1927, Plant Research Institute (Canada), Annual Report of the Canadian Plant Disease Survey
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.

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.

Black canker

Meaning

Noun