Apple Tree Diseases

Apple Tree Diseases: How to Treat Them

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This time we will talk about apple tree diseases. After we have all our power to grow apple trees and want to harvest lots of apples in the garden, of course we don’t want to lose a lot of apples due to disease or pests. Apple trees are often infected with diseases and can even be transmitted from one apple stem to another. Some types of diseases can still be treated with good and proper handling, while some other types of diseases cannot be treated at all. So, we must quickly identify the disease and prevent it from spreading to other plants.

Here we will explain about apple tree disease, symptoms, prevention, with the aim that apple farmers can produce lots of apples.

What Is Apple Tree Disease and How to Treat It

1. Apple Scab Disease

One of the apple tree diseases is Apple Scab, and this disease can infect the McIntosh, Cortland, and Macoun species.

The symptoms that appear are olive green dots or brown spots on apple leaves. Then the leaves will curl and eventually fall off. Likewise apples, dark green spots appear, dark and turn into scaly, some even cracked. Infection with this disease can cause fruit to fall and can inhibit the formation of new flowers.

What causes this disease? The cause is spores that escape from apple leaves, fall to the ground during winter, then these spores infect other apple plants that are close to it. This condition will get worse if there is continuous rain.


Take the infected apple leaves and remove or move them to another place in May. If you must uproot an apple tree, then remove it from your garden or burn the trunk for firewood. The University of Maine Cooperative Extension provided a solution to this, they mentioned using preventive sprays such as sulfur, fungicides and captan.

Infection can occur as early as Mai or when green tissue appears at the top. Throughout the rainy season, this disease will continue to spread.


Apple scab disease rarely kills apple trees. In severe cases, apple scab disease can cause defoliation in early summer. If this infection occurs continuously it can weaken the apple tree, and this makes your apple tree susceptible to various diseases.

2. Sooty Blotch and Flyspeck

Apart from apple scab, there is also an apple tree diseases called Sooty Blotch and Flyspeck. This includes dangerous diseases. To date, no apple tree is known to be immune to this disease.


Among the symptoms of Sooty Blotch and Flyspeck is a fungus that grows on the surface of the apple. This disease causes stains on the surface of the apples but does not damage the apples. These diseases often appear together in late summer.

Flyspeck is a fungus that appears coiled up on apples and is formed with small, distinct black dots. Sooty blotch forms irregularly shaped, olive green spots also appear on the surface of the apples.

After infection, this disease does not appear immediately, it takes a month to appear and appear clearly on the surface of the apple. Sooty blotch and flyspeck usually appears on dewy apple plants or apple trees that are not protected from high humidity. Apple trees with lots of morning dew are also the target of this disease.

What causes sooty blotch and flyspeck

The fungus that causes apple tree diseases is overwintering in the twigs of apple, pear, and woody plants. These spot spores spread to apples during the rainy season, they also spread into the air and it affects the surrounding apples.

Treatment of sooty blotch and flyspeck

One of the apple tree treatments for this disease is as recommended by UMaine Cooperative Extension. They apply fungicides from mid to late July. This implementation will be carried out again in August. At this point prune the apple plant and remove a few branches to allow air to enter.

The development of this disease will occur from August to September. The humid weather in this season will encourage the appearance of the sooty blotch and flyspeck.


This disease does not cause the apples to rot. Apples that have an impact are still safe to eat. It’s just that, the shape and color of the fruit no longer look fresh.

3. Cedar Apple Rust Disease

Cedar Apple Rust is an apple tree diseases that is prone to attack the Golden Delicious. However, there are several varieties of apples that are resistant to this disease such as Enterprise, Black Oxford, and William’s Pride.

The symptom of this disease is the appearance of yellow or orange spots on the leaves that are 1/4 inch in size. Over time, these spots then spread to the center of the leaf.

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Cause Cedar Apple Rust

This is a disease that occurs when apple trees are planted near eastern red cedar and other types of juniper. These apple, juniper and eastern red cedar trees can spread disease between one another. So make sure you plant apple trees away from these types of plants to avoid possible cedar apple rust.

Throughout the winter, the fungus infects apple branches and galls on juniper trees. While in the spring, galls produce gummy, orange and gummy and this causes spores to be wet. These spores are then carried by the wind to a distance of 1 mile and hit the apple tree, this then causes your apple to become infected with disease. Then, in the summer, these spores then develop even more viciously and develop red spots on the upper scaly. These infected apple trees will then release these spores to hit your juniper and red cedar trees. That is what is called by infecting one another.

Cedar Apple Rust Treatment

For the treatment and prevention of cedar apple rust, UMaine Cooperative Extension recommends using a fungicide that contains phenarimol or myclobutanil. So, the most important step is not to plant the host tree close to the apple tree. Check to see if your juniper and red cedar are infected with spores, pruning off the branches in early spring and removing the galls.

This apple tree diseases spreads during certain seasons, usually from April to mid-June.

This type of disease does not cause severe damage, but is very disturbing to your apple tree.

4. Powdery Mildew

Another apple tree diseases is Powdery Mildew. This type of disease infects several types of apples such as: Jonathan, Jonagold, Bonza, Elstar, Lady William, Pink Lady, and Gala apples.

The symptom of this disease is a fungus that causes a white color on the leaves, this grayish white color can cause resistance to apple plants. This can cause the apple tree to grow kerdir, and the flowers that do not bear fruit, as well as the leaves and shoots sometimes turn brown in the summer.

The cause is the fungus present in the infected shoots over the winter. When spring comes, these buds open and they are covered with powdery spores. These spores are carried by wind and can infect the fruit, leaves and shoots of apples.

Powdery Mildew Treatment

Infected branches and twigs are pruned at the start of the season. However, if the disease looks severe, you can use a gungicide.

This apple tree diseases likes hot as well as dry conditions. It spreads when buds open in the spring. This fungus does not kill the apple plant, but it inhibits fertilization which results in decreased apple production.

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5. Black Rot

Some types of apples infected with black root disease are Empire and Cortland.

Symptoms of black rot are the appearance of frogeye leaf spots, rot on the fruit, and canker appearing on the branches. Apple leaves that are exposed to black rot will form spots like frog eyes. The edges are reddish and the center is brown. These brown, rotting spots are very common at the tips of the flowers. This disease causes the apples to shrink and dry out but still stick to the tree.

The cause of black rot is fungus. The fungus attacks the trunk, fruit and branches. Spore-producing structures called Pycnidia develop on exposed (infected) fruit. it appears as small black spots, when wet and cold conditions and winds carry the spores to other areas. This fungus can infect leaves, wood and fruit, through existing wounds. Apple trees are particularly susceptible to black rot when they are infected with fire blights.

Black rot treatment

Burn any infected branches or twigs, as well as any dried fruit. Everything is buried or burned to get rid of the diseases that exist in the branch. If you are destroying an apple tree, pluck the roots to make sure no spores are left. To overcome this blak rot do not use fungicides. However, you can use captan and sulfur products specifically produced to fight black rot. Prevent the formation of blight as it is a very susceptible cause.

The University of Minnesota Extension says that these leaf spots are not very harmful to apple plants. It doesn’t affect the health of the apples, but it can be a problem with apples if the leaves turn yellow and fall off. Take precautions and treatments for impacting apple trees as soon as possible.

8. White Rot

White rot is a type of apple tree diseases that infects Golden Delicious, Jersey Mac and Empire apples. This type is susceptible to being compared with other types.

White rot or also known as “bot rot”, is a disease that infects apples caused by a severe fungal pathogen. It infects the twigs and legs, this is especially evident in the summer where the spots are small blisters. White rot infects the apples and stems, but it does not infect the leaves. If infected, the wood will be soft and the red fruit will fade.

Causes of white rot are dryness, winter injury or stress. Black pycnidia, or spore-producing structures develop on the surface of the cankers. From the fruit structure, spores come out and infect the injured stem, causing rot.

How to treat white rot

The treatment of apples from this disease is to remove any wood that is wilted and soggy. Trim dead wood and make sure the trees don’t stress. Remove blighted wood and water trees during times of dryness. This will keep the apple plant from stressing out.

This is an apple tree diseases that is common at the end of the season.

Be careful with this disease, if it attacks the apple tree, you may experience a 50% decrease in apple production. So, if you see symptoms of “white rot” on an apple tree, take precautions and treatment right away.