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Diseases of Pine Trees

pine cone on a pine tree image by MAXFX from

Pine trees are softwood trees that make excellent screens or windbreaks because they grow in compact groupings. According to Tree, there are roughly 35 different pine tree species in North America, with most of them in northern regions. The right diagnosis is important because a tree can die if diagnosed and treated incorrectly. Gardeners should note common signs of diseases such as white resin, defoliation, holes in trunks, needle discoloration, and cottony growth on bark.

Annosus Root and Butt Rot

Annosus root and butt rot affects all southern pine trees, but particularly Loblolly and slash pines. It usually occurs around cut tree stumps. Signs of the disease are thinning foliage in a tree’s crown area and red needles appearing on dead trees. This disease eventually kills trees. Any dead or infected trees must be removed to prevent the disease from spreading to other trees. According to the North Carolina State University Extension website, another pine should not be planted within 20 feet of an infected tree.

Fusiform Rust

Fusiform rust is a disease involving swollen elongated galls, which are abnormal outgrowths on branches or trunks. An infected tree can become stunted in growth or even die. Whenever a gall occurs on the main trunk of a young tree, the tree should be cut down and removed. Galls on branches that are 8 to 12 inches from the trunk just need pruning, as there’s little chance the rust will reach the trunk, according to the North Carolina State University Plant Pathology Extension website.

Dothistroma Needle Blight

Dothistroma needle blight, also called Dorthistroma needlecast, is a disease that only affects pine needles and is caused by the fungus Dothistoroma pini. Both young and old pine trees can contract this disease. Although it can attack any species, the most vulnerable pine trees are ponderosa, Austrian and mugho pines. Signs of the disease are needles that shed prematurely, or needles developing tan or yellow spots which change to red or brownish bands. Although the needle base stays green, needles from the outward bands die.

Blister Rust

Blister rust is a disease in which branches and trunks of pine trees become slightly swollen. White blisters containing yellow to orange spore masses are seen in early summer are sign of blister rust. This pine disease occurs in mountains and high elevations. It’s capable of killing individual branches or an entire tree when occurring in the lower crown of tree trunks.

Pitch Canker

Pitch canker is a serious pine tree disease that’s a fungus transmitted by twig beetles on bark and pine-cones. Symptoms of the disease include branch tips that turn brown, wilting and resin that exudes from the area of infection. This disease causes branches to die and trunk infections that can even kill a tree. There’s no know control for pitch canker, but pruning infected branches helps prevent the fungus from traveling to the trunk.

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