Exploration of Soil and Weather Factors on Mulberry Root Rot Incidence in the Western Zone of Tamil Nadu, India

Aims: To record the occurrence of mulberry root rot disease, epidemiology, interaction of weather and soil parameters with the soil-borne pathogens in Western zone of Tamil Nadu during 2019-2020.

Study Design: Survey.

Place and Duration of Study: Surveyed in Coimbatore, Tiruppur, Erode, Dharmapuri and Krishnagiri districts of Tamil Nadu. Laboratory experiments were carried out at Department of Sericulture & Department of Plant Pathology, Tamil Nadu Agricultural University (TNAU), Coimbatore between July 2019 and Jan 2021.

Methodology: Per cent disease incidence of root rot was recorded in all surveyed gardens. To analyze the soil and weather parameters, the composite soil samples were subjected to textural analysis and weather data were collected from TNAU Agro Climate Research Centre. To predict soil temperature for all surveyed locations, the model regression equations were derived. The correlation analysis was done between per cent disease incidence, weather and soil parameters.

Results: The highest disease incidence was recorded in Nallampalli block of Dharmapuri district (54 per cent) whereas the lowest in Udumalaipettai block of Tiruppur district (0.06 per cent). The infected mulberry root samples yielded complex of soil-borne pathogens including Macrophomina phaseolina, Lasiodiplodia theobromae, Fusarium sp., and pathogenicity was proved. The results revealed that root rot incidence was recorded in all types of cultivars, significantly in ruling variety V1 irrespective of its age, soil type, spacing, and irrigation method. Soil parameters like texture, temperature and moisture content were found to augment the disease. Per cent disease incidence had significantly positive correlation with the weather factors like air and soil temperature whereas negative correlation with relative humidity and rainfall.

Conclusion: Synergism of abiotic stress factors hinders the mulberry plant health and increases its susceptibility to the soil-borne pathogens.