Branch and tip blights.

Abstract

In the temperate zone, the main agents causing damage to forest tree crowns, with the exception of abiotic agents and insects, are the Ascomycota, followed by the rust-causing Basidiomycota. This chapter will mainly focus on Gremmeniella abietina, Diplodia pinea (syn. Sphaeropsis sapinea), Sirococcus conigenus and Venturia populina, which are among the best known agents of serious epidemics on conifers and on poplars (Populus spp.). Information is given on the pathogen distribution, host range, detection, infection biology and epidemiology. Some of the most important environmental factors and anthropogenic activities affecting the incidence of crown diseases are mentioned. Several management strategies and tactics are described, which include chemical control measures, systemic induced resistance, genetic resistance and cultural practices.