Calcium Enhanced Zoospore Production of Pythium myriotylum in vitro

Pythium myriotylum is the causal organism ofCocoya m Root Rot Disease (CRRD). Significant numbers of zoospores were induced within 1.5 h in cultures in Petri dishes containing P. myriotylum soaked in 0.01 M Ca++ and sterile deionized distilled water. Soaking solutions # 2 and # 3 inhibited the production ofzoospo res of P. myriotylum. This may be due to the delay in maturation ofsporangi a and the release of zoospores when the soaking solutions contain sucrose. Significant necrosis ofdetached cocoyam plantlet roots in 100 ml beakers confirmed the infection ofzoosp ores oftwo ‘local white’ cocoyam genotypes. Detached ‘yellow’ cocoyam roots in 100 ml beakers ofgenotype RO3015 resisted infection of P. myriotylum with no necrosis of the inoculated roots, which may indicate resistance. This provides a quick and reliable pathogenicity test of P. myriotylum on susceptible cocoyam detached roots. Necrosis ofinocu lated detached cocoyam roots could be reliably used to screen cocoyam germplasm for resistance to P. myriotylum.