EFFECTS OF LOW-TEMPERATURE ON MYCELIAL GROWTH AND SPORE GERMINATION OF BOTRYTIS-ALLII IN CULTURE AND ON ITS PATHOGENICITY TO STORED GARLIC BULBS

Botrytis allii was incubated at 20, 10, 4, 2, 0, -2 and -4 degrees to investigate effects of temperature on growth, sporulation and germinat ion on potato dextrose agar (PDA), and to estimate incidence and sever ity of disease on garlic bulbs inoculated with the pathogen during sto rage. B. allii was capable of growing to a colony diameter of 17 mm af ter 20 weeks, sporulating and germinating on PDA at temperature as low as -4 degrees C. After 12 weeks at -4 and -2 degrees C the mycelial g rowth was observed only on 45-54% of bulbs wound-inoculated with conid ial suspension, and infection was limited to 5 mm in diameter on the s urface of inoculation sites without producing any symptoms of the dise ase. Temperature responses were similar for mycelial growth, conidial germination and infection, but mycelial growth and sporulation was slo wer and later on garlic bulbs than in culture. Wounds were readily col onized by B. allii. No disease was found on unwounded bulbs that were inoculated with conidial suspensions and with mycelial plugs at variou s temperatures. Only 1 . 6-9 . 5% of cloves became infected by contact with other cloves within the same bulb after 12 weeks of storage at t emperatures of 4-20 degrees C.