancozeb 75WP both as cutting-dressing did not give encouraging results, compared to the combination of soil disinfection and cutting-dressing. Thus, the results clearly indicated the prospects of using NURSERY-GUARD in integration with other effective chemical and biological agents for the better management of nursery diseases of mulberry.

References
1. Gupta VP, Govindaiah, Raju HV, 1997. Indian Phytopathology 50 (3) [in press].
2. Gupta VP, Sarkar A, 1997. Proceedings International Conference on Integrated Plant Disease Management for Sustainable Agriculture, P5A-032, p. 207.