Diseases and pests in intensive onion growing
1989
Krauthausen, H.-J. (Bezirkspflanzenschutzamt Pfalz, Neustadt/Weinstrasse (Germany, F.R.))
In intensive onion growing in the Rhine Valley a number of diseases cause serious problems. Botrytis squamosa leaf blight largely reduces yield every year. Therefore it is necessary to grow less susceptible cultivars and to apply several fungicide sprayings. Euparen (Dichlofluanid), the only registered fungicide for onions in the FRG, as well as Ronilan (Vinclozolin) and Rovral (Iprodion) proved effective in controlling the disease. First analyses show low residue values of these dicarboximides. Downy mildew (Peronospora destructor) and onion white rot (Sclerotium cepivorum) can also cause extensive damage. Ridomil TK (Metalaxyl + Mancozeb) respectively Bayfirdan (Triadimenol), Folicur (Ethyltrianol) or Sumisclex (Procymidon) fight the aforementioned diseases. So far there have not been any tests concerning residue values for these applications. Apart from diseases Thrips tabaci also leads to large yield losses
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