Kraut- und Knollenfäule im Kartoffelanbau - ist im ökologischen Anbau eine wirksame Bekämpfung ohne Kupfer möglich?

Summary

In laboratory, growth chamber, micro-plot and small-plot field trials, 53 copper-free
preparations (CFPs) were examined for their potential to control potato late blight
(PLB) caused by Phytophthora infestans (PI). In-vitro, 43% of the CFP inhibited the
germination of sporangia or the mycelial growth of the pathogen completely. In growth
chamber trials, 21% of them reduced PI foliar blight of tomato seedlings by at least
80%. In contrast, in small-plot field trials with potatoes under practice like applications,
none of the CFPs sufficiently controlled the disease. Even in micro-plot field trials with
applications twice a week the efficacies did not exceed 60%. With in-vitro tests we
showed that the reason for the insufficient performance of the CFPs was due to their
lack of persistence and rainfastness. However, applications of copper fungicides with
low rates according to the decision support system Bio-PhytoPRE resulted in a good
control of late blight. We recommend using this strategy until CFPs are developed for
practise application.