Co-Authors:
Yunis, H.
Shtienberg, D.
Elad, Y.
Mahrer, Y., Department of Plant Pathology, Agricultural Research Organization, The Volcani Center, Bet Dagan, 50250, Israel, Department of Soil Sciences, The Hebrew University of Jerusalem, Faculty of Agriculture, Rehovot, 76100, Israel
Abstract:
Disease records and microclimatic parameters were analysed in order to develop a model for predicting outbreaks of grey mould (Botrytis cinerea) epidemics in non-heated cucumber greenhouses. A quantitative statistical approach failed to produce a reliable model. However, when employing a qualitative approach, an accurate, biologically sound prediction model was developed. Outbreaks of grey mould occurred when, on a weekly average, the wetting period of the foliage exceeded 7 h day-1 and the duration of temperature in the range of 9-21°C during the night (18:00-08:00) exceeded 9.5 h day-1. Data recorded in two growing seasons were used to construct the model and its predictions were evaluated with an independent data set. Controlled-environment experiments provided biological interpretations for these greenhouse-originated thresholds: when free moisture was present, germination of B. cinerea spores occurred within 7 h; the period during which the pathogen is exposed to environmental microclimatic influences (germination and penetration) is 9-10 h. The potential for outbreaks of grey mould epidemics in commercial greenhouses could be reduced by restricting the wetting period to <7 h day-1 by measures such as ventilation and heating. © 1994.