mildew
Powdery mildew is a collective name for various plant diseases caused by fungi , which usually appear as a white coating (fungal lawn) on leaf surfaces. A distinction is made between real and downy mildew species .
Powdery mildew
To the sac fungi belonging (Ascomycota) pathogen of powdery mildew (Erysiphaceae) attack primarily leaves. These are first covered with a flour-like coating, later they turn brown and dry up. The real powdery mildew fungi include u. a. the grass powdery mildew ( Blumeria graminis ), which affects cereals and grazing grasses, and the grapevine powdery mildew ( Erysiphe necator ).
Powdery mildew overwinters in small spore housings on the plant or as mycelium, e.g. B. on the bud scales of fruit trees or on the branches, also on weeds. Dry weather favors the spread (fair weather mushroom), as well as humid and warm weather and the strong temperature difference between day and night in autumn. A humidity of 70 percent is sufficient for the spores, as they are supplied with nutrients and water by default. A temperature of around 20 ° C is ideal for spreading.
Wrong mildew
The downy mildew (Peronosporaceae) pathogens belonging to the egg fungi ( Oomycota ) usually penetrate deeper into the plant and often create a whitish coating on the underside of the leaves. Important plant parasites are downy mildew of wine ( Plasmopara viticola ), blue mold of tobacco ( Peronospora tabacina ) and the also relatively host-specific Phytophthora species. The downy mildew of lettuce ( Bremia lactucae ) has also become relatively well known through resistance breeding with the help of poison lettuce .
gallery
Powdery mildew on phlox; slight colonization with visible mycelia foci
Powdery mildew, fully populated leaf and plant parts
Powdery mildew, fully populated leaf (enlarged)
Powdery mildew, fully populated leaf at high magnification
Combat
On phlox ( Phlox paniculata ) powdery mildew is found in veritable amounts in many gardens these days. Fungicides of various chemical structures are used in agriculture and horticulture to combat the various types of mildew (e.g. tridemorphs ). For example, sulfur- based pesticides are widespread against powdery mildew, which predominantly grow on the leaf surface .
As a food source within intact ecosystems , powdery mildew is vital for some species of ladybirds . So eat z. B. the sixteen - spotted and twenty-two- spot ladybug exclusively from powdery mildew.
literature
- Friedemann Klenke, Markus Scholler: Plant Parasitic Small Mushrooms: Identification book for fire, rust, powdery mildew, flagellate fungi and usury relatives in Germany, Austria, Switzerland and South Tyrol , published by the Museum für Naturkunde (Berlin) , Springer, Berlin 2015, ISBN 978- 3-642-55330-1 .
Web links
Individual evidence
- ↑ a b c Plant diseases and pests. In: Meyers Taschenlexikon AZ. 6th edition, BI-Taschenbuchverlag, Mannheim 2002, ISBN 3-411-10136-9 , pp. 529-530.