First Report of Cactodera milleri in Wisconsin

During the summer of 2005, lemon-shaped cysts and second-stage juveniles of a cyst nematode were recovered from soil at the University of Wisconsin Agricultural Research Station in Hancock, WI. Samples were collected on multiple dates from a plot (61 × 12 m) in continuous potato production for 20 years with significant weed pressure. PCR-restriction fragment length polymorphism profiles of the internal transcribed spacer (ITS) 1 region using restriction enzyme HhaI indicated Cactodera spp. (2). Morphological observations and morphometrics made on cysts, males, J2s, and eggs were consistent with Cactodera milleri Graney and Bird, 1990 (1). Host range studies were conducted in a growth chamber. Soybean, potato, and beet did not support nematode development and reproduction. Common lambsquarters (Chenopodium album), a known host of C. milleri, was an excellent host. No obvious aboveground disease symptoms were evident on lambsquarters in the growth chamber assay. This detection represents the first record of C. milleri in Wisconsin. Unless detailed morphological or molecular measurements are made, C. milleri may be easily confused with the soybean cyst nematode, Heterodera glycines. The presence of lambsquarters in fields planted with glyphosate-resistant soybeans makes the recovery of both nematode species in a single soil sample possible. References: (1) L. S. O. Graney and G. W. Bird. J. Nematol. 22:457, 1990. (2) A. L. Szalanski et al. J. Nematol. 29:255, 1997.