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Tittel: Sporulation of Bremia lactucae is affected by diurnal periodicity in combination with temperature and light
Forfattere:Nordskog, B., Gadoury, D., Seem, R. & Hermansen, A.
Navn på utgivelse: Abstract book, 8th Conference of the European Foundation for Plant Pathology & British Society for Plant Pathology Presidental Meeting 2006, Sustainable disease management: the European perspective, 13-17 August 2006, KVL, Fredriksberg, Denmark
Publikasjonstype: Proceeding fra int. konf. m. ISBN-nr
Side(r): 39 (P5.2)
Utgivelsesår: 2006
Avdeling: Bioforsk Plantehelse - Ås
Fagområde: Plantehelse og plantevern
Sammendrag: Light is a common component of forecasting models for downy mildews because its presence is assumed to suppress sporulation. Our objectives were to evaluate the effects of light intensity and quality, temperature, and diurnal periodicity on sporulation of Bremia lactucae, the causal agent of lettuce downy mildew. We found that the suppressive effect of light on sporulation was strongly dependent upon temperature; there was little suppression of sporulation by light at " 10 ºC. At temperatures where light suppressed sporulation, light in the range from 450-500 nm had the most suppressive effect, although a lesser effect of the wavebands from 450-500 nm was detected. At 15 ºC, a diurnal pattern of sporulation was observed independent of light and darkness. In current forecasting models, the time of sunrise and sunset are used to delimit the dark period when leaf wetness and high RH can induce sporulation. In Nordic countries the effects of short nights and extended twilight conditions should be incorporated into forecasting models. Also, since sporulation may be greatly reduced by light at temperatures above 15-20 ºC, this should be used to modify model predictions of sporulation during the time of day when sporulation can occur. The diurnal rhythm could interact with light and temperature to confound the results of controlled environment studies, and may be the controlling factor in timing of sporulation at low temperatures.