Effect of Cercospora piaropi Tharp and Myrothecium roridum Tode Fries Formulated as Corn Oil Emulsion on Water Hyacinth Shoot Growth under Greenhouse Conditions

Abstract

A study was done to find out the comparative effect of Cercospora piaropi Tharp and Myrothecium roridum Tode Fries formulated as corn oil emulsion on water hyacinth shoot growth and biomass under greenhouse conditions. The study site was located in Kibos at latitude 0⁰37’S and longitude 37⁰20’E with average temperature of 25 to 30⁰C and 22 to 27⁰C during the day and night respectively, and 60 to 69% relative humidity. Healthy water hyacinth plants were inoculated with the pathogens formulated in corn oil at 1x10⁹, 1x10⁸, 1x10⁷, 1x10⁶ and 1x10⁵spores/ml.  The control plants were not inoculated. The experiment was set up in completely randomized design (CRD) with each treatment replicated three times. At weeks 2, 4, and 6 after inoculation, the average shoot length and biomass for the treated basins were separately compared to the average shoot length and biomass of the control plants. Increase in spore density for both pathogens significantly increased relative shoot length and relative biomass.  Relative shoot length was 55.07 and 51.93 for C. piaropi and M. roridum respectively at 1x10⁹ spores/ml while relative biomass was 73.53 for C. piaropi and 37.60 at 1x10⁹ spores/ml. Inoculation suppressed shoot elongation and biomass with 1x10⁹ spores/ml being most effective. Cercospora piaropi formulated in corn oil lowered shoot length and biomass of water hyacinth more than M. roridum did.