Parthenium management by cultural filtrates of phytopathogenic fungi.

In the present study, herbicidal activity of culture filtrates of nine phytopathogenic fungi, namely, Alternaria alternata (Fr.) Keissl., Drechslera australiensis (Bugnicourt) Subramanian & Jain, Drechslera hawaiiensis (Curtis and Cooke) Shoemaker, Drechslera biseptata (Saccardo & Roumeguere) Richardson & Fraser., Drechslera rostrata (Drechsler) Ricardson & Fraser, Fusarium oxysporum (Massey) Synd. & Hans., Fusarium solani (Martius) Saccardo., Monilia stophila (Montagne) and Cladosporium sp. (Grey) de Hoff, was evaluated against parthenium weed (Parthenium hysterophorus L.). In laboratory bioassays, the effect of original (100%) as well as lower concentrations (75, 50 and 25%) of these cultural filtrates was studied on germination and early seedling growth of parthenium. Cultural filtrates of different concentrations of A. alternata, Cladosporium sp. and D. rostrata significantly suppressed the germination of parthenium seeds by 70-90, 13-73 and 27-50%, respectively. Cultural filtrates of these fungi also exhibited pronounced adverse effects on the seedling root and shoot growth. Among other fungal species, cultural filtrates of D. australiensis, D. hawaiiensis, F. oxysprium and F. solani significantly reduced the root and shoot length of parthenium seedlings. Foliar spray bioassay was performed using cultural filtrates of three fungal species, namely A. alternata, F. solani and D. rostrata. In this bioassay, three sprays of fungal cultural filtrates, with 4 day intervals each, were carried out on 1 and 2 week-old pot-grown seedlings of parthenium. Cultural filtrates of all the three fungal species markedly suppressed root and shoot growth of parthenium weed.