English Dictionary

black canker

noun

Any of several plant diseases causing the formation of dark cankers. / The larva of the turnip sawfly (Athalia rosae), an agricultural pest having the appearance of a black caterpillar.

Black canker is a disease that affects fruit trees.

意味（1）

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

Scab and black canker is rapidly destroying Salix vitellina in Nova Scotia. Ten per cent of the trees surviving from previous years were killed. The damage caused by these two diseases can not be estimated separately.

意味（2）

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.