Freezing and melting conditions affect the viability of Neonectria ditissima conidia

Different freezing and melting conditions of conidial suspensions of Neonectria ditissima were examined to determine optimal longterm storage conditions Four concentrations of glycerol two freezing temperatures and three melting methods were compared using two isolates RS305p with singlecelled conidia and RS324p with multicelled conidia After 10 months conidia of RS305p had significantly higher germination rates than those of RS324p Glycerol added to conidial suspensions before freezing reduced the germination rate significantly Suspensions frozen at 80C had significantly higher germination rates than those at 20C Defrosting in a 20C water bath resulted in significantly higher germination rates than defrosting in ice water However freezing for 10 months at 80C without glycerol reduced the conidial germination rate of RS324p from 65 before freezing to 8 In contrast the conidial germination rate of RS305p frozen in the same conditions increased from 15 to 74 More research is needed to determine optimal storage conditions