Subanguina radicicola, the Root-Gall Nematode Infecting Poa annua in New Brunswick, Canada

Poa annua frequently is found as the dominant turfgrass species on golf course putting greens grown in the range of cool-season grasses. While not intentionally established, it is an aggressive weed in stands of bentgrasses (Agrostis spp.). When significant encroachment of P. annua occurs, it often is maintained indefinitely. In May 2003, P. annua putting greens at the Riverside Country Club in Rothesay, New Brunswick, Canada showed signs of an unidentified disease. Putting greens were slow to green up and large chlorotic patches were evident across affected areas. When roots were examined, extensive galling was observed. Galls were slender and often twisted in appearance. Upon dissection of washed galls, hundreds of eggs were exuded into the surrounding water droplet, and mature male and female nematodes were observed. Further morphological examination of males, females, and juvenile nematodes demonstrated that they were Subanguina radicicola (Greef 1872) Paramanov 1967 (1,2). Each P. annua plant had an average of four galls (with a range of two to nine) primarily located within the uppermost centimeter of the soil. Of 18 P. annua putting greens, four were affected by the nematode and displayed the same damage symptoms. S. radicicola has been identified from American beachgrass in Rhode Island and from P. annua in Oregon, but to our knowledge, this is the first report of the nematode affecting P. annua on a golf course in eastern North America. References: (1) W. F. Mai and P. Mullin. Plant-Parasitic Nematodes: A Pictorial Key to Genera. Cornell University Press, Ithaca, New York, 1996. (2) G. Thorne. Principles of Nematology. McGraw-Hill Book Company, Inc., New York, 1961.