Problems with pines

    I have been receiving many questions about pine trees.  In the past few weeks, I have seen a lot of dothistroma needle blight and some sphaeropsis tip blight.  
    Dothistroma needle blight is a common and serious disease of Austrian and Ponderosa pines.  Mugo pines can also be susceptible. This particular disease causes premature dropping of pine needles.  The tree was infected last year and is just now losing its needles. Premature loss of the foliage results in a reduced photosynthetic area and loss of tree vigor and if left over several years, it can kill the tree. The damage I have seen was actually caused last year and is just now starting to rear its ugly head.
    In late summer or early fall, diseased needles exhibit dark green bands or scattered yellow to tan spots.  These spots can become enlarged and develop into red bands that encircle the needle. The red bands can be bordered by a light yellow region The tip of the needle turns brown, but the needle base remains green.  Typically, the disease is the most severe in the lower portion of the tree crown.
    If you know your tree was infected last year, I would recommend a single fungicide application in early June to protect the foliage from further infection.  There is some risk in a single application, as older needles will not be protected early, but it is too late to apply two fungicide applications.  In most cases, yearly spraying will not be necessary once the disease is brought under control. Recommended treatments include copper fungicides such as Bordeaux Mixture.
    Sphaeropsis tip blight, also known as diplodia, is a fungal disease that affects Austrian, Ponderosa, Scots and mugo pines. This tip blight primarily causes the death of new shoot growth in the spring. Repeated infections over a period of years can result in serious damage to the tree.  In Kansas, sphaeropsis is mostly seen on mature pines and most generally in Austrian pines.
    The symptoms first appear in late May or early June. New developing shoots (candles) fail to elongate properly and turn yellow or tan. Small droplets of resin often form on the stunted needles.  Normally the infected needles remain attached on the branch, but lately our Kansas winds have helped to clean a few branches. Dead shoots are usually seen in the lower portion of the tree crown.
    It is very easy to confuse sphaeropsis tip blight with winter damage or that of the pine tip moth. This blight results in stunted, yellow to tan shoots, and black fruiting structures are visible on both needles and cones in the fall and winter.  I often tell people to look at the underside of the pinecone and if it looks as though someone got carried away with a pepper shaker, then it is probably diplodia.  
    Control of Sphaeropsis tip blight is aimed at protecting the susceptible shoots from the fungal infection in early spring. Tip blight can be controlled with two applications of an appropriate fungicide if the chemical is applied at the right time. Effective fungicides include Bordeaux Mixture, Fungo, or Cleary’s 3336. The time has passed on the window of treatment for this year.  
    Other options to help control these diseases include the removal of dead limbs, picking up infected pinecones, raking up and destroying fallen needles.  Trees attacked by tip blight should also be adequately watered and fertilized.  
    As with any chemical, be sure to read and follow label directions and for those with large trees, you may want to consider having the job professionally done.
    For more information on tip blights of pine or other tree diseases, visit us online at www.ford.ksu.edu.