Apple Trees: 4 Common Diseases, Varieties, and More

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apple trees

Do you know that Apple Trees are some of the most susceptible plants to diseases?

Moreover, apple trees are as lovely as in bloom as any other ornamental flowering tree and these blooms are often fragrant.

But unlike any other ornamentals, they also give you a delicious harvest of fruits.

Not all apple trees are limited to their landscaping use, a row of them can also act as a privacy screen all summer and fall, while fully leafed out.

YOu can choose among different varieties of apple trees, like dwarf varieties that grow up to 5 to 8 feet tall, and semi-dwarf varieties that can grow 12 to 16 feet tall.

Apple trees and other plants in the rose family, such as hawthorns are susceptible to a number of plant diseases.

However, the good news is that these diseases are often preventable and even when they are not, the damage they cause is at an aesthetic level.

Let’s learn more about them in detail.

Apple Tree Diseases

One of the important things to note is that if you are a large-scale grower, then you cannot tolerate the damage that comes with plant diseases on your apple trees.

This is because your fruit needs to look good to be marketable.

While if you are a small-scale grower, then you can tolerate such damage.

Learning to identify the most common apple diseases is the first step in handling the worst-case scenarios.

However, you can avoid such situations altogether by buying certain cultivators and/or practicing sound horticultural hygiene.

It is important to note that fungi are at the heart of some of the most common apple tree diseases.

In such cases, if you are a small grower, prevention is one of the preferable ways to treat your trees after they get infected via fungicidal sprays.

apple trees 1

As fungi spread from infected plants to healthy ones through airborne spores and thrive in wet conditions, preventing it involves:

  • improving soil drainage,
  • proving proper spacing
  • removing the diseased plant of the parts as soon as possible.

However, if you are a large-scale grower, then you need to use fungicides.

This can vary in terms of effectiveness.

If you do decide to apply a fungicide treatment, then first check with the local country extension, as spraying schedules can often be complicated.

Additionally, practicing good garden hygiene, like removing fallen leaves in autumn, can prevent these fungi through proper plant selection.

Now let’s discuss some common apple tree diseases.

Apple Scab

In the case of apple scab, the fungus responsible is Venturia inaequalis.

The first sign you will notice of apple scab is in the form of a lesion on the new leaves of the tree, either in early spring or mid-spring.

Moreover, this lesion will be darker than the color of the leaf, found on the underside of the lead which is light green.

These lesions will often be olive-colored and on top of the leaf, which is a darker part, lesions will be of black color.

It is important to note that infected leaves may fall off altogether in summer.

If the tree, however, still manages to produce fruit, the apples will also have dark, scabby lesions.

apple scab

Fortunately, the apples are edible, just peel off the skin before eating.

In case you are a small-scale grower, you can prevent apple scabs easily as the cause is simply lack of observation and poor hygiene.

An infection often starts with small and even goes unnoticed.

The real problem, however, begins when you allow the infected leaves that fall to the ground at the end of the growing season to remain there.

Venturia inaequalis overwinters in this fallen, infected foliage and uses it as a space for spring invasion.

Moreover, rainy weather provides ideal conditions and the fungal spores blow up onto the new leaves, thus infecting them.

Learn more about Garden Pests here.

Powdery Mildew

The fungus responsible for this disease is Podosphaera leucotricha.

Even if you are growing apples for the first time, you would probably know this disease because they often tend to infect ornamentals plants.

These often include garden phlox.

Moreover, it is unlikely to kill your plant, however, it will spa its strength. You can easily recognize this disease.

Powdery mildew is recognizable as a whitish powder that coats the leaves of many garden plants.

In such ad cases, you can trace the cause back to the last year’s garden even if you did not notice it.

powdery mildew

This fungus overwinters in fallen, infected leaves, its spores blow up onto healthy leaves, thus infecting the healthy leaves.

However, insects can also be the cause of the spread of healthy plants.

Even a heavy storm can be the culprit, as a pounding rain can send the spores flying up to the leaves of the trees.

In order to prevent them, other than cleaning up the fallen leaves in autumn, you can follow the spacing requirements indicated by the plant labels.

This will help to make sure good air circulation and to avoid overhead watering.

Cedar-Quince Rust

The scientific name for this fungus is Gymnosporangium clavipes, which often needs a host plant to attack your apple trees.

For instance, if you are growing flowering quince shrubs, or Chaenomeles speciosa, which is another member of the rose family in your landscape, they can serve as hosts.

Moreover, it will spread from them to your apple trees.

The major sign of this ingestion is the presence of rusty spots on the leaves of your tree. The apples themselves may also be misshapen and/or suffer from mottling.

rust

If you grow a type of plant that can serve as a host, you can also look for the sign that the host is carrying the disease, i.e. rust galls.

These will often sprout orangey-rusty “horns” in spring that send out sores to attack your apple trees.

In order to prevent rust, you need to get rid of the host plant. Moreover, make sure to grow rust-resistant apple cultivators.

Phytophthora Rots

A fungus-like disease that can affect the strength of spas of your apple tree is Phytophthora.

Moreover, this disease can attack different parts of your trees, including the trunk or the roots.

In case you suspect the apple tree infestation with this disease, perform the same test you would if you see an arborvitae shrub, either dead or alive.

For this test, take a sharp knife and remove a small strip of the outer bark of the trunk to check the color underneath.

Healthy wood tends to be green hear, while if there is an infestation, the wood will be orange or brown.

In most cases, the cause of this disease is contamination, which comes from the soil you bring on your property, irrigation water, or even the plant itself.

phytophthora, apple trees

It can also happen if you do not bring the soil from a reputable nursery.

To prevent this disease, be very careful to avoid any type of contamination, take moisture-related precautions, just like you would for fungus prevention.

This is because Phytophthora also thrives in moist conditions.

For instance, plant on landscape berms or in raised beds at ground level to improve drainage.

Additionally, when buying, make sure to look for a tree with Geneva series rootstock, as it will have superior resistance.

Varieties of Apple Trees that are Disease Resistant

You don’t want to be one of those who let their taste buds make the decision for growing fruit trees.

You might want to grow plants that are low-maintenance, however, disease-resistant plants or a variety of apple trees can also prove to be beneficial.

The above 4 diseases, i.e. apple scab, cedar apple rust, powdery mildew as well as fire blight are common apple tree diseases.

In order to avoid these diseases or at least reduce the chances of infestations, you can choose amongst the following varieties of apple trees:

  • enterprise
  • liberty

apple trees2

 

  • freedom
  • redfree

Moreover, cultivators that are resistant to Apple Scab are Crimson Crisp, Gold Rush, and Mac-Free.

Apple tree types that are resistant to powdery mildew are Liberty and Gold Rush.

Varieties resistant to rust are Redfree, Willaim’s Pride, and Freedom.

While to avoid Phytophthora Rots, you can have apple trees that say Geneva series rootstock.

Selection by Climate and Taste of Apple Trees

Other than the consideration of dwarf vs. standard varieties, the first and foremost thing you need to consider is one of the varieties of apple trees to make sure they grow best in your region.

Your local country extension office can provide you with this information.

The following examples of varieties that can grow in zones 3 to 8:

  • Golden Delicious
  • Cortland
  • Haralred
  • Honeycrisp

After understanding which varieties you can grow, the next question is which one you want to grow.

For this part, you will need to rely on your taste buds, or sample fruit from the varieties of apple trees can help to learn which one you want to grow.

Moreover, you can consider both, your taste, i.e. sweetness or tartness, and the texture of the apples.

This is because some of you care more about the crispness of the fruit rather than its taste.

It also matters how you intend to eat them, either in terms of pie. These can be the following:

  • a sweet fruit, grow Honeycrisp.
  • tart fruit, grow Granny Smith.
  • crisp fruit, grow Macoun.
  • pie-making, grow Northern Spy, Liberty, and Golden Delicious.

Final Thoughts

Though with the help of certain preventive measures, and planting disease-resistant varieties, you can have healthy plants, however, you still have pests to worry about. To avoid scales, miles, and aphids, you can use horticultural oil on apple trees after the bloom is over.

Spray every 10 to 14 days. However, for apple maggot, codling moths, green fruitworms, and plum curculios check with your local extension for pesticide speary in your area. However, you can also use neem oil as an organic alternative for curculio control.

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