Prospects of using Fungal Metabolites for the Management of Rumex dentatus, a Problematic Weed of Wheat.

Rumex dentatus L. is a very common weed of wheat (Triticum aestivum L.) in Pakistan. Present laboratory and pot trials were carried out to evaluate metabolites of Drechslera holmii, Drechslera biseptata and Drechslera australiensis as natural herbicides against R. dentatus. Fungal metabolites were prepared in M1D medium. In laboratory bioassays, original and 50% diluted metabolites of different Drechslera spp. significantly reduced seed germination, shoot biomass and root biomass of R. dentatus seedlings by 5-56%, 15-83% and 68-88%, and that of wheat seedlings by 8-20%, 16-38% and 28-38%, respectively. Metabolites of D. biseptata and D. australiensis exhibited greater herbicidal activity than metabolites of D. holmii. In foliar spray repeated pot trials, original metabolites of the three Drechslera spp. significantly reduced shoot biomass of one- and two-week old plants of R. dentatus by 54-60% and 27-46%, respectively. By contrast, the effect of metabolites of all the three Drechslera spp. was non-significant on growth of wheat plants. Metabolites of D. australiensis showed the highest herbicidal activity in pot trials. It is concluded that metabolites of Pakistani Drechslera spp. possess herbicidal potential. [ABSTRACT FROM AUTHOR]