black canker

Definitions

1. 1

   Any of several plant diseases causing the formation of dark cankers.

2. 2

   The larva of the turnip sawfly (Athalia rosae), an agricultural pest having the…

   The larva of the turnip sawfly (Athalia rosae), an agricultural pest having the appearance of a black caterpillar.

   • Among the numerous enemies to which turnips are liable, none have proved more fatal here than the black canker (a species of caterpillar) which in some years have been so numerous as to cut off the farmer's hopes in a few days.
   • In some seasons these pests are exceedingly numerous, and in the Eastern Counties the “Black Canker,” as it is called, lays waste entire fields of turnips.

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