Comandra blister rust
Damage, symptoms and biology
Trees of all sizes and ages are affected, and the presence of cankers can result in growth defects and mortality. Outbreaks of this disease are sporadic, due to variations in the distribution of the alternate host and the periodicity of environmental conditions necessary for infection. The most serious damage has been observed in nurseries and plantations where rapid stem girdling results in high mortality.
A large numbers of galls reduces the aesthetic appearance and value of ornamentals and Christmas trees.
The aecial cankers of comandra blister rust are very similar in appearance to those of sweet-fern and stalactiform rusts. However, examination of the uniquely shaped aeciospores with a microscope or even a hand-lens will distinguish this rust from others. Swellings on seedlings might be confused with pre-sporulating gall of Endocronartium harknessii; however, C. comandrae swellings result from swollen bark, while E. harknessii galls have normal bark over abnormally thickened xylem tissue.
Canadian Forest Service Publications
Information on host(s)
Mugho pine, pitch pine, scots pine