Ascomata of L.nervata on underside of balsam fir needles. They are nearly black in color. Ascoma of Isthmiella faullii . It appears very similar to Lirula mirabilis . The three needlecast fungi on balsam fir all have a two-year life cycle and similar biology, including time of infection and symptom expression.
Annual infection can result in distinctly tricolor foliage.
The infected current-year foliage remains green, showing no symptoms until the following spring. Discolored needles may be shed or be broken off in the third year, or they may remain attached for a few years. Needles are infected individually and the fungus does not spread into the adjacent needles or the twig. The newly infected fir needles remain symptomless until the following spring when they begin to discolor. Infected needles then become pale and patchy green in color and slowly turn brown as they die.