Major Leaf Spot Diseases Of Barley And Their Control Using Fungicides
Barley leaves exhibiting disease symptoms were collected from Kenya Breweries experimental plots in Mau Narok and Naivasha. Two barley foliar fungal pathogens, Rhynchcsporium secalis Oud and Bipolsris sorokinienum Sorok were isolated and characterised. Comparisons of conidia obtained from pathogenecity tests showed that the morphology of the conidia produced on seedling leaves were similar to those used in the inoculum. The sensitivity of R. secalis and B. sorokinianum to five fungicides namely Carbendazim, Propiconazole, Frutriafol, Triadimenal and Prochloraz were tested on fungicide amended media and slide germination tests. ED 50 values (dose for 50 percent inhibition) were calculated from the dose response curves R. secalis showed no growth on .agar amended with Prochloraz at all the concentrations used. while Carbendazim and Propiconazole showed superior efficacy over Frutriafol and Triadimenal. ED 50 for the four fungicides was as follows after a three week period: Carbendazim, 3.9 ppm; Propiconazole, 14.2 ppm; Frutriafol, 239.8 ppm and Triadimenal, 271.7 ppm. With B. sorokinianum all the five fungicides used were active in inhibiting mycelial growth, Their ED 58 were as follows after ten days of incubation; less than 50 ppm for Carbendazim and Propiconazole; Frutriafol, 50 ppm; Triadimenal, 125 ppm and Prochloraz 3.125 ppm. Of all the fungicides tested, none gave complete inhibition of conidial germination of B. sorokinianum although however they were active with their ED 50 as follows: 103 ppm Carbendazim; 80.8 ppm Propiconazole; 125 ppm Frutriafol; 117.1 ppm Triadimenal and 62.4 Prochloraz, The ED 50 for germtube inhibition were; Carbendazim, Propiconazole and Prochloraz lower than 50 ppm; Frutriafol 108.23 ppm and Triadimenal 95.6 ppm. The fungicides . inhibited germtube elongation much more than conidial germination.