Abstract

In the present study, herbicidal activity of metabolites of four fungi namely Drechslera hawaiiensis M.B. Ellis, D. biseptata (Sacc. and Roum.) Richardson and Fraser, D. holmii(Luttr.) Subramanian and Jain, and D. australiensis (Bugnicourt) Subramanian and Jain., was evaluated against Phalaris minor Retz., a problematic monocotyledonous weed of wheat. Fungal metabolites were prepared by incubating the fungal species in M-1-D medium for 28 days at 25 °C. In laboratory bioassays, the effect of original (100%) and diluted (50%) fungal metabolites was studied on germination and seedling growth of the target weed species. All the four fungal metabolites significantly reduced seed germination, and shoot and root growth of seedlings of the test weed species. The highest activity against seed germination was exhibited by metabolites of D. australiensis resulting in up to 94% reduction in the studied parameter. Similarly the best herbicidal activity against shoot growth was due to metabolites of D. hawaiiensis where 65% and 64% reduction in length and dry biomass of shoot was recorded. In foliar spray pot bioassays, fungal metabolites were sprayed on 1-week and 2-week old weed plants four times with 4 days intervals. In general, the effect of the fungal metabolites on various shoot and root growth parameters was insignificant. The present study concludes that metabolites of D. australiensis can be used as potent pre-emergence herbicides for the management of P. minor.

Key words: Alternative herbicides, fungal metabolites, littleseed canarygrass, Phalaris minor, weed of wheat.