Curing apple scab
A reader from Prince Edward Island writes:
We have five beautiful apple trees and this year hundreds of pounds of apples fell from the tree with an infestation of “apple scab," I believe. I looked at the markings and compared them to a book on gardening that identified it to be “apple scab” – the result of a small fly that lays eggs in the tree in the fall that gradually make their way to the apples in the spring. A beautiful crop of juicy red apples – wasted!
Please help us save the tree, the apples, and if it’s OK, to waste some apple flies. I would like to know how to keep these pests away before next spring. I do have some insecticide but want to stay away from that sort of thing.
David Suzuki’s gardening expert Lisa Atkins consulted with Martin Harcourt of Mainland Landscaping who writes:
Apple scab is a fungus that survives over winter in leaf litter and on the branches and fruit left on the ground, so sanitation is very important. All leaves should be taken away and incinerated, or taken far enough away down wind to compost.
Lesions on the tree limbs should be pruned out aseptically – that is, the pruning equipment is dipped into a weak hypochlorite solution or vinegar and water (about a cup to a five gallon pail) in between cuts. Prune off a lesion and dip the pruner, saw off a branch and dip the saw. After the pruning and sanitation the tree should be sprayed with dormant oil lime sulphur – usually three applications, three days apart.
Tags: apple scab, apple trees, flies, fruit trees, fungus, gardening, prune, vinegar, winter