Are you worried about ailing poplars in your area or on your own property? Which diseases can be behind defoliated poplar crowns or bark proliferation and what you can do is explained below.
Poplar rust is easily recognized by the rust-like spots on the leaves
Main risk: fungal diseases
Poplars are most likely to be attacked by fungal diseases. Those that penetrate through the wood are summarized under the term tree canker or specifically poplar canker, although medically it is not real cancer. In addition, certain poplar species are also susceptible to other fungal diseases. In our latitudes relevant diseases in poplars are:
- bark burn
- poplar rust
- shoot tip disease
bark burn
Bark blight is caused by the sac fungus Csyptodiaporthe populea. It penetrates through cracks in the bark or through the leaf and bud scars of the poplar and initially causes spherical fruiting bodies of the fungus Discosporium populem, a subsidiary fruit of the trigger fungus, to form on the dead, one-year-old branches. Brownish, elliptical necrosis then appears on the bark. Also characteristic is the so-called treetop drought, i.e. a centrally concentrated dying of the crown twigs and branches. In older poplars, from the second year of disease, the main form of the fungus can form on the dead shoots.
Black poplars, aspens, white poplars and gray poplars are less affected by the risk of bark fire. To prevent this, you should choose a species that is less susceptible or not at all, such as the balsam poplar for your property. When cultivating, care must be taken to ensure adequate water supply. If the disease has broken out, affected twigs and branches must be cut out.
poplar rust
This fungal disease causes many small orange-yellow spores to appear on the top and bottom of the poplar. The fungal pathogen Melampsora populina multiplies massively via these. It overwinters on an intermediate host, for example on larches, arums, larkspur, dog's mercury or celandine in the vicinity.
In order to get rid of the poplar rust, this intermediate host must be identified and removed.
shoot tip disease
Symptoms of shoot tip disease are initially brownish spots on the young poplar leaves, which then shrink. When the fungus has penetrated the wood, the shoots turn dark and snap downwards like hooks. Since the pathogen overwinters in the affected parts of the plant, these must be cut out early and the fallen leaves must be disposed of.