Vertical Distribution of Hop Cyst Nematode in Hop Gardens in Central Europe

摘要

The genus Heterodera consists of 80 valid species which are distributed all over the world and they range from mono to polyphagous (Subotin et al., 2010). Several species are considered economically important (or quarantine), including H. humuli Filipjev, 1934. Previous studies on H. humuli or H. humuli as a vector of plant viruses were focused on its geographical distribution, biology, life cycle, and pathogenicity symptoms (Barbez, 1982; Lopez-Robles, 1995; Valdez et al., 1974). There were no reports of the vertical distribution of this species within the soil pro?le which is dependent on the large root system of hop plants. Mature hop plants have two types of roots: lateral spreading roots, 2-5 m long, that are wiry and extensively branched resulting in a ?brous layer in the top 20-30 cm of the soil, and vertical roots, 2-9 m long, that are ?eshy, irregularly swollen, brittle and rarely branched. High population densities of H. humuli were found only in young, ?brous roots of hop plants (Mikhailyukov and Sigareva, 1981).