Dwarf mistletoe-pandora moth interaction and its contribution to ponderosa pine mortality in Arizona

The interaction between Southwestern dwarf mistletoe, Arceuthobtum vaginalum subspecies cryptopodum, infestation and defoliation by the pandora moth, Coloradia pandora pandora , on the Kaibab Plateau in Arizona was evaluated. Heavy defoliation of ponderosa pine, Pinus ponderosa, in 1979 and 1981 resulted in mortality of individual trees in areas of heavy dwarf mistletoe infestation. Postmortem evaluation of ponderosa pines indicated that dead trees had a significantly higher dwarf mistletoe rating than did nearby paired live trees. Of 25 tree pairs evaluated, only two live trees had higher dwarf mistletoe ratings than the paired dead tree. Mean dwarf mistletoe ratings were:live trees 2.9, dead trees 4.6 (6 class dwarf mistletoe rating system). Implications for management of the pandora moth are discussed

A Morphometric Analysis of Arceuthobium campylopodum and Arceuthobium divaricatum (Viscaceae)

Although the classification of pinyon dwarf mistletoe (Arceuthobium divaricatum, Viscaceae) has not been controversial to any extent since Engelmann described it in 1878, a recent taxonomic treatment has included this species in western dwarf mistletoe (A. campylopodum). While pinyon dwarf mistletoe is only known to parasitize pinyon pines (Pinus subsection Cembroides), western dwarf mistletoe as it has been known since the late 1800s is a principal parasite of Pinus ponderosa and P. jeffreyi and has never been observed parasitizing pinyon pines. With reservations about the recent classification of pinyon dwarf mistletoe and its treatment under A. campylopodum, we undertook this study to examine in detail the morphological characteristics of pinyon dwarf mistletoe and compare them with those of western dwarf mistletoe. Pinyon and western dwarf mistletoe populations were sampled throughout most of their geographic ranges and morphological traits including plant, flower, fruit, and seed dimensions were measured. Thereafter, we compared morphological characteristics between A. campylopodum and A. divaricatum using univariate and multivariate statistics to determine significant differences among morphologies of both male and female plants. Our analyses clearly demonstrated that pinyon and western dwarf mistletoe are morphologically distinct as originally proposed by G. Engelmann in the late 19th century. Furthermore, the host affinities of the two taxa clearly distinguish them from each other. Therefore, we recommend that A. campylopodum and A. divaricatum continue to be classified as separate species. Morphological differences between these species are summarized and a key is provided for use in their field identification

Comparison of Two Roadside Survey Procedures for Dwarf Mistletoes on the Sawtooth National Forest, Idaho

Two roadside surveys were conducted for dwarf mistletoes parasitizing lodgepole pine and Douglas-fir on the Sawtooth National Forest, Idaho. One survey used variable-radius plots located less than 150 m from roads. The 2nd survey used variable-radius plots established at 200-m intervals along 1600-m transects run perpendicular to the same roads. Estimates of the incidence (percentage of trees infected and percentage of plots infested) and severity (average dwarf mistletoe rating) for both lodgepole pine and Douglas-fir dwarf mistletoes were not significantly different for the 2 survey methods. These findings are further evidence that roadside-plot surveys and transect-plot surveys conducted away from roads provide similar estimates of the incidence of dwarf mistletoes for large forested areas

Comparison of Two Roadside Survey Procedures for Dwarf Mistletoes on the Sawtooth National Forest, Idaho

Two roadside surveys were conducted for dwarf mistletoes parasitizing lodgepole pine and Douglas-fir on the Sawtooth National Forest, Idaho. One survey used variable-radius plots located less than 150 m from roads. The 2nd survey used variable-radius plots established at 200-m intervals along 1600-m transects run perpendicular to the same roads. Estimates of the incidence (percentage of trees infected and percentage of plots infested) and severity (average dwarf mistletoe rating) for both lodgepole pine and Douglas-fir dwarf mistletoes were not significantly different for the 2 survey methods. These findings are further evidence that roadside-plot surveys and transect-plot surveys conducted away from roads provide similar estimates of the incidence of dwarf mistletoes for large forested areas

New combinations for Arceuthobium aureum (Viscaceae) in Mexico and Central America

Volume: 18Start Page: 501End Page: 50

TAXONOMIC STUDIES OF DWARF MISTLETOES (ARCEUTHOBIUM SPP.) PARASITIZING PINUS STROBIFORMIS

Volume: 42Start Page: 120End Page: 12

ADDITIONAL TAXONOMIC STUDIES OF ARCEUTHOBIUM PENDENS (VISCACEAE): A RARE DWARF MISTLETOE FROM CENTRAL MEXICO

Volume: 53Start Page: 69End Page: 7