Diseases and Pests
To prevent disease, plant resistant varieties, practise good garden sanitation and improve the quality of your soil. When the tree has no leaves and before the buds start to open in spring, spray with dormant oil, which contains lime sulfur, to kill overwintering insects and fungal diseases. Ideally apply two or three times. However, trees must not be treated or be wet with dormant oil when the temperature is below freezing. On the West Coast, treat trees after the leaves fall, in mid-winter and before the buds start to open in spring. In colder areas, spray only when temperatures allow.
Protect against sun scald and damage by small mammals by installing tree guards on young trees, but not too tightly, as they can inhibit growth and cause the bark to stay moist, encouraging disease. It's best to put guards on in fall and remove them for the growing season. Once the tree bark is rough, guards are no longer necessary.
Apple Maggot The adult fly lays its eggs on the fruit and the larvae tunnel into the apple. To prevent these pests from overwintering, pick up and dispose of fruit as soon as possible after it drops. During the growing season, trap adults by hanging sticky red sphere traps (available at garden centres). Put in place three weeks after petal fall.
Codling Moth The adult moth lays its eggs on the leaves and twigs, and the larvae soon move to the fruit and tunnel inside. As long as there are no untended fruit trees within 90 metres, trees can be effectively protected with codling moth traps, which are available at garden centres. Place in the trees as soon as bloom begins. For serious infestations, spray with Bacillus thuringiensis 15 days after petal fall begins, then five days later and once again after another five days.
Curculio The tiny adult beetle lays it eggs on the fruit and the larvae tunnel into the apple. When the larvae start feeding, the fruit drops and the larvae crawl out and burrow into the soil. Rake up leaves in fall and remove brush piles and other debris near the trees. If curculios are a serious problem, spread a sheet under the tree each morning for three weeks after petal fall and shake the tree. The adults, which play dead when alarmed, will fall onto the sheet.
Scab A fungal disease resulting in olive-coloured spots on leaves and fruit; spots darken over time. Leaves may drop off, and lesions on fruit turn hard and corky. Spores overwinter on infected leaves, so do a good fall cleanup. Plant disease-resistant varieties such as ‘Liberty', ‘Freedom' and ‘Novamac'.
Cedar Apple Rust Small, rust-coloured pustules form on the undersides of leaves. Control with a sulfur spray when the buds have a pinkish tinge and again three weeks after petal fall.
- ‘Cortland' Great flavour; uses: fresh, baking. Stores very well. Late; Zone 4
- ‘Empire' Dark red, high quality; uses: fresh, baking. Late; Zone 4b
- ‘Freedom' Large, red; immune to many fungal diseases; uses: fresh, baking. Late; Zone 4b
- ‘Golden Delicious' Sweet, high quality; uses: fresh, baking. Late; Zone 5
- ‘Greensleeves' Has the green skin and crisp tartness of ‘Granny Smith', but greater hardiness; uses: fresh, baking. Late; Zone 4b
- ‘Liberty' Juicy, red; very disease-resistant; uses: fresh, baking. Stores well; highly recommended. Late; Zone 4
- ‘Lodi' An improvement on ‘Yellow Transparent', green-yellow; use: baking. Doesn't store well. Early; Zone 4
- ‘Novamac' Red, high quality; good disease resistance; use: fresh. Late; Zone 4b
- ‘Paulared' Flavour is similar to ‘McIntosh'; use: fresh. Early to midseason; Zone 4
- ‘Spartan' Quite scab-resistant; uses: fresh, baking. Stores well. Late; Zone 4
- ‘Cox's Orange Pippin' Exceptional quality, orange-red; use: fresh. Late; Zone 5b
- ‘Duchess of Oldenburg' Green-yellow splashed with red; use: cooking. Scab-resistant. Early; Zone 3
- ‘Golden Russet' Uniquely flavoured, aromatic, golden brown skin; uses: fresh, cider. Stores well. Late; Zone 4
- ‘Snow' (a.k.a. ‘Fameuse') 300-year-old Canadian variety; aromatic, sweet; use: fresh. Midseason, Zone 4
- ‘Wealthy' Juicy, aromatic, red with white flesh tinged with red; scab-resistant; uses: fresh, baking. Midseason; Zone 3
- ‘Wolf River' Huge, hardy and healthy; uses: baking, fair for fresh. Late; Zone 3
- ‘Yellow Transparent' Yellow; uses: long-time favourite for baking and sauces; somewhat scab resistant. Earliest apple; Zone 3