First Report of Arceuthobium hondurense in Oaxaca, Mexico

Honduran dwarf mistletoe (Arceuthobium hondurense Hawksw. & Wiens) has only been found in four locations in Honduras: west of Zamorano, east of Lepaterique, Cusuco National Park, and Celaque National Park (1,2). At one time it was believed that this mistletoe could be in danger of extinction (1). However, it has also been reported in two locations in Chiapas, Mexico (3). In December 2000, ≈1 km north of Suchixtepec, Oaxaca, Mexico, near Route 175 (elevation 2,770 m), we collected a dwarf mistletoe parasitizing Pinus tecunumanii (Schw.) Eguiluz et Perry that was morphologically similar to A. hondurense (1). This population initially had been classified as A. nigrum Hawksw. & Wiens (1), but is now classified as A. hondurense based on morphology (male flower color and stigma length) (1) and analysis of nuclear rDNA internal transcribed spacer (ITS) sequences from Honduras (GenBank Accession No. AF325969) and Oaxaca (GenBank Accession No. AY055215). A comparison of these two A. hondurense ITS sequences indicated they are very closely related to each other, whereas both are distinct from A. nigrum (GenBank Accession No. L25693). Specimens of A. hondurense from Oaxaca were deposited at the Deaver Herbarium, Northern Arizona University, Flagstaff. To our knowledge, this is the first report of A. hondurense in Oaxaca, Mexico, and extends its known distribution west across the Isthmus of Tehuantepec from central Chiapas by ≈400 km. References: (1) F. G. Hawksworth and D. Wiens. Dwarf Mistletoes: Biology, Pathology, and Systematics. USDA Agric. Handb. 709, 1996. (2) R. Mathiasen et al. Phytologia 85:268, 1998. (3) R. Mathiasen et al. Plant Dis. 85:444, 2001.

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First Report of Arceuthobium hondurense on Pinus tecunumannii

Plant Disease ◽

10.1094/pdis.2000.84.3.372c ◽

2000 ◽

Vol 84 (3) ◽

pp. 372-372

Author(s):

R. Mathiasen ◽

J. Beatty ◽

J. Melgar

Keyword(s):

National Park ◽

East Side ◽

Dwarf Mistletoe ◽

First Report ◽

Northern Arizona ◽

Shoot Production ◽

Northern Arizona University ◽

Pinus Oocarpa ◽

Celaque National Park

Honduran dwarf mistletoe (Arceuthobium hondurense Hawksw. & Wiens) is a rare dwarf mistletoe found only in Honduras (1,2). Thus far, it has been reported to parasitize only Pinus oocarpa Schiede (2). In October 1999, we observed infection by A. hondurense on P. tecunumannii (Schw.) Eguiluz et Perry along the trail to the summit of Montana del Celaque (elevation 1,750 to 1,800 m) on the east side of Celaque National Park, ≈5 km west of Gracias (Department Lempira), Honduras. Infected pines had witches′ brooms, and mistletoe shoot production was common on infected branches. This is the first report of A. hondurense on P. tecunumannii. Specimens of A. hondurense from P. tecunumannii were collected and have been deposited at the Herbario, Escuela Nacional de Ciencias Forestales, Siguatepeque, Honduras, and at the Deaver Herbarium, Northern Arizona University, Flagstaff. References: (1) F. G. Hawksworth and D. Wiens. 1996. Dwarf Mistletoes: Biology, Pathology, and Systematics. U.S. Dep. Agric. Agric. Handb. 709. (2) R. Mathiasen et al. Phytologia 36:211, 1998.

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First Report of Psittacanthus angustifolius on Pinus oocarpa and Pinus maximinoi

Plant Disease ◽

10.1094/pdis.2000.84.2.203a ◽

2000 ◽

Vol 84 (2) ◽

pp. 203-203 ◽

Cited By ~ 1

Author(s):

R. Mathiasen ◽

J. Melgar ◽

J. Beatty ◽

C. Parks

Keyword(s):

National Park ◽

Parasitic Plant ◽

First Report ◽

Northern Arizona ◽

Single Tree ◽

Northern Arizona University ◽

Pinus Oocarpa ◽

Host Mortality ◽

Celaque National Park ◽

Main Entrance

The mistletoe Psittacanthus angustifolius Kuijt (Loranthaceae) was first described in 1987 on Pinus from Nicaragua near the Honduran border, but the species of pine was not designated (1). Kuijt (1) speculated that this mistletoe probably also occurs in Honduras. During March and October 1999 we observed P. angustifolius parasitizing Pinus oocarpa Schiede in the departments of Choluteca, Francisco Morazan, El Paraiso, Intibuca, Lempira, and Olancho in Honduras. This mistletoe appears to be a very common parasitic plant on pines in Honduras and is associated with host mortality. We also observed P. angustifolius parasitizing Pinus maximinoi H.E. Moore at two locations in the department of Lempira: one infection on a single tree 1.5 km east of El Matazano (elevation 1,400 m) and six and eight infections on two trees 0.5 km west of the main entrance to Celaque National Park east of Gracias (elevation 1,200 m). This is the first report of P. angustifolius in Honduras and the first report of this mistletoe on Pinus oocarpa and Pinus maximinoi. Specimens of P. angustifolius from Pinus oocarpa and Pinus maximinoi have been deposited at the Herbario, Escuela Nacional de Ciencias Forestales, Siguatepeque, Honduras, and at the Deaver Herbarium, Northern Arizona University, Flagstaff. Reference: (1) J. Kuijt. Ann. Mo. Bot. Gard. 74:511, 1987.

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First Report of Arceuthobium vaginatum subsp. cryptopodum on Pinus mugo

Plant Disease ◽

10.1094/pdis.2003.87.11.1395c ◽

2003 ◽

Vol 87 (11) ◽

pp. 1395-1395

Author(s):

R. Mathiasen ◽

M. Haefeli ◽

D. Leatherman

Keyword(s):

Pinus Ponderosa ◽

Ponderosa Pine ◽

Pinus Mugo ◽

Black Forest ◽

Dwarf Mistletoe ◽

First Report ◽

Northern Mexico ◽

Northern Arizona ◽

Positive Identification ◽

Northern Arizona University

Southwestern dwarf mistletoe (Arceuthobium vaginatum (Willd.) Presl subsp. cryptopodum (Engelm.) Hawksw. & Wiens, family Viscaceae) is a serious and common pathogen of ponderosa pine (Pinus ponderosa Douglas ex Lawson & C. Lawson) in Colorado, Utah, Arizona, New Mexico, and northern Mexico (1). In July 2002, this dwarf mistletoe was observed parasitizing a 1.4-m tall mugo pine (P. mugo Turra) in the Black Forest north of Colorado Springs, CO (39°02.118′N, 104°36.028′W, elevation 2,250 m). The infected mugo pine was planted as an ornamental approximately 6 m from a ponderosa pine infected with A vaginatum subsp. cryptopodum. Dwarf mistletoe shoots were produced on the only infected branch observed but this was sufficient for a positive identification of the dwarf mistletoe. Although J. Weir successfully inoculated mugo pine with western dwarf mistletoe (A. campylopodum Engelm.) and lodgepole pine dwarf mistletoe (A. americanum Nutt. ex Engelm.) (2), to our knowledge, this is the first report of a dwarf mistletoe occurring naturally on P. mugo, as well as the first report of A vaginatum subsp. cryptopodum on P. mugo (1). Specimens of A vaginatum subsp. cryptopodum from P. mugo have been deposited in the Deaver Herbarium, Northern Arizona University, Flagstaff (Accession No. 73761). References: (1) F. Hawksworth and D. Wiens. Dwarf mistletoes: biology, pathology, and systematics. USDA Agric. Handb. 709, 1996. (2) J. Weir. Bot. Gaz. 56:1, 1918.

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First Report of White Fir Dwarf Mistletoe on Mountain Hemlock

Plant Disease ◽

10.1094/pdis.2002.86.11.1274c ◽

2002 ◽

Vol 86 (11) ◽

pp. 1274-1274

Author(s):

R. Mathiasen

Keyword(s):

United States ◽

Western United States ◽

Abies Concolor ◽

Dwarf Mistletoe ◽

First Report ◽

Northern Arizona ◽

White Fir ◽

Wilderness Area ◽

Northern Arizona University ◽

Tsuga Mertensiana

White fir dwarf mistletoe (Arceuthobium abietinum Engelm. ex Munz f. sp. concoloris Hawksw. & Wiens) is a serious and common pathogen of white fir (Abies concolor (Gord. & Glend.) Hildebr.), grand fir (A. grandis (Dougl. ex D. Don) Lindl.), and Low's fir (A. lowiana (Gord.) A. Murr.) in the western United States (1). In August 2002, this dwarf mistletoe was observed parasitizing mountain hemlock (Tsuga mertensiana (Bong.) Carr.) growing among severely infected grand fir near the trailhead to Cabot Lake in the Mount Jefferson Wilderness Area, Oregon at 44°34′27″N, 121°43′43″W, elevation 1,340 m. Only 2 of 27 mountain hemlocks observed in this area were infected. One tree had four infections, and one tree had two infections. Several fully developed male plants were found on one of the infected branches of mountain hemlock and were morphologically similar to those growing on the nearby grand fir. Other dwarf mistletoes that commonly parasitize mountain hemlock (Arceuthobium tsugense subsp. mertensianae and Arceuthobium laricis) were not observed in the area. In addition, white fir dwarf mistletoe can be distinguished from these mistletoes by its larger, yellowish shoots (1). Specimens of the mistletoe from mountain hemlock have been deposited in the Deaver Herbarium, Northern Arizona University, Flagstaff. To my knowledge, this is the first report of white fir dwarf mistletoe on mountain hemlock (1). Reference: (1) F. Hawksworth, and D. Wiens. Dwarf mistletoes: biology, pathology, and systematics. USDA Agric. Handb. 709, 1996

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First Report of Arceuthobium hondurense in Mexico

Plant Disease ◽

10.1094/pdis.2001.85.4.444a ◽

2001 ◽

Vol 85 (4) ◽

pp. 444-444 ◽

Cited By ~ 2

Author(s):

R. Mathiasen ◽

D. Nickrent ◽

C. Parks ◽

J. Beatty ◽

S. Sesnie

Keyword(s):

Pine Forests ◽

Nuclear Rdna ◽

Dwarf Mistletoe ◽

First Report ◽

Northern Arizona ◽

Rdna Its ◽

Las Casas ◽

Northern Arizona University ◽

Pinus Tecunumanii ◽

Rdna Its Sequences

Honduran dwarf mistletoe (Arceuthobium hondurense Hawksw. & Wiens) is a rare dwarf mistletoe previously known only from Honduras (1,2). In March 2000 we collected a dwarf mistletoe from approximately 7 km west of San Cristobal de las Casas, Chiapas, Mexico near Route 190 (elevation 2,440 m), which was morphologically similar to A. hondurense (1). This population had initially been classified as A. nigrumHawksw. & Wiens (1). However, our morphological measurements and analysis of nuclear rDNA ITS sequences of A. hondurense plants from Honduras (GenBank No. AF325969) and the plants from Chiapas (AF325970) have confirmed that the Chiapan population is A. hondurense and not A. nigrum. An additional population of A. hondurense was discovered in Chiapas approximately 11 km west of Oxchuc near Route 186 (elevation 2160 m). Both of the Chiapan populations of A. hondurense were parasitizing Pinus tecunumanii(Schw.) Eguiluz et Perry. Specimens of A. hondurense from Chiapas were deposited at the Deaver Herbarium, Northern Arizona University, Flagstaff. This is the first report of A. hondurense in Mexico and extends its known distribution from northwestern Honduras (3) by approximately 500 km. Although A. hondurense has not been observed in the pine forests of Guatemala, it is probable that it also occurs there (1). References: (1) F. G. Hawksworth and D. Wiens. 1996. Dwarf Mistletoes: Biology, Pathology, and Systematics. USDA Agric. Handb. 709. (2) R. Mathiasen et al. Phytologia 36:211, 1998. (3) R. Mathiasen et al. Plant Dis. 84:372, 2000.

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First Report of Arceuthobium hawksworthii in Honduras

Plant Disease ◽

10.1094/pdis.2002.86.7.815a ◽

2002 ◽

Vol 86 (7) ◽

pp. 815-815 ◽

Cited By ~ 1

Author(s):

R. Mathiasen ◽

B. Howell ◽

J. Melgar

Keyword(s):

Pinus Caribaea ◽

Dwarf Mistletoe ◽

First Report ◽

Pine Ridge ◽

Northern Arizona ◽

Mountain Pine ◽

Northern Arizona University ◽

Ridge Area ◽

Caribbean Pine ◽

Pinus Caribaea Morelet

The dwarf mistletoe Arceuthobium hawksworthii D. Wiens & C. G. Shaw (Viscaceae) has only been reported from the Mountain Pine Ridge area of Belize (1). We observed this dwarf mistletoe parasitizing its principal host, Caribbean pine (Pinus caribaea Morelet var. hondurensis (Senecl.) Barrett & Golf.) (1), 10 km east of Gualaco, Department Olancho, Honduras (elevation 800 m). Several trees were severely infected, and some dwarf mistletoe-associated mortality was observed at this location. The identification of A. hawksworthii was confirmed by comparing specimens collected from Honduras with specimens from Belize, which are deposited at the Deaver Herbarium, Northern Arizona University, Flagstaff. The mistletoes Psittacanthus angustifolius Kuijt and P. pinicola Kuijt (Loranthaceae) were also observed at this location parasitizing Caribbean pine. However, infection by both of these mistletoes was not severe, and no mistletoe-associated mortality was observed. Specimens of these mistletoes from Caribbean pine have been deposited at the Herbario, Escuela Nacional de Ciencias Forestales, Siguatepeque, Honduras. To our knowledge, this is the first report of A. hawksworthii from Honduras and extends its range approximately 350 km to the east-southeast of the Mountain Pine Ridge in Belize. This is also the first report P. angustifolius on Caribbean pine, but P. pinicola commonly infects this host in northern Honduras and Belize (2). References: (1) F. G. Hawksworth and D. Wiens. Dwarf mistletoes: biology, pathology, and systematics. Agric. Handb. 709, 1996. (2) J. Kuijt. Ann. Mo. Bot. Gard. 74:511, 1987.

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First Report of Arceuthobium aureum subsp. aureum in Mexico

Plant Disease ◽

10.1094/pdis-91-4-0469b ◽

2007 ◽

Vol 91 (4) ◽

pp. 469-469

Author(s):

R. Mathiasen ◽

B. Howell ◽

G. Garnett

Keyword(s):

Type Locality ◽

Flowering Period ◽

Dwarf Mistletoe ◽

First Report ◽

Northern Arizona ◽

Northern Arizona University ◽

Pinus Spp

The golden dwarf mistletoe (Arceuthobium aureum Hawksw. & Wiens subsp. aureum, Viscaceae) parasitizes several pines (Pinus spp., Pinaceae) in central Guatemala (1). In September 2006, we observed golden dwarf mistletoe parasitizing Pinus maximinoi H.E. Moore in southern Chiapas, Mexico; 1 km west of El Rosario along Mexico Route 211 (15°19′23″N, 92°17′45″W, elevation 1,720m). Golden dwarf mistletoe can be distinguished from the closely related Peterson's dwarf mistletoe (A. aureum Hawksw. & Wiens subsp. petersonii Hawksw. & Wiens) by its smaller shoots, occurrence below 2,200 m in elevation, and flowering period (1). The shoots of the dwarf mistletoe at the El Rosario location were less than 20 cm high and male plants were not flowering. Male plants of Peterson's dwarf mistletoe observed at the type locality and other locations in Chiapas during September were in full flower. Although only 29 trees were infected at this location, infection was severe on 11 trees, but no mortality associated with dwarf mistletoe infection was observed. Mistletoe infection did not induce the formation of witches'-brooms near El Rosario, but infection by golden dwarf mistletoe on P. maximinoi does induce witches'-brooms on older trees in Guatemala (2). The golden dwarf mistletoe population near El Rosario is approximately 150 km west of the nearest known population of this species in Guatemala (1). To our knowledge, this is the first report of golden dwarf mistletoe in Mexico. Specimens of golden dwarf mistletoe from Chiapas, Mexico were deposited at the Deaver Herbarium, Northern Arizona University, Flagstaff (Accession No. 83122). References: (1) F. Hawksworth and D. Wiens. Dwarf Mistletoes: Biology, Systematics, and Pathology. USDA For. Serv. Agric. Handb. 709, 1996. 2) R. Mathiasen et al. Madrono 23:122, 2004.

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First Report of Durangan Dwarf Mistletoe, Arceuthobium vaginatum subsp. durangense, on Pinus cooperi and P. engelmannii in Mexico

Plant Disease ◽

10.1094/pdis-91-9-1201a ◽

2007 ◽

Vol 91 (9) ◽

pp. 1201-1201 ◽

Cited By ~ 1

Author(s):

R. Mathiasen

Keyword(s):

Molecular Evidence ◽

Dwarf Mistletoe ◽

Sierra Madre Occidental ◽

First Report ◽

The Road ◽

Northern Arizona ◽

Bright Orange ◽

Northern Arizona University ◽

Sierra Madre ◽

Pinus Spp

The Durangan dwarf mistletoe (Arceuthobium vaginatum subsp. durangense Hawksw. & Wiens, Viscaceae) parasitizes several species of pines (Pinus spp., Pinaceae) in the Mexican states of Durango, Sinaloa, and Jalisco (1,3). This mistletoe has primarily been reported from the western edge of the Sierra Madre Occidental in eastern Sinaloa and western Durango, but its distribution there is not well documented (3). In March 2007, I found Durangan dwarf mistletoe parasitizing Pinus engelmannii Carr., approximately 25 km north of Mexico Route 40 (24°00′51″N, 105°26′48″W, elevation 2,200 m), and on P. cooperi Blanco approximately 90 km north of Route 40 (24°24′40″N, 105°35′26″W, elevation 2,710 m) along the road to San Miguel de las Cruces, Durango. These populations are approximately 50 and 80 km northeast of the closest known population of Durangan dwarf mistletoe west of Buenos Aires along Route 40 in extreme western Durango. Infection of P. engelmannii was severe on 25 trees, but only severe on two trees of P. cooperi. No mortality associated with infection by Durangan dwarf mistletoe was observed at either location. Infection caused large, nonsystemic witches' brooms on P. engelmannii, but no brooms were observed on infected P. cooperi. To my knowledge, this is the first report of Durangan dwarf mistletoe on P. cooperi and P. engelmannii, and the first report of this mistletoe from the central Sierra Madre Occidental (3). Although Hawksworth and Wiens (2,3) treated Durangan dwarf mistletoe as a species (A. durangense Hawksw. & Wiens), I use the earlier classification of Durangan dwarf mistletoe as a subspecies of Mexican dwarf mistletoe (A. vaginatum (Willd.) Presl subsp. vaginatum) (1) because of recent molecular evidence (4) and morphological similarities with Mexican dwarf mistletoe. The principal difference between these mistletoes is that plants of Durangan dwarf mistletoe are bright orange while those of Mexican dwarf mistletoe are dark brown to black (1–3). Specimens of Durangan dwarf mistletoe on Pinus engelmannii and P. cooperi have been deposited at the Deaver Herbarium, Northern Arizona University, Flagstaff (Accession Nos. 76455 and 76456, respectively). References: (1) F. G. Hawksworth and D. Wiens, Brittonia 17:213, 1965. (2) F. G. Hawksworth and D. Wiens. Phytologia 66:3, 1989. (3) F. G. Hawksworth and D. Wiens. USDA For. Serv. Agric. Handb. 709, 1996. (4) D. L. Nickrent et al. Am. J. Bot. 91:125, 2004.

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First Report of Mountain Hemlock Dwarf Mistletoe (Arceuthobium tsugense subsp. mertensianae) on Sugar Pine (Pinus lambertiana) from Oregon

Plant Disease ◽

10.1094/pdis-93-3-0321a ◽

2009 ◽

Vol 93 (3) ◽

pp. 321-321

Author(s):

R. Mathiasen ◽

C. Daugherty

Keyword(s):

Sierra Nevada ◽

Plant Size ◽

The Other ◽

White Pine ◽

Dwarf Mistletoe ◽

First Report ◽

Northern Arizona ◽

Sierra Nevada Mountains ◽

Sugar Pine ◽

Northern Arizona University

Mountain hemlock dwarf mistletoe (Arceuthobium tsugense (Rosendahl) G.N. Jones subsp. mertensianae Hawksw. & Nickrent, Viscaceae) commonly parasitizes mountain hemlock (Tsuga mertensiana (Bong.) Carr.) from the central Sierra Nevada Mountains to the southern Cascades in Oregon (1,3). It has also been reported to commonly parasitize whitebark pine (Pinus albicaulis Engelm.) and occasionally western white pine (P. monticola Dougl. ex D. Don) (1,4). In September of 2008, we found mountain hemlock dwarf mistletoe infecting two sugar pines (P. lambertiana Dougl.) 4.5 km north of Windigo Pass, Oregon (42°24′40″N, 123°35′26″W, elevation 2,710 m). One of the sugar pines was 63.5 cm (25 inches) in diameter and had three infections. The other tree was 22.4 cm (9 inches) in diameter, but had 17 infections, many with mistletoe plants that allowed identification of the mistletoe using published descriptions (1,2). Mountain hemlock dwarf mistletoe can be distinguished from sugar pine dwarf mistletoe (A. californicum Hawksw. & Wiens) by its smaller plant size (mean height 5 cm versus 8 cm) and plant color (green-brown versus green to yellow) (1,2). An area (site) of approximately 1 ha around the infected sugar pines was examined and none of the other sugar pines we observed (33 trees) were found to be infected. Because mountain hemlock dwarf mistletoe also occurs in the principal range of sugar pine in the Sierra Nevada Mountains, it may also parasitize this tree there. However, our observations in several mountain hemlock stands infested with mountain hemlock dwarf mistletoe in California have failed to uncover infection of sugar pine by this mistletoe. Therefore, we would tentatively classify sugar pine as a rare host of mountain hemlock dwarf mistletoe (1). Specimens of mountain hemlock dwarf mistletoe on sugar pine were collected and deposited at the Deaver Herbarium (ASC), Northern Arizona University, Flagstaff (Accession No. 87122). To our knowledge, this is the first report of mountain hemlock dwarf mistletoe parasitizing sugar pine. References: (1) F. G. Hawksworth and D. Wiens. USDA For. Serv. Agric. Handb. 709, 1996. (2) F. G. Hawksworth et al. Novon 2:204, 1992. (3) R. L. Mathiasen and C. M. Daugherty. Novon 17:222, 2007. (4) R. L. Mathiasen and F. G. Hawksworth. For. Sci. 34:429, 1988.

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First Report of Limber Pine Dwarf Mistletoe (Arceuthobium cyanocarpum) on Sugar Pine (Pinus lambertiana) from California

Plant Disease ◽

10.1094/pdis-94-1-0134c ◽

2010 ◽

Vol 94 (1) ◽

pp. 134-134

Author(s):

R. Mathiasen ◽

C. Daugherty

Keyword(s):

White Pine ◽

Dwarf Mistletoe ◽

Male And Female ◽

Pinus Flexilis ◽

First Report ◽

Northern Arizona ◽

Limber Pine ◽

Sugar Pine ◽

Northern Arizona University ◽

Western White Pine

Limber pine dwarf mistletoe (Arceuthobium cyanocarpum (A. Nelson ex Rydberg) Coulter & Nelson; Viscaceae) severely parasitizes limber pine (Pinus flexilis James) and several other white pines, including western white pine (P. monticola Dougl. ex D. Don) and whitebark pine (P. albicaulis Engelm.), over an extensive geographic range in the western United States (1). However, limber pine dwarf mistletoe has not been previously reported on sugar pine (P. lambertiana Dougl.), another white pine found within the range of limber pine dwarf mistletoe (1). In August 2009, we found a sugar pine infected with limber pine dwarf mistletoe approximately 0.8 km northeast of Tahquitz Peak in the San Jacinto Mountains, California (33°45′24′′N, 116°40′24′′W; elevation 2,640 m). The infected sugar pine was 13 inches (33 cm) in diameter and had 13 infections on five of its lower branches. Ten of the infections were producing mature male and female mistletoe plants with open flowers or developing fruits, respectively. Two of the infected branches were forming witches' brooms in response to infection by limber pine dwarf mistletoe. The infected sugar pine was growing within 3 m of four limber pines severely infected with limber pine dwarf mistletoe. The male and female plants produced on the infected sugar pine were morphologically identical to those growing on the infected limber pines. Limber pine dwarf mistletoe can be distinguished from sugar pine dwarf mistletoe (A. californicum Hawksw. & Wiens), the principal dwarf mistletoe parasitizing sugar pine in California, by its smaller plants (mean height 3 cm versus 8 cm) and flowering period (August to September versus June to July). In an attempt to determine the relative susceptibility of sugar pine to limber pine dwarf mistletoe, we conducted a survey of the infested limber pine stand. Because there were no additional sugar pines growing in the area, it was impossible to assess the general susceptibility of sugar pine to limber pine dwarf mistletoe, but the production of many mature plants from 10 of the infections on the sugar pine suggests this tree species may be highly susceptible. However, this is currently the only known location where sugar pine co-occurs with limber pine dwarf mistletoe (1), so assessing the susceptibility of sugar pine to this dwarf mistletoe will depend on locating additional sites where they co-occur. It should be noted also that previous surveys in the San Jacinto Mountains failed to detect infection by limber pine dwarf mistletoe on sugar pine (1). Specimens of limber pine dwarf mistletoe on sugar pine were collected and deposited at the Deaver Herbarium (ASC), Northern Arizona University, Flagstaff (Accession No. 92697). To our knowledge, this is the first report of limber pine dwarf mistletoe parasitizing sugar pine. References: (1) F. G. Hawksworth and D. Wiens. USDA For. Serv. Agric. Handb. 709, 1996.

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