Tobacco blue mold
| Tobacco blue mold | ||||||||||||
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Tobacco blue mold ( Peronospora hyoscyami f.sp. tabacina ) |
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| Scientific name | ||||||||||||
| Peronospora hyoscyami f.sp. tabacina | ||||||||||||
| Skalický (1964) |
The tobacco blue mold ( Peronospora hyoscyami f. Sp. Tabacina , often also known under the synonym Peronospora tabacina ) is a form of downy mildew ( Peronospora ) and is one of the economically most important diseases of the tobacco plant . The egg fungus originally comes from North America or Australia and was transported internationally, whereupon it caused a momentous epidemic in Europe and the Orient from 1959 to 1961 .
Tobacco blue mold is a reportable disease in Germany and many other countries that begins on the lower leaves and continues upwards. It needs high humidity and medium temperatures for its development - due to the risk of resistance , the effectiveness of the fungicides used (e.g. Metalaxyl ) is monitored in Germany.
features
Like all downy mildew species (Peronosporaceae), the fungus is an obligatory plant parasite and has branched conidia carriers that contain the spores .
The symptoms of the disease in young plants are local bulges, lightening of the leaves and leaf edges that are rolled down. On the underside of the leaf you can see a white mushroom lawn from the mycelium of the mushrooms. The leaves soon die off. In older plants, large, yellow to brown spots can be seen on the upper side of the leaves. A gray-blue mushroom lawn develops on the underside of the leaf.
Way of life
In mild winter areas, the fungus overwinters on tobacco plants, root shoots or wild species. The conidiospores then reach the tobacco plantations over great distances in spring with the help of wind and insects. The spores can germinate for weeks. They penetrate directly into the tissue after germination. The typical spots appear after eight days.
Warm, humid weather strongly encourages the fungi to spread. With these conditions, in rainy summers, despite control measures, the disease spreads like an epidemic and thus causes severe damage.
The fungus mainly attacks various types of tobacco ( Nicotiana ), but has also been described by other nightshade plants such as the aubergine ( Solanum melongena ), Capsicum annuum or Capsicum frutescens .
Individual evidence
- ↑ Species entry in the index fungorum
- ↑ Schmiedeknecht 200, page 387
- ^ Ordinance to combat blue mold in tobacco (BlauSchimmelV 1978)
- ↑ Fungicide tolerance in isolates of Peronospora tabacina (PDF; 301 kB)
literature
- Martin Schmiedeknecht: Order false powdery mildew, Peronosporales in: Urania plant kingdom. Viruses, bacteria, algae, fungi. Urania-Verlag, Berlin 2000; Pages 383-387 ISBN 3-332-01167-7