Canadian Forest Service Publications
Effects of infestation by the balsam woolly aphid, Adelges piceae (Ratz.) on the ultrastructure of bordered-pit membranes of grand fir, Abies gradis (Dougl.) Lindl. 1971. Puritch, G.S.; Johnson, R.P.C. Journal of Experimental Botany 22(4): 953-958.
Issued by: Pacific Forestry Centre
Catalog ID: 28407
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The ultrastructure of bordered-pit membranes in normal grand fir trees, Abies grandis (Doug.) Lindl., was compared with that in trees infested with the blasam woolly aphid, Adelges piceae (Ratz).
In sapwood of non-infested trees the membranes of earlywood pits were well perforated, whereas those of latewood pits were either heavily incrusted or incompletely developed and showed few perforations. In the heartwood pit membranes from both earlywood and latewood were heavily incrusted.
In aphid-infested trees all the pit membranes from the sapwood were incrusted and resembled those from heartwood of non-infested trees. These incurstations reduced the number of pores in the margo of pit membranes, and could account for the reduced permeability to water reported for sapwood trees attacked by the aphid. We suggest that the incrustation of pit membranes in sapwood in Abies grandis infested with Adelges piceae occurs because these aphids cause heartwood to form prematurely.