Effect of Temperature During Conidial Formation of Monilinia laxa on Conidial Size, Germination and Infection of Stored Nectarines

Conidia of Monilinia laxa produced at di}erent tem! peratures were studied for size and germinability\ and for their pathogenicity to nectarine fruits kept in refrigerated storage at 9>C[ The mycelial growth\ which was evaluated on peach!agar at temperatures ranging from 14 to 3>Cdecreased with temperature and ceased at 3>C[ When the temperature was lowered from 14 to 9>C\ the conidia volumes increased by 30) on peach!agar and by 04[4) on nectarines[ The conidia germinated at the tem! peratures tested from 19 to 3>C[ At germination tem! perature from 09 to 3>C\ larger conidia produced at 9 and 4>C germinated earlier with longer germ tubes than those produced at 14>C[ But when incubated at 19>C the conidia produced at 9>C germinated later or at the same time as those produced at 14>C and formed shorter germ! tubes[ Conidia produced at the lower temperatures "9 and 4>C# and inoculated onto wounded nectarines stored at 9>C\ were highly infective and infectivity decreased when the conidia were produced at 14>C[ The di}erences were particularly evident at the lower conidium sus! pension concentration "4 091 and 1 092 conidia ml 0#[ After 3 weeks 29 49) of the nectarines had rotten when the inoculation was carried out with spores at the concentrations of 4 091 and 1 092 conidia ml 0 and produced at 9>C\ while the fruits infected with spores produced at 14>C were all still sound