Larch needle cast
Damage, symptoms and biology
This disease does not kill large trees, but repeated infections can result in growth reduction.
This fungus generally kills the needles and secondary short shoots.
Needles affected by this disease suddenly turn yellow and then red-brown in the spring and early summer and infected needles are generally shed soon after they turn brown.
The rapid onset of disease symptoms could be confused with frost damage. Frost damage, however, tends to kill both needles and young stems, and no fruiting bodies are formed. Several rust fungi including Melampsora occidentalis, M. albertensis, and M. paradoxa Diet. & Holw. are also found on larch. These can be distinguished by their spore-producing fruiting structures (aecia).