Search

Development of sorghum downy mildew, incited by Peronoscleospora sorghi (Weston and Uppal) C.G. Shaw, on maize, sorghum and Johnson grass was investigated at two locations in Uganda during three seasons (1994 and 1995). More sorghum downy mildew developed on the Johnson grass and sorghum than on the maize at all locations and in all seasons. No significant differences were observed in sporulation of P. soghi on the three hosts. Leaf shredding occurred on the three hosts but was the least on maize. Cross-inoculation with both conidia and oospores was achieved on the three hosts. Since the fungal population formed oospores and sporulated readily on the three hosts, which is typical of the sorghum strain, the disease in Uganda is attributed to the sorghum strain. [ABSTRACT FROM AUTHOR]

Development of sorghum downy mildew (SDM), caused by Perenosclerospora sorghi (Weston and Uppal) C.G. Shaw, was monitored in three to five sequential plantings of six maize genotypes for three seasons in two locations in Uganda. Generally, incidence of SDM was not influenced by time of planting, suggesting that infection was initiated by oospores, the primary inoculum, and not conidia, the secondary inoculum. Genotype effects were highly significant (P<0.001); disease was high in Farida, Pool 16 and NZ 2, but low in Suwan 1. The six maize genotypes were grouped into three categories: resistant (Suwan 1), moderately resistant (102 and Longe 1), and susceptible (Farida, Pool 16 and NZ 2). Sporulation of P. sorghi varied significantly with the genotypes, being highest in the most susceptible genotype (Farida) and least on 102 and Longe 1. Suwan 1 was not tested for sporulation because of low infection. Thus, the resistant genotypes exhibited low incidence of SDM and low sporulation of P. sorghi . [ABSTRACT FROM AUTHOR]