Verticillium wilt
The verticillium wilt is a woody plants concerned plant disease caused by fungi of the genus Verticillium is caused. The two species Verticillium dahliae and Verticillium albo-atrum attack over 350 horticultural and agricultural host plants (with over 70 tree species and shrubs), with Verticillium dahliae in particular appearing on many woody plants with symptoms of "wilting". Both Verticillium species are soil-borne pathogens.
The wilt fungus is often introduced into the soil on a large scale when new plantings are made. The most important host plant in practice is the maple ( Acer ; including Norway maple , Japanese maple ). It is followed by species of the genera Catalpa , Cornus , Clematis , Castanea , Fraxinus , Robinia and Aesculus and many other woody genera . Less susceptible are u. a. Alder , poplar , plane , birch , hornbeam and red beech . Small-pored trees such as maple are significantly more susceptible than large-pored ones, as the guide vessels remain functional for a long time and are not replaced with new ones every year. Monocot plants and conifers are not attacked.
diagnosis
The fungus can be recognized by the following symptoms : Shoots that z. B. have sprouted again in spring after winter, suddenly show withered leaves, although the plants are sufficiently watered and fertilized. The previously green, firm leaves turn pale green and floppy.
On thicker dead branches you can tell from the bark that it is getting "scratchy" and is no longer smooth. Furthermore, in the section of a thick branch in the wood, a small crescent-shaped crescent can be seen. This indicates that the fungus has already grown deep into the wood and continues to grow even after it has been cut back .
Combat
Usual spraying against fungi on the leaves of the plants has no effect, as the fungus is protected inside the branches. A certain reduction in the symptoms of damage can usually only be achieved temporarily. Cut parts of the plant must not be chopped on the compost or chopped, as the fungus is highly infectious and can be spread through the compost.
Potentially infected secateurs, saws and other garden tools must be disinfected (e.g. flamed) after use.
The only way to get the fungus out of an area would be a profound soil exchange, which is often not possible because then all plants would have to be removed and destroyed because of the adhering soil. Lowering the pH of the soil can reduce the risk of infection.
resistance
According to the plant protection office , the following deciduous trees are resistant to the fungus: walnuts ( Juglans ), willows ( Salix ), oaks ( Quercus ) and pears ( Pyrus ).
In the event of an infestation, the conifers that are insensitive to this fungus can also be replanted, e.g. B. in hedges made of yew ( Taxus baccata ) or thuja .
literature
Horst Börner: Plant diseases and plant protection . 8th edition. Springer, Berlin / Heidelberg 2009, ISBN 978-3-540-49068-5 .
Individual evidence
- ↑ Arbofux: Verticillium wilt on deciduous trees. Retrieved August 13, 2015 .
- ↑ Berlin Plant Protection Office : Verticillium wilt on woody plants. Retrieved August 13, 2015 .