03045nas a2200157   4500008004100000022001400041245009400055210006900149260001200218300001400230490000700244520256000251100001402811700001702825856004502842       2005                        eng d  a0191-291700aCrown rot of Abies balsamea var. phanerolepis caused by Phytophthora cactorum in Virginia0 aCrown rot of Abies balsamea var phanerolepis caused by Phytophth  c04/2005  a433 - 4330 v893 a<p>In early July 2004, a severe crown rot of Canaan fir (<em>Abies balsamea</em> var. <em>phanerolepis</em> Fern.) was reported to the Virginia Cooperative Extension, Frederick County Office, and subsequently to the Virginia Tech Disease Clinic in Virginia Beach. One thousand five-year-old Canaan fir transplants (approximately 11 mm in caliper and 31 cm high) had been purchased from a tree nursery in Oregon and planted in the field in Frederick County, VA, in April of 2004. The field site had not been cultivated for 4 years after an apple orchard had been removed in 2000. By mid-May, needle browning had become serious, affecting the lower crown first. By August, transplants had suffered 40% mortality. Basal stems of affected plants were obviously discolored. Root and basal stem samples from several infected plants were then cultured on PARP-V8 agar on three different dates. <em>Phytophthora</em> sp. isolates were recovered from all stem samples but none from the roots. These isolates produced a large number of papillate sporangia that were caducous with short pedicels. Abundant oogonia with paragynous antheridia formed oospores directly on isolation plates within 7 days. The isolates were keyed as <em>P. cactorum</em> (2). This identification was confirmed using a single-strand-conformation polymorphism analysis of ribosomal DNA internal transcribed spacer (ITS)-1 (4). It appears that the source of inoculum was <em>P. cactorum</em> associated with the previous apple crop, since Canaan fir from the same transplant lot planted in a nearby field without a history of apples remained healthy. <em>P. cactorum</em> has been reported to cause root rot of noble fir (<em>A. procera</em> Rhedo), Pacific silver fir (<em>A. amabilis</em> (Dougl.) Forbes), and Shasta red fir (<em>A. magnifica</em> var. <em>shastensis</em> Lemm.) in the Pacific Northwest (3). It has also caused crown rot of Fraser fir (<em>A. fraseri</em> (Pursh) Poir.), noble fir, white fir (<em>A. concolor</em> (Gord. &amp; Glend.) Lindl.), and balsam fir (<em>A. balsamea</em> (L.) Mill.) in Michigan (1). To our knowledge, this is the first report of <em>P. cactorum</em> attacking Canaan fir. Canaan fir currently is a recommended Christmas tree species for areas where Fraser fir does not do well due to root rot caused by <em>Phytophthora cinnamomi</em>. This study suggests that such a recommendation must be used with caution. Growing Canaan fir trees in <em>P. cactorum</em>-infested soil could result in devastating crop losses as reported in this note.</p>1 aHong, C X1 aMarston, C D  u  http://dx.doi.org/10.1094/PD-89-0433B 