Heterodera humuli Filipjev, 1934

Bernard, Ernest C, Chaffin, Angel G & Gwinn, Kimberly D, 2022, Review of nematode interactions with hemp (Cannabis sativa), Journal of Nematology 54 (1), pp. 1-18 : 5

Heterodera humuli Filipjev (hop cyst nematode)

Summaries and illustrations of H. humuli include those of Stone and Rowe (1977) and Spaar et al. (1990). This nematode, described in 1934, had previously been considered H. schachtii “hops strain” ( Filipjev and Schuurmans Stekhoven, 1941). Hollrung (1890) reported H. schachtii on hemp as well as many other plants and later found H. schachtii juveniles on hemp roots ( Hollrung, 1891). These records certainly indicate a wide range of other later-described cyst nematode species. Goodey et al. (1965), in their list of hosts of plant-parasitic nematodes, suggested that Hollrung’s record might have been H. humuli . Franklin (1951) indicated that H. humuli reproduced successfully on hemp, but did not provide additional information. In a laboratory study H. humuli successfully matured on hemp ( Winslow, 1954). Jensen et al. (1962) considered hemp to be a host of H. humuli on the basis of previous European records, although not from experimental results. Conversely, hemp-root diffusates did not stimulate H. humuli egg hatch ( De Grisse and Gillard, 1963), and isolates of this nematode from hop and nettle did not develop on C. sativa ( Subbotin, 1986) . None of these reports specified the hemp type or cultivar. As the identifications of the H. humuli populations in these latter experiments were made by experienced nematologists it seems likely that its ability to parasitize hemp is variable; the nematode may have host-selected populations or hemp varieties may differ in reaction as they do with root-knot nematodes.