First Report of Subanguina radicicola, the Root-Gall Nematode Infecting Poa annua Putting Greens in Washington State

In the fall of 2006, a golf course in Snoqualmie, WA renovated five putting greens with commercially produced Poa annua L. sod from British Columbia, Canada. Prior to the renovation, the greens had been planted with Agrostis stolonifera L. cv. Providence, which was removed during the renovation. In February of 2007, chlorotic patches were observed on the newly established P. annua greens. When the roots were examined, extensive galling was observed throughout plant roots. Galls were slender and twisted in appearance and less than one millimeter long. Upon dissection of washed galls, hundreds of eggs were exuded into the surrounding water droplet and both mature male and female nematodes were observed. Further morphometric examination of males, females, and juvenile nematodes demonstrated that they were Subanguina radicicola (Greef 1872) Paramanov 1967 (1). Amplification of nematode 18S, ITS1, and 5.8S regions, using previously published primers (2), resulted in a 100% sequence match with the publicly available sequence for S. radicicola, GenBank Accession No. AF396366. Each P. annua plant had an average of six galls (with a range of 1 to 8), primarily located within the top 2 cm of the soil. All five new P. annua putting greens at the golf course were infested with the nematode. Additionally, P. annua from two A. stolonifera cv. Providence greens that had not been renovated was infected, suggesting that the population occurred onsite and was not imported from the Canadian sod. S. radicicola has been identified as causing severe damage in New Brunswick, Canada on P. annua putting greens and in wild P. annua in the northwestern United States, but to our knowledge, this is the first report of the nematode affecting P. annua on a golf course in the United States. References: (1) E. L. Krall. Wheat and grass nematodes: Anguina, Subanguina, and related genera. Pages 721-760 in: Manual of Agricultural Nematology. Marcel Dekker, New York, 1991. (2) N. A. Mitkowski et al. Plant Dis. 86:840, 2002.