Mycoherbicides are special biotechnology products which contain fungi or fungal metabolites as nonchemical alternatives thereby reducing the input of harmful chemicals to control noxious weeds. The present communication emphasizes on the potential of an indigenous isolate of Alternaria alternata ITCC 4896 as a mycoherbicide for the global weed – Parthenium hysterophorus. Of the various spore concentrations tested by in vitro Detached Leaf Bioassay, 1x10⁶ spores/ml was the most effective inducing 89.2% leaf area damage on the 7th day and was further tested by Whole Plant Bioassay. Both in vitro Detached Leaf Bioassay and Whole Plant Bioassay exhibited a similar trend in disease development showing 50% damage at 96 hours post treatment. However, 100% mortality was observed in the Whole Plant Bioassay on the 7th day. This is the very first report on the bioweedicidal potential of A. alternata ITCC 4896 (LC#508) for use as a mycoherbicide for P. hysterophorus.

Two independent pot experiments were conducted to evaluate the potential of two different application methods for culture filtrates of 10 Trichoderma spp. strains to reduce infection of Phelipanche aegyptiaca in tomatoes. In the first method (foliar spray), seedlings were foliar sprayed three times with culture filtrate of each Trichoderma spp. strains pre- and posttransplanting. In the second method (soil drench), these culture filtrates were incorporated into the top 5 cm of the soil surface during transplantation. Foliar sprays of T33, T60, and T36 significantly reduced the progression of P. aegyptiaca infection throughout the growing period (85 days). The number of P. aegyptiacaʹs aboveground stalks and underground juveniles was also significantly reduced (83 and 66%) in T33-treated plants at the end of the experiment, while the fresh and dry weights of tomato fruits was significantly increased (86% and 90%). In the second approach, T66, T33, T35, T36, and T67 strains caused a significant reduction in the progression of P. aegyptiaca infection on tomatoes during the same period. The fresh and dry weights of stalks and attached juveniles of P. aegyptiaca in T66-treated plants were significantly reduced by 77, 52, 75, and 49%, respectively, compared to the control. The conclusion showed that T. virens T33 culture filtrate as foliar spray through some kind of induced systemic resistance (ISR) and T. brevicompactum T66 culture filtrate as soil drench can be used as natural bioherbicides to control P. aegyptiaca in tomatoes.