Managing the Five Most Common Apple Diseases
Don’t be afraid to grow your own apples. Sure, most varieties are rife with disease problems, but there are varietal exceptions, and smaller trees make management easier. Choosing disease-resistant apples and understanding care requirements will make for a reliably healthy harvest. Aspiring orchardists need not be discouraged.
Before and after steps can be taken to ward off common apple diseases. Preliminary steps include planting and caring for your trees correctly and applying preemptive horticultural oils and other natural pesticides. After problems appear, there are other sprays for disease management. To understand what steps to take, a gardener must be able to identify and understand each
Five Common Apple Diseases and Management
Apple Anthracnose (Neofabraea spp.): Cool, wet weather encourages this fungal disease that causes reddish or orangish circular cankers on the bark, which can open to show the interior wood. Leaf spots and bull’s-eye fruit rot are also expected features. The disease is rarely deadly. Solution: Use a strong copper-based fungicide during a rain-free spell at spring bloom and just before harvest. Remove and burn cankered branches and stems when plants are dormant in winter.
Cedar Apple Rust (Gymnosporangium
Apple Scab (Venturia
Powdery Mildew (Podosphaera
Note when you spray different pesticides. For example, copper fungicide sprays should be applied 10 days after an application of dormant oil spray. Use home pressure sprayers for application. (Click here to learn more about horticultural soil sprays and their use.)
Disease Resistant Apple Varieties
Disease-resistant apple varieties and
Newly cultivated apples are bred for disease resistance as well as flavor. These are the best apples to grow organically because they require little to no spray. Sadly, most heirlooms are very disease susceptible, though a few show some resistance. The 19th-century cultivar ‘McIntosh’ (19th century) is resistant to cedar apple rust and powdery mildew, and ‘Winesap (18th century) is resistant to cedar apple rust. Here are five of the best newer disease-resistant varieties available:
- CrimsonCrisp™: A sweet, crisp apple with deep red skin that’s highly resistant to apple scab and moderately resistant to fireblight and powdery mildew.
- ‘Enterprise‘: A firm, crisp, tart red apple with high resistance to apple scab and moderate resistance to cedar apple rust and fireblight.
- ‘Goldrush‘: A tangy, sweet golden apple with high resistance to apple scab and moderate resistance to fireblight.
- ‘Jonafree‘: A flavorful, low-acid, red apple that bears heavily and is very resistant to apple scab.
- ‘Liberty‘: A yellow and red apple that’s crisp, sweet, tart and shows great resistance to apple scab, cedar apple rust, fireblight, and powdery mildew!
All apples require cross-pollination, so you need to plant yours with compatible varieties for fruit set. (Click here to view compatible apple varieties for cross-pollination.)
Planting and Care
Plant apples in spring or fall. You can buy either
At planting time, dig a hole to the same depth as the root ball and three times as wide. Place the backfill on a large tarp or in a wheelbarrow and mix it with Fafard Premium Natural and Organic Compost at a 1:2 ratio. Sprinkle in an all-purpose tree fertilizer, using the manufacturer’s recommendations.
Center and hold the tree straight in the hole. Make sure the top of the root ball meets the lawn’s soil line. Then plant it with the amended backfill and tamp it in to remove air pockets. Water deeply after planting, filling in any low spots as they appear, and then add 2 to 3 inches of bark mulch or compost around the newly planted tree. Continue watering one or two times a week for at least two months during dry spells.
Good apple selection and disease management will leave growers with few disease worries. Apple pests are another matter, but they are often far less destructive if populations are low to moderate. Planting compact apples will make care even easier. So be daring and plant one or more apple trees this fall.
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