EFFECTS OF THE PRODUCTION ENVIRONMENT ON THE SUSCEPTIBILITY OF ROSE FLOWERS TO POSTHARVEST INFECTION BY BOTRYTIS-CINEREA

We studied the effects of environmental conditions during production o n susceptibility of roses to postharvest infection by B. cinerea. For flowers harvested from a commercial greenhouse, susceptibility was lin early correlated (r = 0.97) with mean air velocity during the 5-week p eriods before each harvest, Susceptibility was also correlated with me an leaf to air temperature gradient (r = 0.83) and inversely correlate d with wetness measured on an electronic leaf (r = -0.92), but these c orrelations mere interpreted as secondary effects of the correlation w ith air movement, Susceptibility was not correlated with temperature, relative humidity (RH), or the other factors measured. In growth chamb er experiments, flowers grown under high wind speed (0.55 m . s(-1)) w ere significantly more susceptible to infection than flowers grown und er low wind speed (0.18 m . s(-1)). High relative humidity during prod uction increased background infection levels (i.e., those infections n ot caused by laboratory inoculation) but did not affect susceptibility .