Peronospora hyoscyami f.sp. tabacina

Tobacco blue mold ( Peronospora hyoscyami f.sp. tabacina )

The tobacco blue mold ( Peronospora hyoscyami f.sp.. Tabacina, often also under the synonym Peronospora tabacina known) is a form of downy mildews ( Peronospora ) and is considered one of the most economically important diseases of the tobacco plant. The Eipilz originates from North America or Australia and was abducted internationally, in the years 1959 to 1961 he caused a momentous pandemic in Europe and the Orient.

Tobacco blue mold is Deutschlandund in many other countries, a notifiable disease, which begins on the lower leaves and continues upward. He needs for his development of a high humidity and moderate temperatures - due to resistance dangers the effectiveness of the fungicides used ( metalaxyl ) is monitored in Germany.

Features

The fungus is like all downy mildew species ( Peronosporaceae ) an obligate plant parasite and has branched conidiophores that contain the spores.

The symptoms of the disease are local swellings in young plants, lightening of the leaves and downward curled leaf margins. On the underside of leaves you can see a white fungus lawn from the mycelium of fungi. The leaves die off soon. In older plants, large, yellow to brown spots on the upper leaf surface to see. At the bottom of the sheet results in a blue-gray fungus lawn.

Way of life

In areas with mild winters, the fungus overwinters on tobacco plants, root sprouts or wild species. The conidia then pass over great distances in the spring with the help of wind and insects on the tobacco plantations. The spores are capable of germination for weeks. They penetrate after germination directly into the tissue. After eight days, then appear the typical spots.

Warm, moist weather favors the spread of the fungus very strong. With these conditions, it comes in rainy summers despite control measures to epidemic -like spread of the disease and thus also cause serious damage.

The fungus first infects different types of tobacco (Nicotiana ), but was annuum by other solanaceous plants such as eggplant (Solanum melongena ), Capsicum frutescens or Capsicum described.