Archive for Thursday, January 15, 2009

Pine disease prevents species from thriving in Kansas

January 15, 2009

Today we start a two-part series about one of the most popular trees in Kansas, the pine tree, and some of the disease problems pines face.

Pines are a favorite part of most landscaping projects because of their evergreen qualities, but unfortunately, some pines around here are not very green anymore. It seems pines all too often fall victim to the many diseases and environmental hardships our midwestern climate poses.

An interesting piece of information about pines is that they are not native to Kansas; in fact, Kansas is the only state among the 50 states in the union that does not have a single native pine species. The reasons for this may become more obvious as I highlight the two major pine diseases — tip blight and pine wilt — we see here in the Midwest, as well as several environmental problems pines face.

I will dedicate today’s article to discussion of the pine disease tip blight. Tip blight affects Austrian, Ponderosa, Scots and Mugo pines. Usually it’s most severe on trees more than 20 years old, and can be lethal to pine trees over time. The symptoms first occur in late May or early June. Tip blight keeps the new shoots (candles) from growing and elongating and causes them to eventually turn brown. The needles at the end of the branches will be brown and have a stubby appearance. The disease can also spread to a tree’s old wood, where it will form a canker (a physical wound of the trunk or limb). Fungal cankers are known to kill entire branches and sections of trees.

Besides looking at the tree’s new growth, or lack thereof, you can also see symptoms of tip blight by looking for black specks on the bottom side of 2-year old pine cones. These black specks are the pycnidia, or the spore producing stages of the disease, and become visible during the late summer months.

Removal of infected branches is one way to control the disease but once a tree has the infection, you cannot truly get rid of it. If a tree has tip blight, the best way to prolong the health of the tree is to maintain its vigor. The best way to do this is to adequately supply water and nutrients to the tree.

Prevention is the best measure against this disease, and the use of fungicides is the best way to prevent infection. These fungicides need to be applied to the new growth as it is emerging in order to protect it from fungal infection. Most copper fungicides will work for this purpose and are available to homeowners.

Every year you will need to spray around the third week of April. Spray again 10-14 days after the initial treatment, and then again 10-14 days after the second treatment for maximum protection of new growth.

There are several other fungicides that work well in preventing tip blight, but they are mostly restricted-use chemicals that need to be applied by a professional tree-care service. A good reason to consider a professional would be that they will have the equipment necessary to adequately reach all parts of large, established trees (remember that tip blight normally affects trees more than 20 years old).

Keep in mind that next week’s article will focus on the other major pine disease, pine wilt, while also mentioning a few of the environmental stresses pines must endure.

If you have questions about pine trees or pine diseases, you can contact me at the Leavenworth County Extension Office on the corner of Hughes and Eisenhower roads in Leavenworth, or call (913) 250-2300. I can also be reached via email at mepler@ksu.edu.

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