Septoria musiva SO2202 v1.0 - Home. Septoria musiva (sexual stage: Mycosphaerella populorum) causes leaf spots and cankers on poplars (Populus spp. and hybrids).
On native North American poplars the pathogen mainly causes leaf spots that can lead to defoliation but generally do not kill the host. But S. musiva can also cause cankers on branches and primary stems. These can be lethal and are particularly severe on hybrid poplars in plantations. They often develop on the primary shoots of 2- to 3-year-old trees, leading to restrictions in the movement of water and nutrients and weakening the wood within a few feet of ground level.
The weakened trunks collapse easily, greatly reducing the production of biomass. Dendrome Project. TAIR - Home Page.