Strategic irrigation against apple scab (Venturia inaequalis)

Research output: Chapter in Book/Report/Conference proceedingArticle in proceedingsResearch


In Denmark there are several organic orchards, that do not spray at all, and they seek non-spraying methods to prevent apple scab. In this pilot trial, irrigation with water at strategic moments was tested to prevent scab-infection. In April-June 2011 in five organic orchards we irrigated the orchard floor, to force the ascospores to be released. We irrigated with at least 0.2 mm of water in dry periods, at least 12 hours before rain forecast. The idea was to empty the stock of ascospores during dry spells, so they would dry out without infecting the leaves. To find the best strategic times for irrigation, we used the local weather forecast and the scab-warning programme Rimpro based on data from climate stations located in the orchards. In this first year of trial we experienced difficulties in spreading the water evenly. A water wagon turned out to work better than sprinklers. We found, that the irrigation did result in ascospore-release, but the effect on the scab-attack was not significant. We also experienced, that the fruit growers found this way of preventing scab very interesting and easy to carry out. The pilot-trial was financed by “Fonden for Oekologisk Jordbrug” and in 2011 it was conducted by the organic advisory-service. It is continued in 2012 and 2013 at the University of Copenhagen.
Original languageEnglish
Title of host publication15th International Conference on Organic Fruit-Growing : Proceedings to the Conference
Number of pages4
PublisherFoerdergemeinschaft Oekologischer Obstbau e.V. (FOEKO)
Publication date2012
ISBN (Print)978-3-98 04883-6
Publication statusPublished - 2012
Event15th International Conference on Organic Fruit-Growing - Universität Hohenheim , Stuttgart, Germany
Duration: 20 Feb 201222 Feb 2012


Conference15th International Conference on Organic Fruit-Growing
LocationUniversität Hohenheim

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