Variation in pathogenicity and cultural characteristics of pyricularia grisea isolates from finger millet

Blast disease cauased by pyricularia grisea (Cooke) Sacc., is one of the major constraints limiting finger millet production in Uganda. This study characterized six representative isolatesof P. grisea obtained from the major finger millet growing districts of Uganda. Isolates were assessed with respect to their cultural variability and pathogenicity towards ten finger millet genotypes, six of which are popularly grown in Uganda. The pathogenicity of six isolates of P. grisea was tested on ten finger millet genotypes in the greenhouse, based on disease progress curve (AUDPC), lesion numbers, lesion expansion rates, apparent infection rates and sporulation intensity following inoculation. All isolates were pathogenic but their pathogenicity varied considerably and cultivar x isolate interactions were generally significant. Isolates from Mbale and Masindi(cool and wet areas) were most aggressive while isolates from Soroti and Arua (hotter environments) were least aggressive; the rest of the isolates were moderately pathogenic. th3e cultivars also reacted differently to P. grisea. However, Acc/100007, Acc/100008, Acc/100057 and Kat-Fm1 were very susceptible while P227, SX10, SX18-44 and Serere1 were resistant; the rest of the cultivars exhibited moderata reaction to P.grisea isolates.