Plant Parasites of Europe

leafminers, galls and fungi

gallers on Castanea

Dichotomous table for gallers on Castanea

by Hans Roskam

1a Malformations on parts above ground => 2

1b Considerable, ± rotund, broadly attached cancers close to the root collar. C. sativa: Agrobacterium tumefaciens

= Cancers observed on stems of young trees might, according to older references, be attributed to Diplodina castaneae

2a Galls caused by animals => 4

2b Stems with local, ± expanded swellings caused by mistletoes => 3

3a Evergreen mistletoe on spindle-shaped swelling. C. sativa: Viscum album

3b Deciduous mistletoe on slightly thickened branches, “woody roses”. C. sativa: Loranthus europaeus

4a Galls on young twigs, on leaf petioles or on the midrib of the leaves, unilocular or multilocular, 5–20 mm in diameter, green or rose-coloured, often including portions of developing leaves, stems and petioles. The gall dries, becomes wood-like, and remains attached to the tree for up to two years. C. crenata, dentata, mollissima, pumila, sativa, seguinii: Dryocosmus kuriphilus

4b Rotund pustule, about 1 mm across, slightly protruding on both leaf surfaces. Pustule paler than surrounding leaf blade. C. sativa: Unidentified gall midge

4c Bark of the two-year old and perennial twigs, usually on the underside with expanded, 2–3 mm thick, later with longitudinal fissures bursting proliferations of the cambium. C. sativa: Lachnus roboris

Last modified 1.ix.2022