Plant Parasites of Europe

leafminers, galls and fungi

gallers on Papaver

Dichotomous table for gallers on Papaver

by Hans Roskam

1a On parts above ground => 2

1b Roots with nodular swellings. P. argemone, rhoeas: Meloidogyne hapla

1c Cyst -developing eelworm in hardly disfigured roots. Papaver sp.: Heterodera schachtii

2a On flowers and fruits => 6

2b On vegetative organs => 3

3a Malformations caused by animals => 4

3b Malformations caused by fungi. Leaves of often completely diseased and severely stunted young plants narrowed, pale and thick. Partially infected young leaves on usually expanded infestation area yellow-green, between veins bladder-like swollen, fleshy thickened, the margins rolled downwards and on underside covered with a dense, white-grey to pale violet down of conidiophores. Diseased flower- or capsule stalks, variously distorted due to stunting; buds and capsules crippled and disfigured. P. dubium, rhoeas, somniferum: Peronospora arborescens

3c Similar malformation, mainly on leaves. P. argemone: Peronospora argemones

4a Malformations caused by aphids and spittlebugs => 5

4b Midrib of rosette leaves stunted, especially at base, spongy thickened; leaf blades ± nested, curved; young axial parts basally greatly shortened or with local, ± distorted pale swellings. Papaver spp.: Ditylenchus dipsaci

4c Stem from the outside not disfigured; many rotund, thin-walled galls inside; “cryptocecidia”. Each gall containing a single larva. P. bracteatum, lasiothrix, pseudoorientale, somniferum: Iraella luteipes

4d Midge larvae developing in stems of P. nudicaule: Karshomyia caulicola

5a Complete plant disfigured; leaves rolled downwards, curled, ± discoloured. Papaver spp.: Aphis fabae

5b Leaf blade strongly deflected, curled and deep green close to the froth-covered nymph. P. orientale, rhoeas, somniferum: Philaenus spumarius

6a On or in fruit capsules => 7

6b Double flowers. P. alpinum: Unidentified gall mite

6c Flower buds transformed into a rosette of short leaves and bracts wrapping an irregular globular area with a plurilocular gall containing 2‒6 cells, flowers aborted. P. dubium, rhoeas: Iraella hispanica

7a Galls not or hardly visible from the outside => 8

7b Large parts or complete capsule strongly swollen and disfigured. Septa absent or reduced to short ridges. Tissue inside capsule soft, towards margin ± cracked with many tough-walled larval chambers. P. argemone, dubium, rhoeas, somniferum: Aylax papaveris

8a Tough walled, small, white galls located on the septa, up to 2 mm long, developing from seed primordia. Containing a single white larva. P. argemone, dubium, hybridum, rhoeas: Aylax minor

= Inquiline cynipid wasp: Parnips nigripes

8b Between strongly swollen septa of sometimes ± distorted capsules live many orange-red midge larvae. P. argemone, dubium, fugax, rhoeas, somniferum: Dasineura papaveris

Last modified 26.iv.2020