Dichotomous table for gallers on Helianthus
by Hans Roskam
1a On above-ground parts => 2
1b Roots with almost rotund swellings, up to 4 mm long, sometimes clustered. H. annuus: Meloidogyne hapla
= Heterodera schachtii is known from H. annuus
2a Galls on root collar or on stem. The inducers are inside the galls => 4
2b Malformations predominantly on leaves. The inducers live on the surface of the malformations => 3
3a Leaves variously curled or bulging; malformations by aphids. Helianthus spp.:
3b Leaf blades of young plants over extensive parts and in various ways bent downwards, curled, and dark green close to the froth-covered nymph. Helianthus spp.: Philaenus spumarius
3c Dull white spots, pustules, even crusts on underside of leaves, largely consisting of a mass of conidia. H. annuus: Pustula helianthicola
4a Up to walnut- size or extensive, rugose proliferations on root collar or the basal stem parts. H. annuus, tuberosus, etc.: Agrobacterium tumefaciens
4b Spongy swellings of various shape on stems, petioles, leaf veins of young plants. H. annuus, tuberosus: Ditylenchus dipsaci