Distribution of foliar fungal endophytes of Pinus strobus between and within host trees

The distribution of foliar fungal endophytes within and between needles and trees of Pinus strobus L. (white pine) is largely unknown. In this study, needles were collected in Muskoka, Ontario, plated, and scored for hyphal o utgrowth of endophytes to observe distributional patterns. Individual trees displayed different levels of infection but branches within those trees ha d similar levels. There was a large difference in the infection levels betw een the two extant needle age-classes, with the youngest needles being virt ually endophyte-free. Needles divided into four sections exhibited the most hyphal outgrowth from the distal portion and the least from the medial-pro ximal portion. Cultural morphotypes were primarily of the Lophodermium and Hormonema morphologies. Lophodermium occurred at all positions along the ne edle but Hormonema was restricted to the proximal and distal portions. Infr equently occurring fungi of diverse morphotypes were found at all four need le positions. A separate experiment compared levels of endophyte infection between Muskoka trees and trees growing in an urban area (Guelph, Ontario). Needle pieces from Guelph hosts had low rates of infection (0.02%) compare d with needle pieces from Muskoka hosts (66.5%). Thus, for white pine, foli ar endophyte distribution is patchy within and between needles, trees, and locations, possibly reflecting differences in microhabitat or infection suc cess.