Pine Tree Disease

Pine trees are susceptible to many diseases.

Pine tree diseases can cause devastation when they aren't diagnosed promptly. The proper diagnosis and treatment can mean the difference between a tree that will recover, and one that needs to be permanently removed from the landscape. If your pine tree is looking anything less than spectacular this year, consider if any of the following diseases may be infecting your stand of trees.

Diplodia Blight

Diplodia blight of pines is a treatable condition if discovered early. This pine tree disease is characterized by stunted, brown new growth in the spring, resin drops forming on the stunted growth and entire branches that have died. The source of this disease is a fungus that spreads quickly in the spring, Diplodia pinea. It usually infects single plantings in landscaped yards, parks and trees used in windbreaks. It seldom affects pine tree stands in the wild. Trees can become infected after pruning, from holes made in the tree by boring insects and from wind or hail damage.

The treatment for diplodia blight is two applications of fungicide when the tree begins budding in the spring. The applications of the fungicide should be at least one week apart. Avoid pruning the tree during this period as the fungus can infect any open wounds.

Armillaria Root Disease

Armillaria root disease is caused by the Armillaria fungus and is known by many names. Some of the more common names include mushroom root rot and toadstool disease. This is because mushrooms and toadstools are found at the base of the tree once the infection is established. It is difficult to diagnose this disease at the onset because it attacks the roots underground. However, once this fungal disease begins spreading, the outward appearance of the tree will change. Characteristics of the disease include the thinning of foliage, trees turning completely yellow then brown before dying, and stems producing copious quantities of resin. Douglas Firs in particular will produce an unusually large crop of pine cones before they die.

Treatment for this disease is the application of fungicide at the base and around the roots of the tree and where there are any open wounds. Trees that cannot be saved must be uprooted and destroyed. New pines should not be planted in an area where an infected tree has been removed.

Annosus Root and Butt Rot

Annosus Root and Butt Rot is a disease spread by the fungus, Fomes annosus. It is primarily spread when tree stands are thinned. The fungus enters through the cut tree stumps and then spreads underground to healthy living tree roots nearby. Conks found at the base of the tree characterize this disease. The conks are hard and leathery, and are light brown on the top and a cream color underneath. Other characteristics of the disease include thinning of the foliage, slowed growth and weakened trees toppling over.

The treatment of this disease includes treating tree stumps after cutting with borax and by spraying the base of infected trees with fungicide. The fungus can survive in an untreated tree stump for decades.

White Pine Blister Rust

White Pine Blister Rust affects the Eastern White Pine. The fungus, Cronartium ribicola, causes the disease. The fungus has five stages, two of which are completed in the pine and three are completed in nearby host plants. The host plants are often currants and gooseberries. The disease is characterized by branch infections, beginning in the needles in the first year. In the second year, a diseased trunk becomes a dark yellow to orange color. Infected areas on the stems will also become discolored, forming blisters. The blisters will then burst, releasing more of the fungus spores. In succeeding years, the scars from these blisters will form new white blisters in the spring. When these blisters burst, they will release orange spores, which will then spread to currant and gooseberry plants in the area. These spores can be found infecting the underside of the leaves on the new host plants.

If treated early, the tree may have a chance at survival. Treatment methods for this disease include branch pruning to completely remove blistered branches, removal of all lower branches and excising of cankers, including five centimeters of live tissue surrounding the canker.

Diagnosing Pine Tree Diseases

With some diseases, it is difficult to diagnose the problem, especially at the onset when the disease may be starting underground. Once you have noticed that your pine tree is not thriving or is losing a large portion of foliage, call an expert to assist in the diagnosis.

A Cooperative Extension agent is a good source of information and in many cases will visit the infected tree to make a correct diagnosis. Alternatively, speaking with a representative of the nursery from where you purchased your tree can also narrow down the cause of the problem.

After the problem has been diagnosed, a treatment program can begin. In the end you'll have a better understanding of how to treat your pine trees for these diseases, as well as how to prevent them in the future.

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Pine Tree Disease