Betula pubescens planted trees, while naturally regenerated trees seem less susceptible. This disease also affects "Betula pendula" and in 2000 was reported at many of the sites planted with birch in Scotland during the 1990s. The outer layer of bark can be stripped off the tree without killing it and can be used to make canoe skins, drinking vessels and roofing tiles. The inner bark can be used for the production of rope and for making a form of oiled paper. This bark is also rich in tannin and has been used as a brown dye and as a preservative. The bark
Citrus gummy bark viroid Citrus gummy bark viroid The citrus gummy bark viroid (abbreviated CGBVd) is a sub-species of the hop stunt viroid, and thus is a member of the genus Hostuviroid. As the name suggests, the citrus gummy bark viroid causes problems in the bark of the sweet orange tree. Scrapping the bark exposes localized spots or a line of reddish-brown, gum-impregnated tissue around the scion circumference especially visible near the bud union. The discoloration and gumming may extend above the bud union to the main branches of the sweet orange while in severe infection dark streaks of gum-impregnated tissue may also be