Dichotomous table for gallers on Cannabis sativa
by Hans Roskam
1a On parts above ground => 2
1b Roots with small, nodular or spindle-shaped swellings. Meloidogyne hapla
1c Eelworm, making cysts on root surface. Heterodera humuli
2a Petioles and midribs, partially shortened, spongy, thickened; leaf blades stunted and distorted. Stem mainly at base, in case of later infestation also locally swollen and pale green higher up. Gall tissue brittle. Axial parts above bent or twisted galls ± severely stunted. In cases of early infestation additional side shoots develop. Ditylenchus dipsaci
2b Inflorescences, especially the female ones, disfigured and sometimes greened; development of fruits stunted. Phorodon cannabis