Plant Parasites of Europe

leafminers, galls and fungi

gallers on Phalaris

Dichotomous table for gallers on Phalaris

(incl. Phalaroides)

by Hans Roskam

1a Malformations on or in inflorescence, flowers or fruits => 11

1b Malformations of vegetative parts => 2

2a On leaves and culms => 3

2b Roots with half screw-like or crooked swellings. Phalaroides arundinacea: Subanguina radicicola

3a Complete plant disfigured, or malformations restricted to shoot tips or leaves => 7

3b Galls on culm => 4

4a Larvae between culm and leaf sheath => 5

4b Culm weakly swollen at upper internodes. Larva inside the stem. Phalaroides arundinacea: Tetramesa sp.

5a Midge larvae, lacking black mouth parts => 6

5b Larvae with black mouth parts, usually with several larvae inside the slightly swollen internode at base of an occasionally severely stunted and ± bleached inflorescence. Phalaroides arundinacea: Oscinella trochanterata

6a Culm above the node, underneath the leaf sheath, with several oblong-oval, flat, slightly rimmed depressions, each containing a single orange-yellow larva. Phalaroides arundinacea: Lasioptera calamagrostidis

6b Culm above the node with strong, sometimes almost saddle-like rimmed depressions. Larvae white to golden-yellow. Phalaroides arundinacea: Mayetiola phalaris

7a Complete plant severely stunted or apical leaves distinctly gathered together => 9

7b Malformations of leaf blades and -sheaths => 8

8a Aphid gall. Leaf sheath inflated, ± discoloured, leaf blade twisted, rolled. P. canariensis; Phalaroides arundinacea: Rhopalosiphum padi

8b With similar damage. P. canariensis: Sitobion avenae

8c Long parallel stripes caused by smut, especially on the upper leaves of the ± shortened shoots. Sori also on leaf sheaths, with dusting of blackish olive-brown spores. Panicles reduced, often remaining in sheaths. Phalaroides arundinacea: Ustilago echinata

8d In addition, same host, may occur the rare fungus: Physoderma graminis

8e Leaves curled and wrinkled; culms often severely distorted. Phalaroides arundinacea: Ustilago serpens

9a Malformations without conspicuous accumulation of apical leaves => 10

9b Plant severely stunted. Leaves terminally accumulated. Upper culm containing a single whitish larva. Phalaroides arundinacea: Tetramesa sp.

10a Young shoots often severely stunted in longitudinal growth; swollen at base sometimes slender onion-like. Developing shoots ± strongly shortened, often with many ± distinctly rimmed depressions above the nodes; shoots that continue to grow mostly bleaching. Often with large numbers of larvae per shoot. Phalaroides arundinacea: Mayetiola phalaris

10b Mites are vagrants at the upperside of the leaves and in the leaf sheaths. At higher densities the leaves may become discoloured and rolled. Phalaroides arundinacea: Acaralox arundinaceus

11a Malformations mainly of ovaries, fruits => 12

11b Inflorescence disfigured; flowers stunted, variously disfigured or bleached. Phalaroides arundinacea: Aceria tenuis

12a Ovaries slightly swollen, filled with brown spore masses. Phalaroides arundinacea: Tilletia menieri

12b Spikelets disfigured, ovaries enlarged, ± bottle-shaped. Often found associated with the fungus Dilophospora alopecuri. Phalaroides arundinacea: Anguina agrostis

12c Orange coloured midge larvae feed solitarily on developing ovaries. P. minor; Phalaroides arundinacea: Sitodiplosis phalaridis

12d Yellow gall midge larvae prevent the formation of seeds. Phalaroides arundinacea: Coniophora graminicola

Last modified 18.iv.2020