. Response of dwarf mistletoe-infested ponderosa pine to thinning. Dwarf mistletoes; Ponderosa pine Diseases and pests; Ponderosa pine Thinning. Discussion and This study indicates that, for at least a decade, moderately infested stands of Application sapling-sized ponderosa pine thinned to 250 trees per acre will produce as much wood as healthy stands thinned to the same density. This is not a new idea, because Shea (1964) and Belluschi (Shea and Belluschi 1965), working with indi- vidual tree growth rather than per acre wood production, found significant reductions in diameter growth only in
. Response of dwarf mistletoe-infested ponderosa pine to thinning. Dwarf mistletoes; Ponderosa pine Diseases and pests; Ponderosa pine Thinning. Discussion and This study indicates that, for at least a decade, moderately infested stands of Application sapling-sized ponderosa pine thinned to 250 trees per acre will produce as much wood as healthy stands thinned to the same density. This is not a new idea, because Shea (1964) and Belluschi (Shea and Belluschi 1965), working with indi- vidual tree growth rather than per acre wood production, found significant reductions in diameter growth only in "severely" infested trees. This study and other work (Barrett 1973) shows that height growth of individual trees, whether parasitized by dwarf mistletoe or not, may be increased by regulat- ing stand density and further augmented by controlling understory vegetation. General observation of the study area 11 years after the second thinning shows trees to be growing well over 10 inches in height per year in spite of heavily para- sitized lower branches (fig. 7). The appearance of abundant mistletoe in the lower crowns is disturbing to forest managers until they look closely at the growth in height and diameter that is taking place (figs. 8 and 9). One must conclude from the performance of these trees that good height and diameter growth can be maintained for several decades and that considerable dwarf mistletoe may be tol- erated in a managed Figure 7 —General view of a twice-thinned infested stand in 1983. 8. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Barrett, James W. (James Willis), 1922-; Roth, Lewis F. [Portland, Or. ] : U. S. Dept. of Agriculture, Forest Service, Pacific Northwest Forest and Range Experiment Station
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