Sooty blotch of apple: Efficacy of different application strategies

Summary in the original language of the document

Sooty blotch causes heavy losses in Lake Constance organic apple production. In the last
five years research has been done at the research station for fruit growing
(Kompetenzzentrum Obstbau – Bodensee) on strategies to control Sooty blotch on organic
grown pome fruit. Different control strategies with lime sulphur, coconut soap and
potassium bicarbonate with different application rates, application times were tested in
several trials on the cultivar ‘Topaz’. Over the years the results show that lime sulphur has
significant effects in controlling Sooty blotch. In a first trial potassium bicarbonate showed
a promising efficacy against Sooty blotch. Concerning the right application times we need
further investigations. The problem is that Sooty blotch is a disease complex caused by
several fungi and it is likely that the fungi that are a part of the complex differ from area to
area.