Control of <Emphasis Type="Italic">Botrytis cinerea</Emphasis> in glasshouse fuchsia by specific climate management

The effect of climate management as a tool for integrated control of Botrytis cinerea in fuchsia culture was studied in two glasshouse experiments. This included: (i) a conventional, temperature based (T) and (ii) a humidity/temperature based (HT) climate control. When neighbouring plants came in contact with one another, a novel, economical method of direct ventilation of the canopy was employed as an additional treatment in each glasshouse. Despite significant differences in plant growth, no distinct effects on the susceptibility of clonal fuchsia plants or on the growth rate of stem blight lesions within the canopy were found for the different climate managements. Using the HT strategy, the canopies were effectively dehumidified during the night in contrast to the T management. Towards the end of the cultivation, a period with dense canopies, direct ventilation was most effective in dehumidifying the canopy. The differences in microclimate were correlated with B. cinerea stem infection and sporulation incidence. Best results were achieved using a combination of the HT strategy with direct ventilation, reducing stem blight values to less than a third as compared to the T management. With regard to plant health, climate management in glasshouses can only be improved by specific manipulation of the canopy climate: in presence of susceptible plant tissue, a management providing vapour pressure deficit values within the canopy above 1 hPa, or more safely, 1.5 hPa, is recommended.