My blackberry plants (planted in spring 2008) have recently developed a white cotton-like attachment to the underside of some of the leaves. Should I be concerned? If yes, how do I treat?
Certified GKH Gardening Expert
It sounds like you have spider mites. This article should help: https://www.gardeningknowhow.com/plant-problems/pests/spider-mite-detection-and-spider-mite-natural-control.htm