gallers on Phalaris

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