Expanding classical biological control of weeds with pathogens in India: the way forward.
Invasive alien weeds are a major constraint in agriculture, forestry and the environment in India. Classical biological control (CBC) of these exotic weeds through deliberate introduction of arthropods is almost a century-old practice. History has recently been made with the successful introduction of the first plant pathogen, Puccinia spegazzinii de Toni, against mikania weed (Mikania micrantha H.B.K.) in India. With the mechanism in place for the importation, quarantining and release of pathogens, it is envisaged that more introductions will be made in the future. The agent under immediate consideration is Puccinia abrupta Diet. and Holw. var. partheniicola (Jackson) Parmelee against parthenium weed (Parthenium hysterophorus L.), generally considered as the worst terrestrial social weed in India. Down the line, other terrestrial weeds such as Chromolaena odorata (L.) R. King and H. Robinson and Lantana camara L. and aquatic species like Eichhornia crassipes (Martius) Solms-Laubach could be targeted for pathogens. This article, besides presenting an overview of the research that has gone into selection of candidate fungi for CBC of M. micrantha and P. hysterophorus, also analyses the infrastructure and expertise requirements for further expanding the target list.