. Biology of rust resistance in forest trees : proceedings of a NATO-IUFRO advanced study institute, August 17-24, 1969. Trees; Pine; Trees; Rust diseases. 204 HOWARD B. KRIEBEL. Figure 3. An old stand of Virtus strobus on a recreation area in Adams County, Wisconsin (photo courtesy of the Wisconsin State Department of Agriculture). The principal destructive agent of P. strobus, other than blister rust, is the white pine weevil, Pissodes strobi (Peck). This insect kills the terminal shoot and deforms most trees in the Northeast (Fig. 4). It also does much damage in the Lake States and Canada b
. Biology of rust resistance in forest trees : proceedings of a NATO-IUFRO advanced study institute, August 17-24, 1969. Trees; Pine; Trees; Rust diseases. 204 HOWARD B. KRIEBEL. Figure 3. An old stand of Virtus strobus on a recreation area in Adams County, Wisconsin (photo courtesy of the Wisconsin State Department of Agriculture). The principal destructive agent of P. strobus, other than blister rust, is the white pine weevil, Pissodes strobi (Peck). This insect kills the terminal shoot and deforms most trees in the Northeast (Fig. 4). It also does much damage in the Lake States and Canada but is not a serious pext in the southern Appalachians (Kulman and Harmann, 1965) and the Midwest. Extensive planting of white pine in some areas where there is presently no problem could conceivably cause an increase in the weevil population and could result in widespread damage. The serious economic loss in northeastern white pine stands resulting from weevil attack has stimulated efforts to select and breed for resistance to weevil injury. Early results indicate that weevil-resistant white pines may be developed either through selection in P. strobus (Stroh and Gerhold, 1965) or by interspecific hybridization (Wright and Gabriel, 1959; Heimburger, 1963). Chiorotic dwarf is a disease common in young plantations throughout the midwestern and eastern United States. The cause is now known to be air pollution; the response is apparently genetically controlled (Dochinger and Seliskar, 1970). In pure stands, eastern white pine nearly always differentiates into a wide range of crown and diameter classes due to inherent variation in vigor (Deen, 1933). Because the species has a tendency to retain the lower branches after they die, pruning is necessary to obtain knot-free lumber (Fig. 1). Apical dominance is pronounced and unweeviled trees. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appeara
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Keywords: ., bookauthoruni, bookcentury1900, booksubjectpine, booksubjecttrees
