Both substances reduced infestation with downy mildew mainly in the prebloom and bloom period.
Salicylic acid is a natural substance which is part of the defense mechanism of plants.
Phosphorous acid is an anorganic substance, that occurs naturally in plants, however in an extremely low dose. The objective of our investigations was to proof, whether these substances could help to replace or reduce the use of copper. In this experiment severe artificial primary infections caused an extreme spread of downy mildew. In 1999 different combinations of phosphorous acid and salicylic acid with copper and Mykosin were tested, also at Burg Wildeck research station. But afterwards disease rapidly attacked the leaves.