COMPOST APPLICATION FOR SUPPRESSION OF MACROPHOMINA PHASEOLINA CAUSING CHARCOAL ROT IN ARID CROPS

Abstract

Under warm and dry growing conditions of the Indian arid region, Macrophomina phaseolina (Tassi) Goid., a soil borne plant pathogen, causes charcoal rot in legumes and oil seeds limiting profitable production. Due to lack of resistant cultivars, cultural and biological methods of management are the only option left with the growers of the region. Amending soil with certain weed residues or compost prepared from residues of mesquite (Prosopis juliflora (Swartz) DC) has been advocated for managing Macrophomina in arid regions. In sequel, an effort was made in the present study to integrate native bio-agents in compost in order to improve pathogen control and to induce soil suppressiveness. Four composts were prepared from residues of P. juliflora, neem, Indian mustard and weeds (Euphorbia hirta, Aerva persicae and Celosia argentia). Population of antagonistic actinomycetes to M. phaseolina was maximum (37% increase) in mustard + weed residue compost. In other composts also, there was enhancement in the population of antagonistic actinomycetes compared to non-amended control. Maximum reduction (86.3%) in population of M. phaseolina was estimated in mustard + weed compost amended soil followed by mustard compost (78.4%). Combining weed compost with any compost has improved reduction in M. phaseolina population compared to compost alone. In a two-year field study on cluster bean, incorporation of composts alone or in combination with weed compost were found significantly effective in reducing charcoal rot incidence compared to control. On the basis of two years pooled average, least disease incidence (4.9%) was recorded in P. juliflora + weed compost (3.5+0.5 t ha-1) followed by mustard + weed compost (5.2%) compared to control (10.1%). Significant reduction was estimated in soil amended with mustard + weed compost (70 cfu g-1 soil) followed by P. juliflora and P. juliflora + weed compost at 0-15 cm soil depth after two years of continuous compost incorporation. This study demonstrates that bio-control agent enriched composts improve pathogen and disease control. This can be considered as a low input soil disinfestation alternative for rain fed agriculture.