Zusammenfassungen der Arbeitskreisbeiträge - Die DPG

A NEW AERIAL DISEASE OF EUROPEAN BEECH (FAGUS SYLVATICA): A
TWIG BLIGHT CAUSED BY SOILBORNE PHYTOPHTHORA SPP.
Nechwatal, Jan 1 ; Jörn Hahn 2 , Alexander Schönborn 2 , Gregor Schmitz 2
1
Bayerische Landesanstalt für Landwirtschaft, Institut für Pflanzenschutz, Lange Point 10,
85354 Freising, Deutschland
2
Universität Konstanz, Fachbereich Biologie, 78457 Konstanz, Deutschland
Contact: jan.nechwatal@lfl.bayern.de
During prolonged periods of rainfall in spring and summer 2010, blighted shoots and twigs of
European beech (Fagus sylvatica) were frequently observed in several beech stands in Southwestern
and Southern Germany. In most cases, long and short shoots of young understorey
trees or lower branches up to 1.5 m above the soil level were affected, but symptoms also
occurred regularly on twigs in heights up to 3 m above the ground. Usually the complete
current year’s shoot was damaged, and necrosis often also reached into the previous year’s
wood. From a large collection of symptomatic twigs Phytophthora plurivora and P.
cambivora were regularly isolated with ease from diseased necrotic bark and cambium
tissues. As these two species are generally considered to have a strictly soilborne lifestyle, it is
most likely that infective propagules are transmitted from the soil to above-ground parts of the
trees via rain splash. Accordingly, patterns of the disease in the field indicated that ponding
rain water in the stands or along forest roads promote the disease. In larger heights, however,
other vectors such as snails might be responsible for transmission. Although Phytophthora
spp. are well-known as causal agents of seedling blight as well as root and cambium rot or
aerial stem cankers of mature beech, to our knowledge this is the first report of a twig blight
in beech associated with soilborne Phytophthora spp. In particular in periods of high
precipitation, this disease might pose an additional threat to Central European beech forests,
endangering the future success of artificial and natural regeneration of beech.
PRESENCE OF RAMULARIA COLLO-CYGNI IN BAVARIA IN THE PAST 50
YEARS
Nyman, Marika 1 ;Michael Hess 1 , Hans Hausladen 1 , Stephan Weigand 2
1
Technische Universität München, Lehrstuhl für Phytopathologie, Emil-Ramann-Str. 2, 85354
Freising, Germany
2
Lfl, Institut für Pflanzenschutz, Lange Point 10, 85354 Freising, Germany
Contact: m.nyman@wzw.tum.de
Ramularia collo-cygni (Rcc) is a fungal pathogen of barley, causing Ramularia Leaf Spot
(RLS). Rcc was first described about 150 years ago, but has only recently become a problem
in barley production. In the past 10 years regular epidemics in Bavaria have significantly
reduced yield quantity and quality.
The importance of seed-borne transmission for the overall disease development in the field is
not yet known, but seed testing on material from seed archives gives the opportunity to see
how long the pathogen has been present in Bavaria. Investigations in England has shown that
the pathogen has co-existed with its host for a long time without causing major disease, but
unknown factors shifted the relationship to a host-pathogen one. Seeds from the Lfl archive
samples were screened by PCR.
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