New Zealand Plant Protection 69 (2016): 319
Different freezing and melting conditions of conidial suspensions of Neonectria ditissima were examined to determine optimal long-term storage conditions. Four concentrations of glycerol, two freezing temperatures and three melting methods were compared, using two isolates, RS305p with single-celled conidia and RS324p with multi-celled 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 -80°C had significantly higher germination rates than those at -20°C. Defrosting in a 20°C water bath resulted in significantly higher germination rates than defrosting in ice water. However, freezing for 10 months at -80°C 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.
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