Pine tip blight disease is caused by the fungus Diplodia pinea, formerly known as Sphaeropsis sapinea. Tip blight symptoms appear as new shoots (candles) are developing and elongating in spring. Infected needles and shoots stop growing and turn brown. The stunted and brown needles and shoots become very conspicuous in summer compared to healthy shoots. Tip blight disease usually starts on lower branches and works its way upward in well-established trees about 10 or 15 years old. As infection proceeds into older tissue, additional needles and branches are killed. The fungus produces tiny, black fruiting bodies (pycnidia), which may be observed with a hand lens, at the base of infected needles just under the needle sheath. In advanced cases, infected branches may develop resin-soaked cankers. In the tree and on the ground, old infected cone scales are peppered with pycnidia and are potential sources of fungal inoculum.
There are indications that the causal fungus already exists in a latent form in healthy-appearing trees and branches and only needs an opportunity to become pathogenic. Stressful growing conditions such as drought and shade favor tip blight disease in pines. Tip blight is especially damaging to Austrian and Scots pines, but can also infect white pine, red pine, Virginia pine, and even other conifers such as spruce.
To manage tip blight, prune out and destroy infected twigs, branches, and cones. Provide favorable growing conditions for the tree to reduce stress. Fungicide applications made in early spring at bud break and while candles are elongating may slow disease development.
Contact your local Extension office for fungicide recommendations.
