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BOWAS, A WEATHER- BASED WARNING SYSTEM FOR THE CONTROL OF BOTRYTIS
  • BLIGHT ('FIRE') IN LILY.
    BOWAS, A WEATHER- BASED WARNING SYSTEM FOR THE CONTROL OF BOTRYTIS
  • BLIGHT ('FIRE') IN LILY. JE VAN DEN ENDE, MG PENNOCK-VOS, CA BAST[AANSEN, ATHJ KOSTER AND LJ VAN DER MEER Bulb Research Centre, P.O. Box 85, 2160 AB Lisse, The Netherlands Background and objectives Fire, or Botrytis leaf blight caused by Botrytis elliptica is the most important foliar tel: 0252.462159 fax: 0252.417762 email: ernst.van.den.ende@agro.ibo.nidisease of ornamental lilies (Lilium sp.) in the Netherlands. Economic losses as a result of fire epidemics in lily vary from year to year. In experiments without fungicide control bulb yield reduction can be 20-50%. The potentially high rate of increase of an epidemic in combination with lack of curative control options, have induced risk-adverse control practices among dutch lily bulb growers. Most growers spray on a weekly base with protective fungicides from the start of the season in april until harvest in oktober to control the disease, amounting to an input of active ingredients of approximately 25-40 kg/ha per year. Our aim was to develop a warning system for the control of Botrytis leaf blight in lily (BoWaS) in order to optimize the present control strategy and to reduce the amount of fungicides used in lily bulb growing. Materials and methods Infection of lilies by B. elliptica was studied under different temperature and humidity conditions[l]. BoWaS uses data from these studies and the regional forecast of the weather variables 'leaf wetness duration' and 'leaf temperature' to predict critical periods for Botrytis infection in lily for a five day period ahead. Critical periods and hence action thresholds depend on cultivar susceptibility[2]. Between 1994 and 1997 the warning system was tested in several lily cultivars grown at different locations. Results and conclusions Results showed that a 30-80% reduction of input of active ingredients could be achieved depending on the cultivar susceptibility and year. On farm testing of BoWaS verified the results from our research. In 1998 BoWas will be available for the commercial lily growers. References 1. Doss RP, Christian JK, Chastagner GA, 1988. Canadian Journal of Botany 66, 1204-1208 2. Bastiaansen C, Koster ATHJ, VanderMeer LJ, VandenEnde JE, Pennock I, Buurman FPM, 1997. Acta Horticulturae 430, 657-660