A study of several aspects of the associations between endophytic fungi and conifers

Endophytic fungi from balsam fir (Abies balsamea (L.) Mill.) and black spruce (Picea mariana (Mill) B.S.P.) needles were investigated.;Fungal isolates were obtained from dormant balsam fir buds and needles. Only three isolates were obtained from 400 buds. A total of 111 isolates was obtained from needles of four age classes collected over 18 weeks between May and September, 1989 inclusively. Ten different fungal taxa were found and four of these (Phyllosticta sp., black yeast, Leptostroma sp. and Cryptocline abietina Petrak) accounted for over 80% of all isolates. An increase in the number of isolates was noted with sampling date, increased needle age and from basal segments.;The interiors of dormant and newly-flushed buds of black spruce were virtually fungus-free (1 isolate from 400 buds). Isolates were obtained from the basal segments more frequently compared to mid or tip segments. Fungal isolation rates increased during the sampling period and from 4% in current-year needles to 90% in three-year-old needles.;From the collection of 914 isolates, 21 (from 100 randomly selected) produced compounds which negatively affected spruce budworm cells. Isolates which rendered toxins were from needles from four age classes (0-3 years), from all needle segments and from needles collected on each sampling day. Five isolates increased larval mortality when fed as hyphae to second instars and seven increased mortality when fed as extracts. Instar development and dry body weights were also affected in hyphal assays whereas only body weights were affected in extract tests. In some cases the effect was to accelerate development and increase dry body weight. (Abstract shortened by UMI.).;Black spruce seedlings (3 cm) were inoculated with two needle endophytes (XW and Aureobasidium pullulans) from black spruce and one (Phyllosticta sp.) from balsam fir. Hyphae were observed on shoot surfaces and in stomatal areas. Micrographs revealed colonization of stomata. Colonization success of shoot interiors ranged between 32% and 59%.