black canker

Noun

 * 1) Any of several plant diseases causing the formation of dark cankers.
 * 2) * 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.
 * 1) The larva of the turnip sawfly, an agricultural pest having the appearance of a black caterpillar.