Innundative biocontrol of water hyacinth (Eichhornia crassipes (Mart.) Solms. Laubach) using zonate leaf spot (Acremonium zonatum Sawada gams) fungal agent

Abstract

Innundative approach of biocontrol involves culturing spore inoculum for use as a concentrated formulation able to withstand storage, handling and application in weed control the same way as a chemical herbicide. A trial was set up in Maseno University glass house to test the effect of concentrating and formulating A. zonatum spores in vegetable oil, mineral oil, pure commercial grade glycerol and tween 80 for use in water hyacinth biocontrol. A. zonatum was isolated from infected plants collected from Winam gulf (Lake Victoria) Kenya, cultured on PDA under aseptic conditions. The isolate was later multiplied on several PDA plates and spores harvested when mature, concentrated and formulated in 4 different oil emulsions. Fresh healthy water hyacinth plants were then collected from Winam gulf, injured and inoculated in a glass house in RCBD design, replicated 3 times. The results show that concentrating and formulating A. zonatum in vegetable oil and mineral oil may enhance its efficacy as a mycoherbicide, evidenced by the extensive leaf infection, though new leaves continued to form. A. zonatum concentrated and formulated can be used in the control of water hyacinth in the Winam gulf and L. Victoria in general. Suitability of an integrated approach with other insects should be investigated.