Herbicidal activity of culture filtrates of four
Drechslera spp., namely
D. australiensis
(Bugnic.) Subram. & B.L. Jain,
D.
biseptata
(Sacc. & Roum.) M.J. Richardson & E.M. Fraser,
D. hawaiiensis
Bugnic. ex M.B. Ellis, and
D. holmii
(Luttr.)
Subram. & P.C. Jain, prepared in malt extract broth was investigated against parthenium weed (
Parthenium hysterophorus
L.) in both laboratory bioassays and pots. In laboratory bioassays, the effect of original (100%) and diluted (50%) culture
filtrates of the four
Drechslera spp. was studied on parthenium germination and seedling growth in 90 mm diameter Petri
plates. Original culture filtrate of all the four
Drechslera species significantly reduced germination, shoot length, shoot fresh
biomass, root length, and root fresh biomass of parthenium seedlings by 43 to 77%, 77 to 82%, 69 to 82%, 90 to 92%, and
67 to 83%, respectively, as compared to the control. In pot trials, foliar application of original fungal culture filtrates was
carried out on 1-wk and 2-wk old parthenium seedlings. Culture filtrates of all the four
Drechslera spp., except
D. holmii,
markedly reduced parthenium shoot dry weight. Two-week-old plants were more susceptible to foliar spray than the 1-wk
old plants. There was a 13 to 55% and 28 to 65% reduction in shoot dry weight of 1-wk and 2-wk old parthenium plants,
respectively, due to culture filtrates of various
Drechslera spp. The present study concludes that
Drechslera spp. culture
filtrates can be used as alternative herbicides for parthenium weed management.
