55 Journal of Biological Control, 30(1): 55-59, 2016 Research Article C. F. GLEENA MARY * and SALLY K. MATHEW Department of Plant Pathology, College of Horticulture, Kerala Agricultural University, Vellanikkara, Thrissur - 680656, Kerala, India. * Corresponding author E-mail: gleenashaj@gmail.com Efficacy of lignophenolic composts for the management of bacterial wilt of tomato (Article chronicle: Received: 14-11-2015; Revised: 14-02-2016 ; Accepted: 06-03-2016) ABSTRACT: Bacterial wilt is one of the most dreaded diseases in tomato growing areas all over the world. Though chemical control measures and resistance breeding offers certain degree of protection against wilt pathogen, both have their own limitations such as high cost, environmental impact, non target effect and development of resistance. Hence, biologically safe methods such as use of composts as soil amendments for wilt management was investigated in the present study which revealed the possibility of the use of ligno-phenolic composts in disease management. Among the five composts tested, application of ayurvedic compost at 45 days after planting was found to be the most effective with lowest wilt incidence of 6.94 per cent against 36.10 per cent in control, with 80.77 per cent disease reduction. At 60 DAP, same trend was noticed with minimum disease incidence in ayurvedic compost (13.88 %) which was on par with full basal application of leaf litter compost (15.27 %), and coir pith compost (16.66 %) with 86.79 to 60.02 per cent reduction of wilt incidence. In case of yield, among the different composts, split and basal application of ayurvedic compost recorded highest yield of 8.9 kg/6.48 m 2 . KEY WORDS: Ayurvedic compost, bacterial wilt, coir pith compost, leaf litter compost, tomato INTRODUCTION The bacterial wilt disease incited by Ralstonia solan- acearum (Smith) Yabuuchi et al., 1995 is one of the most ubiquitous and damaging bacterial disease in tropical and subtropical countries (Kelman, 1953; Hayward, 1991). It is widespread throughout India and a yield loss upto 100 per cent was reported (Sadhankumar, 1995). The versatility and soil borne nature of the pathogen makes the chemical dis- ease control difficult and costly. Location specific biocon- trol measures for disease control are probably the cheapest strategies available and the most satisfactory from an eco- logical point of view. Kerala being the land of coconut and ayurveda, gen- erates sizeable amount of agrowastes as by products from coir and ayurvedic medicine manufacturing units. Moreo- ver, the plantations of cashew and teak also add to the agrowastes with less degradability. These agrowastes rich in cellulose, lignin, phenols /tannins are normally resistant to biodegradation and takes longer period for degradation. Even though these chemicals lower the degradability of agrowastes, they are found to be inhibitory to several patho- genic microorganisms. Hence in this study we explored the disease management potential of the composts from ligno- phenolic agrowastes against bacterial wilt of tomato. MATERIALS AND METHODS Preparation of ligno-phenolic composts Microbial degraders with the ability to degrade cel- lulose, lignin and tannin/phenols were isolated on their respective selective media. Cellulose degraders were iso- lated on Dubo’s medium for cellulose degraders (Deokar and Sawant, 2004), lignin degraders on lignin sulphonate medium (Thimmaiah, 1989) and tannin degraders on tannic acid medium (Thormaan et al., 2002). The most efficient degraders were selected based on in vitro studies on media as well on their host substrates. They were further evaluated in vivo on host as well as other lignin-tannin rich substrates and a microbial consortium was developed with 10 most efficient, mutually compatible degraders. This consortium was evaluated for its efficacy in reducing the composting period of lignin–tannin/phenol rich substrates viz. ayurve- dic waste, coir pith, leaf litters of cashew, teak and mango and also on the mixture of all these substrates in a field level aerobic composting experiment. These composted agrowastes were evaluated for their potential for the man- agement of bacterial wilt in this study. Field evaluation of ligno-phenolic composts A field experiment was conducted in the research plot to study the efficacy of ligno-phenolic composts in the