Birch trees are susceptible to a variety of fungus problems that primarily attack foliage, leading to the potential cosmetic destruction of your home garden trees. Serious injury may also occur, so get to know what to look for and how to respond should a fungal infection occur in your home landscape.
Healthy birch trees are more likely to resist or overcome fungus infection problems when kept vigorous. Grow birch trees in locations that offer full sunlight to partial shade. Birch trees thrive in moist soil with cool temperatures, according to Northeastern Area State & Private Forestry.
Anthracnose is a fungus that affects birch trees. Cause by a variety of fungi, anthracnose affects birch foliage, according to the University of Missouri Extension. Leaf rust is another fungus problem of birch trees, caused by the fungus Melampsoridium betulinum, which attacks leaves, according to the University of Maryland Extension. Both anthracnose and leaf rust attack the birch tree most prevalently during the spring and fall seasons.
In cool, moist conditions, anthracnose germinates and infects birch trees. During infection, look for small, abnormally shaped, roundish spots with dark brown borders on plant surfaces, according to the University of Missouri Extension. This disease results in premature leaf drop and dieback of tree branches. Due to injury, birch trees often experience diminished health. Leaf rust on birch trees results in the display of powder-like growths on the undersides of leaves in vivid yellow-orange hues, according to the University of Maryland. The top sides of leaves experience brown leaf spots with yellow halos. The expansion of infection leads to leaf drop.
Natural control is recommended for anthracnose on birch trees, as fungicides are generally only suggested for ash trees, according to the University of California IPM Online. With that in mind, to control anthracnose on birch, collect and destroy affected plant parts, particularly plant debris upon which fungi overwinter. Thin your birch tree for optimal air circulation, according to the University of Missouri Extension. For leaf rust fungus on birch, employ the same method of removal and destruction of infected plant parts, according to the University of Maryland Extension.
As chemical controls are not recommended for anthracnose on birch, maintain healthy, vigorous trees. However, chemical control is available for leaf rust on birch. At budbreak, while leaves are expanding during the spring season, apply a chemical with a copper-based active ingredient, according to the University of Maryland Extension. Although this may not provide a cure for the leaf rust, it will reduce the intensity of the infection.