Plant Parasites of Europe

leafminers, galls and fungi

gallers on Cucumis

Dichotomous table for gallers on Cucumis

(inc. Citrullus)

by Hans Roskam

1a On parts above ground => 4

1b On roots or on root collar => 2

2a On roots => 3

2b Several shoots on root severely stunted, thickened, developing into a compact “leafy gall”: Rhodococcus fascians

3a Small solid swellings, often curved and twisted, at tips of lateral roots; other parts of root sometimes thickened; eelworms live externally in soil, not often seen. C. sativus: Xiphinema diversicaudatum

3b Roots with small nodular to spindle-shaped swellings, occasionally with side roots. C. melo, sativus: Meloidogyne hapla

4a Malformations of leaves caused by aphids => 5

4b Nodular swellings on stem, twigs and roots. C. melo: Eriosoma lanigerum

4c Development of young plants severely stunted. Lower stem parts shortened, irregularly spongy, swollen, plants often with increased development of often similarly disfigured lateral shoots. Later infestations result in locally ± confined pale green, spongy swellings on stems, leaves and even young fruits. C. melo: Ditylenchus dipsaci

5a Leaf blades disfigured and curled. Aphids lighter to darker green or yellowish => 6

5b Aphids black. Cucumis spp.: Aphis fabae

6a Aphids lacking frontal protuberances on head; siphunculi cylindrical or weakly conical => 7

6b Protuberances on head present. Siphunculi weakly club-shaped. Body glossy, greenish-yellow to green or reddish. Cucumis spp.: Myzus persicae

7a Apterous aphids dark-spotted to dirty yellow. Siphunculi black, slightly conical. Cucumis spp.: Aphis gossypii

b Apterous aphids yellow to greenish-yellow. Siphunculi yellowish-green with brownish tip. Cucumis spp.: Aphis nasturtii

Last modified 25.iv.2020