U.S. Department of Agriculture, ARS, Southeastern Fruit and Tree Nut Research Laboratory, Byron, GA 31008
Istitutto di Nematologia Agraria, CNR, Bari, Italy
In April 2000, a Xiphinema sp. was found in a peach (Prunus persica (L.) Batsch) orchard during a longidorid nematode survey in Concord, GA. The nematode was recovered from the rhizosphere of healthy and dying peach trees established on Lovell rootstock. Following a comparative microscope study, the species was identified as X. pacificum Ebsary, Vrain, & Graham, a putative species of the X. americanum group (2). All morphometric measurements coincided with the original description (1). In North America, this group of nematodes are natural vectors of four economically important nepoviruses that are responsible for causing substantial damage to a wide variety of crops. In spring 1999, tree death from bacterial canker (Pseudomonas syringae pv. syringae) occurred within this then 2-year-old orchard. Samples showed that populations of X. pacificum and Pratylenchus sp. were greater under dying trees (34 and 143/100 cm3 of soil) than under healthy trees (19 and 30/100 cm3 of soil), respectively. Samples taken during the 2000 survey contained 10 X. pacificum per 100 cm3 soil under apparently healthy trees. This nematode was originally described from British Columbia, Canada, where it seemed to be restricted in its distribution to vineyards in the south Okanagan Valley. To our knowledge, this is the first report of X. pacificum in the United States.
References: (1) B. A. Ebsary et al. Can. J. Zool. 67:801, 1989. (2) F. Lamberti et al. Russian J. Nematol. 8:65, 2000.