Co-occurrence of the ascomycete Lophodermium piceae and the rust fungus Chrysomyxa abietis in Norway spruce needles

The frequency of needles and the proportion of needle segments infected by Lophodermium piceae were compared in symptomless and Chrysomyxa abietis-inf ected, 1-year-old needles of Picea abies. In late spring, symptomless needl es from both rust-infected and healthy saplings were sampled. In addition, rust-infected, totally chlorotic needles and needles with chlorosis along a bout half their length from the diseased trees were examined. In all three stands, the proportion of segments infected by L. piceae was larger in the rust-infected half of the needle than in the symptomless half; but the diff erence was statistically significant in only one of the stands. The proport ion of L. piceae-infected segments among the nonrust-infected needles was t he same as that found for the uninfected half of rust-infected needles (aft er correction for size differences). No differences in the proportion of L, piceae-infected segments were found between the totally chlorotic, rust-in fected needles and the green needles of diseased or healthy trees.