Net blotch disease on winter barley (Drechslera teres, perfect stage: Pyrenophora teres), disease progress and threshold for fungicidal treatments
1990
Brandl, F. (Technische Univ. Muenchen, Weihenstephan (Germany, F.R.). Lehrstuhl fuer Phytopathologie) | Hoffmann, G.M.
The progress of net blotch disease (Drechslera teres, perfect stage Pyrenophora teres) was recorded in field at three locations in Bavaria during 1985 and 1986 by weekly datas of the development of symptoms on different leaf levels. A rapidly increase of the disease occurred under stimulating weather conditions over several leaf levels between the plant growth stages EC 32 and EC 37/39. On the basis of the effects of fungicidal treatments at different epidemiological situations with Propiconazol, Prochloraz and Tebuconazol a first threshold could be recommended with 1 per cent BCN (leaf-chlorosis-necrosis) from EC 32 on leaf F-3 (F = flag leaf) or higher leaf levels in later stages. Under higher infection rates double treatments within a short interval are necessary. The high potency of yield-decreasing of the disease till 40 per cent could be confirmed together with the efficacy of well timed and most favourable fungicidal treatments (netto yields over 400 DM/ha). The datas are discussed from the viewpoint of an integrated pest management considering epidemiological aspects and disease thresholds
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