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Birch dieback is a disease of birch trees that causes the branches in the crown to die off. The disease may eventually kill the tree. In an event in the Eastern United States and Canada in the 1930s and 1940s, no causal agent was found, but the wood-boring beetle, the bronze birch borer, was implicated in the severe damage and death of the tree that often followed.
Betula nigra is a deciduous tree growing to 25–30 meters (80–100 ft) with a trunk 50 to 150 centimeters (20 to 60 in) in diameter. The base of the tree is often divided into multiple slender trunks. [2] [3] Bark. Bark characteristics of the river birch differ during its youth stage, maturation, and old growth.
Agrilus anxius, the bronze birch borer, is a wood-boring buprestid beetle native to North America, more numerous in the warmer parts of the continent and rare in the north. [1] It is a serious pest on birch trees (Betula), frequently killing them. The river birch Betula nigra is the most resistant species, while other American birches are less so.
These leaves usually fall before the normal leaves grow elsewhere on the tree. [3] There can be several witches broom in a tree. [4] Witches broom, formed by Taphrina betulina can be found on dwarf birch (Betula nana), Betula nana x pubescens, silver birch (Betula pendula), downy birch (Betula pubescens) and Betula pubescens var.glabrata. [1]
The disease gets its name from the black patches that grow on the trunks of infected trees. In a newly infected tree, branches become denuded and then die off. Eventually, the entire tree succumbs.
Despite this, the borers can still damage the trees if they are weakened by other means. Between about 1930 and 1950, many gray birch trees, along with paper birch and yellow birch (Betula alleghaniensis), were weakened by birch dieback disease, which allowed for the bronze birch borer to attack and kill the trees. [11]
A council wants to hear what people think about its plans to fight ash dieback in a woodland area.
Inonotus obliquus causes a white heart rot to develop in the host tree. The chaga spores enter the tree through wounds, particularly poorly healed branch stubs. The white rot decay will spread throughout the heartwood of the host. During the infection cycle, penetration of the sapwood occurs only around the sterile exterior mycelium mass. [4]