Combined application of botanical formulations and biocontrol agents for the management of Fusarium oxysporum f. sp. cubense (Foc) causing Fusarium wilt in banana R. Akila ⇑ , L. Rajendran, S. Harish, K. Saveetha, T. Raguchander, R. Samiyappan Department of Plant Pathology, Centre for Plant Protection Studies, Tamil Nadu Agricultural University, Lawley Road, Coimbatore 641 003, TamilNadu, India article info Article history: Received 10 August 2009 Accepted 22 February 2011 Available online 6 March 2011 Keywords: Fusarium wilt Fusarium oxysporum f. sp. cubense Datura metel Peroxidase Polyphenol oxidase Pseudomonas fluorescens 1 Bacillus subtilis abstract Plant products along with biocontrol agents were tested against Fusarium wilt of banana caused by Fusarium oxysporum f. sp. cubense (Foc). Of the 22 plant species tested, the leaf extract of Datura metel (10%) showed complete inhibition of the mycelial growth of Foc. Two botanical fungicides, Wanis 20 EC and Damet 50 EC along with selected PGPR strains with known biocontrol activity, Pseudomonas flu- orescens 1, Pf1 and Bacillus subtilis, TRC 54 were tested individually and in combination for the manage- ment of Fusarium wilt under greenhouse and field conditions. Combined application of botanical formulation and biocontrol agents (Wanis 20 EC + Pf1 + TRC 54) reduced the wilt incidence significantly under greenhouse (64%) and field conditions (75%). Reduction in disease incidence was positively corre- lated with the induction of defense-related enzymes peroxidase (PO) and polyphenol oxidase (PPO). Three antifungal compounds (two glycosides and one ester) in D. metel were separated and identified using TLC, RP-HPLC (Reverse Phase-High Pressure Liquid Chromatography) and mass spectrometry. In this study it is clear that combined application of botanical formulations and biocontrol agents can be very effective in the management of Fusarium wilt of banana. Ó 2011 Elsevier Inc. All rights reserved. 1. Introduction Banana (Musa sp.) is one of the oldest fruits known to mankind. It is considered as the fourth most widely consumed food crop in the world after rice, wheat and corn based on gross value (http:// www.suite101.com). India ranks first in terms of production accounting for 26 million MT (http://faostat.fao.org). Among the various constraints affecting banana cultivation, Fusarium wilt caused by Fusarium oxysporum f. sp. cubense (E.F. Smith) Snyder and Hansen (Foc) is considered one of the most important threats in Asia, Africa, Australia and tropical America (Hwang and Ko, 2004). In Tamil Nadu, India, the disease was highly destructive on the apple flavor cv. Rasthali (Lakshmanan et al., 1987). At pres- ent the disease is widespread in almost all the banana growing re- gions of India and varieties like Rasthali (AAB) and Virupakshi (AAB) are highly susceptible to this disease and threatened with extinction (Thangavelu et al., 2001). Fusarium wilt is a classic vas- cular wilt disease in which the fungus occludes the xylem vessels causing water blockage. It survives in soil for long periods and thus susceptible genotypes cannot be grown in an infested field for up to 30 years (Ploetz, 2000). The symptoms become evident after 5–6 months of planting and are expressed both externally and internally. The disease causes yellowing of leaf margin of oldest leaves, hanging of leaves around pseudostem, splitting of pseudo- stem and yield losses in the later stages. Plants affected by wilt generally produce unmarketable bunches and the disease ulti- mately destroys the entire plant. Various control measures have been practised to manage this disease, including destruction of diseased plants, sanitary mea- sures, use of disease-free tissue culture planting material, use of tolerant variety and other integrated management methods. Chemicals are also widely utilized for the management of this dis- ease. However, indiscriminate use of chemicals is known to cause health hazards to human beings besides warranting repeated application. As an alternative approach, biocontrol agents are being used for the management of various diseases (Kavino et al., 2008; Harish et al., 2009a). Botanicals with antifungal compounds have been identified and these can be exploited for the management of diseases (Kagale et al., 2004). Botanicals have low mammalian toxicity, target specificity, biodegradability and contain many ac- tive ingredients in low concentrations, thus possess biocidal activ- ity against several insect pests and pathogens (Harish et al., 2008; Kalaycioglu et al., 1997). Kagale and coworkers (2004) documented that the methanolic extract of Datura metel exhibited 85% reduc- tion of mycelial growth of Rhizoctonia solani. In addition, aqueous leaf extract of D. metel was known for its antifungal activity against late leaf spot and rust pathogens, Phaeoisariopsis personata and 1049-9644/$ - see front matter Ó 2011 Elsevier Inc. All rights reserved. doi:10.1016/j.biocontrol.2011.02.010 ⇑ Corresponding author. E-mail address: akilpatho@gmail.com (R. Akila). Biological Control 57 (2011) 175–183 Contents lists available at ScienceDirect Biological Control journal homepage: www.elsevier.com/locate/ybcon