Keeping your trees healthy is important, and there are six common tree diseases you should be aware of. Some of them are fungi, some are insects, and others are weather related. The good news is that you can usually treat them.


During cool, wet spring weather, trees can be susceptible to the tree disease Anthracnose. This disease causes small, irregular dead spots to appear on the leaves and stems. Infection is commonly associated with poor soil conditions, including restricted drainage.

Infected leaves may form spores that will spread to new growth. Some spores may germinate on new growth, while others may remain on the infected leaf. Typically, the spores appear on the underside of the leaves and may cause leaf damage. In severe cases, spores can form a film of water on the leaf surface.

During outbreaks, Anthracnose can cause twig and branch dieback, as well as fruit damage. Fruit may develop dark spots, and in severe cases, fruit may rot completely.

The best way to prevent anthracnose is to prevent infection in the first place. The disease can spread from tree to tree through wind, rain, and insects. It’s also a good idea to hire a professional to evaluate your tree for disease. They can help you identify the symptoms, treat the tree, and provide preventive treatments.

Anthracnose may be particularly severe on the lower branches of trees. Infected branches may become twisted, have swollen edges, or sink down. In addition to causing defoliation, the twisted appearance and swollen edges can lead to girdling, which destroys nutrient conducting tissues.

Infected leaves can also become cupped, curled, or distorted. In some cases, the affected leaves will be completely wilted.

The disease can be prevented by maintaining healthy soil conditions and pruning out infected branches. Proper pruning practices will also increase air circulation, helping the leaves to dry faster.

The disease is also highly susceptible to rainy weather, which can favor the spread of the disease. If you suspect anthracnose, it is important to take action immediately to prevent further damage to the tree.

Leaf rust

Various rust diseases have been identified in many different plants. They may affect leaves, stems, branches, flowers, and fruits. Rust fungi can infect a variety of plants, but the ones most commonly infected are those of the genus Pinus.

Rust fungi are obligate parasites that require a living host plant. They infect plants by the process of spore production and germination. The spores are windborne and spread by wind and rain. They can also infect other plants that share the same host.

The rust spores germinate on a wet leaf and grow mycelium. They then produce urediniospores. Uredospores are light and require water for germination. Eventually, the spores re-infect the same host. If the spores are left on the plant, they can cause a massive infection.

Symptoms of rust include yellow, brown, orange, or red spots on leaves. These spots will turn darker over time. Rust can be treated by spraying fungicides.

Rust can also cause stunted growth and yellowing of leaves. If left untreated, rust can cause the leaves to die off. Rust also causes blisters on the leaves and cankers on the branches. If you are growing a plant with rust, you may have to cut the plants down to ground level to prevent the disease from spreading.

Rust is not a common disease on native Eucalyptus trees. However, it is not unknown on exotic Pinus spp. There are several species of tree rust, and they all have a different life cycle. Some go through five stages on a single host while others infect only one plant species.

Rust on leaves can be treated with neem oil. Neem oil sprays are commercially available and can be applied to affected leaves. You can also use mild liquid soap to spray the affected area.

Powdery mildew

Whether you’re growing plants indoors or outdoors, powdery mildew can be a hazard. Although it is not fatal to plants, it can cause debilitating blight. Luckily, there are some effective ways to control the disease.

First, a fungicide spray is recommended. Some products, such as Bonide Liquid Copper Fungicide, hook up to a hose and are ready-to-use. Another fungicide that’s effective is sulfur. These are typically the least expensive, but need to be applied preventively.

In addition to fungicide spraying, removing dead foliage and pruning the plant are important steps to prevent powdery mildew. When you plant new plants, avoid planting them in crowded areas. Also, make sure that your planting location has enough drainage. Aside from preventing the growth of fungi, proper plant spacing can reduce humidity and increase the amount of light available to the plant.

Adding a compost to the soil can also help boost nutrient levels. This can also increase the number of beneficial microorganisms in the soil. These organisms may help boost the plant’s immunity.

You should use a fungicide to control the disease, but make sure that you do it according to the instructions on the label. The best time to apply a fungicide is in the early stages of infection. It is also important to read the instructions before you start treating a large area. It’s also a good idea to pretest a fungicide to ensure that it won’t hurt the plants.

One good way to control the disease is to apply a milk and water mixture. It’s made by combining one part milk with nine parts water. It’s applied to the plants in the morning or evening. You should repeat this procedure once every two weeks to keep powdery mildew at bay.

Verticillium wilt

Symptoms of Verticillium wilt include stunted growth, yellowed foliage, foliar chlorosis, marginal leaf scorch, premature defoliation, and branch dieback. Although this disease is widespread and causes damage to many different plants, it is not fatal. The symptoms usually appear late in the growing season.

Verticillium wilt is most prevalent in regions with warm, sunny weather. It is also a problem in irrigated areas. Plants that are susceptible to verticillium wilt should be properly watered and fertilized.

Verticillium wilt can infect a wide variety of woody plants, including maple, elm, redbud, catalpa, oak, and lilac. The disease is most common in southern New England.

Verticillium wilt causes branches to die suddenly and abnormally. It can kill small trees in one season, but larger trees may take years to die.

The fungus enters the plant through wounds in the root system. It plugs water-conducting vessels and sap pathways, causing the wilting and dieback of the tree. The disease usually affects the branches on one side of the tree.

The disease is caused by two species: Verticillium dahliae and Verticillium albo-atrum. Both fungi infect plants by entering the root system and residing as microsclerotia. Some species of verticillium wilt are more virulent than others.

Verticillium wilt cannot be cured. However, the disease can be controlled by pruning infected branches. Properly pruning branches that are diseased will prevent the fungus from spreading and will also help maintain the aesthetic value of the tree. Tree services Sunshine Coast offered by Elite Tree Company can help you control the damage and extent of this disease.

Verticillium wilt occurs primarily in ornamental plantings. If you suspect that your plant has verticillium wilt, ask your arborist to test it. You can also check the University of California’s leaflet “Plants Resist and Susceptible to Verticillium Wilt”.

It is important to avoid planting susceptible plants in the same area. A verticillium-resistant tree may be the only viable option.

Elm bark beetle

During the spring and fall, an elm bark beetle can cause an elm tree to become infected. There are two species of bark beetles that carry the fungi which cause Dutch elm disease. The American elm bark beetle is less common than the European elm bark beetle. Both species can cause fungi to spread from tree to tree.

The native elm bark beetle, Hylurgopinus rufipes, is a common pest in Wisconsin, Minnesota, and northern Minnesota. It can tolerate cold winters in the prairie regions of North America. This species breeds in dead elm wood and firewood. The larvae feed in the twig crotches of the elm tree and carry the fungus to the new host.

European elm bark beetles are more common in other parts of North America. They lay eggs on dead elms and lay their spores on the inner bark. The spores are then carried by bark beetles to the next host.

The fungus grows within the vascular system of the tree and spreads through the sapstream. It can spread up to 15 metres from a healthy tree. The disease is most likely to affect trees that are stressed or weak. The tree is most susceptible to infection after the first leaves have unfurled in the summer.

The females bore tunnels into the inner bark and lay small oval whitish eggs. The spores are carried by the females and the bark beetles. They reproduce through yeastlike budding.

The bark beetle larvae feed by making galleries which are perpendicular to the female’s gallery. The larval mines gradually increase in diameter as the larvae grow. The pupation takes place in enlarged chambers at the end of the larval tunnels.