Scleroderris

Scleroderris is a genus of fungi that includes several significant plant pathogens. The most well-known species is Gremmeniella abietina, formerly known as Scleroderris lagerbergii. This fungus primarily affects coniferous trees, particularly pines, spruces, and firs. It causes a disease known as Scleroderris canker, or brown spot needle blight.

The fungus typically infects young trees or the lower branches of older trees that are shaded and have high humidity. Symptoms include the browning and death of needles, often starting at the tip and progressing inwards. Cankers may form on the bark of twigs and branches, which can girdle and kill them. In severe infections, entire trees can die.

Scleroderris thrives in cool, moist conditions and is often associated with dense stands of young conifers. Spores are spread by rain splash and wind. Management strategies often involve silvicultural practices such as thinning dense stands to improve air circulation and reduce humidity. Removal and destruction of infected trees and branches can also help to limit the spread of the disease. In some cases, fungicides may be used, particularly in high-value plantations. The geographic distribution of Scleroderris canker is widespread, affecting forests in North America and Europe.