Common Cherry Tree Diseases and Insect Infestations

The cherry tree has a long and colorful history, and this bright tree is very popular with homeowners and business owners because cherry tree diseases are relatively easy to treat and spot. There are several species of cherry trees available, and the cherry trees produce the eye-catching pink flowers when they bloom in the spring. 

This tutorial will walk you through the common cherry tree diseases and what you can do about them.

The History of Cherry Trees 

In 1912, Tokyo’s Mayor, Yukio Ozaki gifted 3,000 cherry trees to Washington, D.C. This gift was to honor the friendship between Japan and the United States. Viscountess Chinda and First Lady Helen Taft planted the first of the 3,000 cherry trees in the West Potomac Park on the Tidal Basin’s north bank.on March 27, 1912. 

The United States repaid the gesture three years later by sending Japan flowering dogwoods. When a group of schoolchildren reenacted the cherry tree planting, this began the nation’s annual Cherry Blossom Festival. Japanese Prince Takamatsu came to the United States four years later on his honeymoon. 

Shortly after Pearl Harbor, vandals cut down some of the biggest cherry trees during the middle of the night. China and Korea claimed that the United States had stolen the trees from them, and they claimed that the United States should change the tree’s name to the Korean Cherry Tree. Japan’s war damaged their cherry trees, and they requested the United States to help them bring the grove back. The U.S. sent budwood back to Japan in 1952. 

Around 70% of the blooms open in Washington, D.C. each year starting March 26th and going until March 30th. During this time, there are kite festivals, parades, bike rides, fireworks, and luncheons. You can walk through the cherry trees and find out about their history. Japanese poetry is also offered, or you can take a quiet walk and surround yourself with the beauty of these cherry trees. 

The annual Cherry Blossom Festival draws thousands of visitors each year to the Washington, D.C. area. 

What Cherry Trees Look Like

Before you spot cherry tree diseases, you have to understand what cherry trees look like. Many people confuse these trees with plum and peach trees. However, there are several distinct points that will help you identify these trees, and this will also help you spot the diseases. 

Fruit and Flowers 

The flowers come in pink or white, and the flowers don’t have a scent. Every flower stalk emerges from a centralized point, and they grow in clusters. The flowers come with long stamens that will poke up from the center of the flower. The way the flowers cluster is one way to quickly distinguish the tree. They flower in early spring before producing pale green berries. 

Some ornamental cherry tree species don’t produce fruit. If yours does, they’ll grow in clusters or pairs. They hang where the flowers were, and they’ll be pale and small at first. In the late summer months, the fruit will get redder and larger, but they could also be black or yellow. 

Although cherries come in several colors, the deep red coloring is the most common.

Leaves and Bark 

The tree has toothed leaves in an oval shape. The tip has a point, and they can grow between two and five inches long. A lot of varieties have leaves that arrange alternately on all of their branches, and they’re shiny and large. The leaves can turn a pale yellow as they go up the tree. 

The bark can be gray, brown, or a mix of the two. It features horizontal lenticels, and these markings are lighter in color and look like dozens of small cuts. The bark may peel back in some places, and you should see a darker shade underneath it. It’s very hard, but it can get softer as you go up the tree. 

Shape and Grafting 

Cherry trees have a unique shape when they’re mature. They’ll form an umbrella shape when the branches spread and make the top look wider than the bottom. For contrast, pear trees have a teardrop-shape, and plum trees look oval or round. 

If people want cherry trees to produce fruit, they’ll graft them. You’ll find these graft on the trunk, and it should be right where the first branches come out. Other types of fruit trees have their grafts on the branches themselves, and this lends a knotty look to them. 

Cherry Tree Diseases and Insects

Although these trees are beautiful, cherry tree diseases can devastate them if you don’t catch them and treat them quickly. This is why it’s so important to know what a healthy cherry tree looks like. Cherry tree diseases have bacterial and fungal origins, and different species are more susceptible to specific diseases and insect infestations than others. 

There are numerous things that could attack your cherry tree, but many of them have specific symptoms associated with them.

Cherry Tree Diseases – Bacterial Origins

First up, we’re going to go over several cherry tree diseases that come from a bacterial infection. This is more rare than fungal infections or insect infestations, but it can be no less devastating. Cherry tree diseases that come from bacteria are slightly more difficult to spot. 

Bacterial Canker

Cankers form on the cherry tree’s leaf buds, flower bases, in spur bases, in pruning wounds, and at the bases of twigs. They slowly start to spread upward once they form, and they create sunken areas in your cherry tree in the cooler winter months. If this bacteria makes it into the dormant flower buds, it can kill them before they open. It could also allow the bud to open before collapsing in the middle of the summer. The bacteria that forms these cankers favor low temperatures with higher moisture like you get in the springtime. Trees that grow in sandy soil, trees that are young, and trees that have poor drainage are very likely to develop them. 

To prevent this cherry tree disease, make sure you match your cherry tree’s environmental needs to your climate. If you do, this will reduce the tree’s stress levels, and this is one big thing that encourages it to develop. Prune your cherry trees early in the summer months, during the growing season when it is easier to identify cankers. Then apply a copper spray before it flowers. 

Crown Gall 

This cherry tree disease can produce galls that may appear too little to see with your naked eye, or they can produce galls that are as big as four inches across. Galls look like fleshy, white swellings that quickly grow and turn brown or tan in color. This is an infection that develops when your plant gets wounded, and cherry trees with alkaline, poorly-drained soils are more susceptible. If new galls form, they’ll usually show up right around the current ones. 

Unfortunately, managing this cherry tree disease with chemicals is ineffective. You’ll need bacterial biological control, but this is only available for commercial operations. To prevent it, make sure you plant in well-draining soil, and you want to plant disease-free, certified trees. Using good sanitation practices and rotating infected fields is also good. 

Cherry tree diseases come in several forms, but cankers are one of the easiest to spot.

X-Disease 

This cherry tree disease causes slow or quick decline of your tree. You’ll notice that your tree takes on a red hue on the bark and leaves, and the fruit can have incomplete color. It’ll also mature far later, and the limbs will eventually go through dieback before it kills the tree. An aggressive bacteria causes it, and cherry leafhoppers help spread it around. 

The best thing you can do for this is to get rid of any infected trees as soon as you notice it taking hold. Also, get rid of any plant sources that could contain the bacteria like chokeberries. 

Cherry Tree Diseases – Fungal Origins 

Fungal infections are the main causes of cherry tree diseases, and there are several different infections that can wreak havoc. They can spread to other trees in the area, and they can quickly take over and kill the tree. The fungus can overwinter on the ground on infected leaves and infected twigs, where you can see light brown swellings. Remove any fallen leaves regularly to help reduce the spread of the common cherry tree diseases.

Black Knot 

Black Knot is a cherry tree disease that attacks new shoots after heavy rains, and they take over very quickly in the second year. This forms elongated swellings on the tree’s woody parts, and these swellings can reach up to 12 inches long. The knots have a corky texture and look olive green at first, but this quickly changes to black and gets brittle and hard. The knots continue to grow each year. 

To manage this cherry tree disease, prune any knots on the tree’s branches and twigs, starting three to four inches below the swelling. Remove these pruned branches, and take them out of the orchard. On older branches, remove the knots and 0.8 inches of the surrounding branch. Midsummer is the best time to remove them, and fungicides work for treatment. 

If you don’t remove the diseased branches after you prune them, the infection can spread to healthy trees. 

Brown Rot (Fungal Disease)

Brown rot is a more common cherry tree disease especially with trees with sweet cherries that causes fruit rot, where the fruit will turn brown and wrinkle. With brown rot, the blooms will collapse, and you will see sap flowing from the bases of the flowers. The tree will form cankers with very dark edges on the twigs, and you may see gray-brown spore masses. The fungus will survive on the mummified fruit or sweet cherry, in the cankers, and in the blossoms, especially in wet weather. 

There isn’t a treatment for brown rot that is very effective, but the most effective brown rot control method involves applying protective fungicides. You want to time your application so the blooms are exposed after it rains. Avoiding watering with sprinklers can help prevent the blooms getting wet. Remove any mummified fruit, reduce stress, and remove infected twigs to alleviate brown rot. 

This disease is more common in trees with sweet cherries than those with sour cherries.

Cherry Leaf Spot 

This cherry tree disease (leaf spot) forms reddish purple spots on the leaves’ upper surfaces before the leaves turn brown. The leaves can become chlorotic due to leaf spot if there are lesions present, and the cherries can fail to develop if the cherry tree disease leaf spot progresses to severe levels. High humidity levels and warmer temperatures promote cherry leaf spot, and the fungus can survive wintering on the ground on infected leaves. 

You can control the spread by applying the correct fungicides. Unfortunately, this is a wide-spread problem with cherry trees, but there are some species that are more resistant to developing it than others. 

Crown and Root Rot

If you have this cherry tree disease, you’ll notice chlorotic leaves, poor growth, small stature, and the fruit may be brightly colored, small, and easy to sunburn. The shoots can dieback, and the tree can die within weeks of the first onset. If the tree is resistant to it, it can take several growing seasons to kill the tree. Your plant will show decay signs that turn into a canker. The infected portions turn dark brown, and water-saturated soil promotes it. 

Good water management is key to keeping this cherry tree disease away. You should have well-draining soil and reduce the amount and time you water. You want to apply fungicides as a preventative measure, and use resistant tree rootstock. 

Any type of rot will eventually make it to the fruit portion of the tree and cause it to wither. 

Powdery Mildew

If your tree has powdery mildew, this cherry tree disease forms circular lesions that have a light coloring on the leaves inside the tree’s canopy. If the powdery mildew infection progresses and gets more severe, the leaves may start to blister and any shoots that get infected can be stunted and distorted. The fruit develops depressed areas that house the fungi. If it rains close to harvest time, your plant is more likely to develop it. 

There are a few things you can do to help your plant survive this cherry tree disease. You want to apply the correct fungicides. Another thing you can do is ensure good air circulation when the humidity levels drop. This is particularly important around the canopies. 

Rust 

Rust is a cherry tree disease that forms pale yellow spots on your leaf’s upper and lower surfaces. The spots have an angular look, and they’ll eventually develop red-orange spores as it progresses. The fungus will eventually overwhelm your tree’s leaves and twigs, but it won’t cause them to fall off the tree. Instead, it’ll spread. 

You want to spray your trees with a preventative fungicide one, two, or three months before you harvest your fruit. This can help prevent early-season outbreaks that will carry on into late season outbreaks. 

Silver Leaf 

If your tree’s leaves turn a silvery hue and eventually curl upwards before becoming necrotic, you most likely have this common cherry tree disease. The entire tree of certain limbs can die, and you’ll notice fungal bodies appear on the dead bark. During days with high humidity and rainfall, the fungi releases spores that enter via pruning wounds. Trees that have heavy pruning are more at risk, as are trees that get pruned in the winter. 

It’s very difficult to control this cherry tree disease once it takes hold, and it can spread very fast after a rainfall if the fungus is already there. You want to remove any debris from pruning from the orchard. Also, start pruning during dry weather and treat any wounds you inflict when you prune with a fungicidal dressing. 

As the disease progresses, the leaves will take on a whiter appearance. 

Verticillium Wilt 

More spurs and withering leaves are hallmark signs of this cherry tree disease. The leaves will be stunted and look very dull. Your fruit will be very small, and your older cherry trees won’t be able to recover. In areas with wet soils, the cherry tree disease is more prevalent. 

To help prevent this from forming, you want to keep your cherry tree watered and fertilized during the growing season. Additionally, it’s a good idea to plant the trees in soil that has no history of previous disease. This can be difficult in some climates. 

Cherry Tree Diseases – Viral Origins 

Viral cherry tree diseases are less common than bacterial or fungal ones. However, they do happen, and they can have severe consequences if you don’t treat them quickly. 

Cherry Rasp Leaf 

This cherry tree disease will allow for leaf-like growths to slowly appear on the underside of the leaves. This viral infection starts at the lower portion and spreads upwards. Over time, the tree’s limbs will decay and the plant will eventually decline and die. Nematodes spread the infection by getting into grafted areas.

It can be challenging to control this cherry tree disease, but the best thing you can do is apply a fungicide that will keep the nematodes at bay. There is no cure for this infection, but you can control the spread and how fast it takes over. 

Sour Cherry Yellows 

Sour Cherry Yellows is a cherry tree disease that forms mottled patterns or chlorotic rings on your tree’s leaves. Eventually, the leaves become necrotic and drop off. This gives the tree a shot hole look, and the virus can appear years later and take the fruit yield down by as much as 50%. The leaves will turn yellow very fast as the disease progresses, and this infection can cause the tree’s death. 

There is nothing you can do to help it survive this infection. The best practice to prevent it is to purchase disease-free, certified trees. 

A decrease in the fruit yields are indications that the disease spread far into the tree. 

Cherry Tree Diseases – Pest Origins

Pests are a huge problem with cherry trees. They can lead to the spread of the diseases, but they can also wreak havoc by themselves. Fortunately, it’s easier to prevent, control, and get rid of a pest infestation than it is a bacterial, fungal, or viral one. 

Aphids 

Aphids are soft-bodied, small insects that live on the underside of the tree’s leaves. They are black with a shiny coloring, and they can cause the leaves to distort and turn yellow. They form necrotic spots on the leaves, and they can cause the shoots to become stunted. They secrete a sticky substance that encourages mold growth on your tree. They overwinter on the trees before hatching in the summer to feed. 

You want to remove any mustard volunteers that are growing around because these attract black cherry aphids. You can spray the trees with a strong jet of water to dislodge the bugs, and you shouldn’t have to use an insecticide unless you have a severe infestation. Neem and canola oil can help, and it’s best to treat them when the plant goes dormant for the winter. At petal fall, reapply your horticultural oil or insecticide. 

Peach Twig Borer 

The Peach Twig Borer will cause damage to the fruit and shoot tip death. The larvae of this pest are dark brown with white patches and a black head. The adults turn into moths with a grey-brown coloring. They overwinter as larvae in the tree’s bark before emerging to feed in the early spring and summer months. 

The best treatment method for this pest is applying insecticide around the time your tree blooms. Ideally, you’ll use organically-friendly insecticides that won’t burn your tree. 

Spider Mites 

This is a very common pest that makes the leaves look bronze or yellow and stippled. They leave a webbing on the leaves, and you’ll see these mites on the underside of the leaves as tiny brown dots. You won’t normally spot this pest until your plant has a large problem like the leaves turning yellow and falling. They do very well in dusty environments, and trees that are stressed are more susceptible to an infestation. 

Spraying with a strong water jet can help knock the mites off the underside of the leaves, and it can cut down on the population in general. If they develop into a large problem, get an insecticidal soap and spray the surfaces of the leaves. Specific chemical-based insecticides can increase the mite population because it’ll kill off the predatory bugs that eat the mites. 

It’s easier to see spider mites if you use a magnifying glass. 

Western Cherry Fruit Fly 

This pest causes your fruit to turn mushy because a single maggot will eat it from the inside out. The adult version of this pest is a fly that has white bands on its abdomen, black body, and a dark pattern on the wings. They can be extremely damaging in the western areas of the United States. If the infestation gets out of control, every single fruit can have a maggot. 

Yellow sticky traps can help cut down on the pest population, and you want to use an ammonium carbonate lure. You want to target egg-laying females with your chemical insecticides. Even if you don’t have an infestation, you can pre-treat your trees to stop them from taking hold. 

Healthy cherry trees will continue to thrive for years to come with care and patience.

Cherry tree diseases can wreak havoc on your cherry trees, and they can lead to death. Fortunately, there are several ways to prevent and treat a lot of them so you can save your trees. Prevention is much better than treatment, so keep an eye out and keep your trees healthy.