Plant Parasites of Europe

leafminers, galls and fungi

gallers on Alopecurus

Dichotomous table for gallers on Alopecurus

by Hans Roskam

1a On above-ground parts => 2

1b Roots with spindle-, screw-shaped or crooked galls, only a few mm long. A. geniculatus, pratensis: Subanguina radicicola

1c Roots with aphids. Alopecurus spp.: Tetraneura caerulescens

2a On inflorescences or fruits => 9

2b Complete host disfigured or malformations on stems or leaves => 3

3a Leaves or sheaths with localised or expanded malformations or with long stripes caused by smuts => 6

3b Main shoot of host stunted and disfigured => 4

4a Malformations caused by fly- or midge larvae => 5

4b Plant growth stunted. Inflorescence remains hidden in the swollen leaf sheaths, pale. A. pratensis: Limothrips denticornis

= Stem gall above internode on A. pratensis is caused by the eurytomid Tetramesa fumipennis

5a Stem shortened with weak swelling below the emerging inflorescence. A. myosuroides, pratensis: Oscinella frit

= On the same hosts the closely related Oscinella alopecuri and O. ventricosi have been described

5a Leaf sheaths usually inflated above the upper node. On stem above the nodes one or several saddle-shaped margined galls, which contain in each depression an intensely red larva. A. myosuroides: Haplodiplosis marginata

5c Yellow midge larvae develop under leaf sheaths at stem base. A. pratensis: Mayetiola alopecuri

6a Leaf blades and sheaths with smut patches => 8

6b Malformations caused by animal parasites => 7

7a Leaf sheaths inflated, bladder-like, sometimes discoloured violet and locally slightly thickened. A. geniculatus, pratensis: Rhopalosiphum padi

7b Leaf blade at base with narrow, elongate-cylindrical swellings. A. geniculatus: Unidentified eelworm

7c Upper leaf swollen, bladder-like, discoloured. Aphid up to 2 mm long, slim. A. geniculatus, pratensis: Laingia psammae

8a Elongate patches, at first lead grey, then dusty, on leaves, rarely on stems. Spores usually 2–3, in balls enveloped by sterile cells. A. aequalis, arundinaceus, geniculatus, myosuroides, pratensis: Urocystis alopecuri

8b Smut patches in black stripes, later on completely shredded leaves, on sheaths and stems. Spores solitary, globular, densely covered with small blunt warts. A. arundinaceus, geniculatus: Ustilago striiformis

8c From A. gerardii has been described: Tilletia sleumeri

9a Inflorescences disfigured over extensive areas => 11

9b Malformations predominantly restricted to ovaries and neighbouring glumes => 10

10a Infected ovaries transformed into a compact smut body, sometimes larger than a normal seed. A. myosuroides: Tilletia controversa

10b Ovaries swollen, tube-shaped elongated, inside with spongy tissues or with expanded cavities. Glumes ± conspicuously enlarged. A. alpinus: ? Anguina sp.

10c Seeds destroyed on account of the puncturing of the ovary by the larva. A. agrestis, pratensis: Dasineura alopecuri

10d Midge larvae live gregariously in inflorescences. A. pratensis: Contarinia merceri

10e Ditto, A. arundinaceus, geniculatus, myosuroides, pratensis: Stenodiplosis geniculati

11a Spikelets variously completely or partially disfigured by aphids. A. arundinaceus, pratensis: Sitobion avenae

11b Similar malformations. A. arundinaeus, pratensis: Sitobion fragariae

11c Spikes leafy, over expanded parts ± greened or, in case of strong infestation, bleached. A. pratensis: Aceria tenuis

Last modified 5.iv.2020