|
|
|
|
|
|
 |
|
|
|
Over the past decade, pine trees have become
a popular addition to rural and urban landscapes. Recently, however, a
disease called pine wilt has killed many mature Scotch pine species in
southeast Nebraska. Pine wilt is caused by the pinewood nematode, a
microscopic (1 mm) long, worm-like animal, which is moved from infested to
non-infested pine trees by the pine sawyer beetle. Pine wilt typically kills Scotch pine within a few weeks to a few months after the pine sawyer beetle introduces the nematode to the tree. Needles usually turn grayish green, then tan, then brown and may remain dead on the tree for a year or more. Scattered branches of the crown may be affected initially, but the symptoms soon spread to the remaining branches. Entire trees may turn brown all at once. In addition to Scotch pine, the disease occasionally appears in Austrian, Jack, and Mugo pines and, though rarely, also in White pines. Ponderosa pine does not seem to be susceptible to pine wilt. As pines age, they become more vulnerable to the disease, which almost always has appeared in trees over 10 years old. Since no chemicals are available to control the nematode or beetle, sanitation is the most important practice to prevent or slow the spread of pine wilt. To limit the spread of pine wilt to nearby healthy trees, diseased trees must be removed and destroyed before the beetles emerge from the wood. Between May 1 and October 1, dead and dying pines should be cut down promptly and burned, buried, or chipped. Do not hold the wood for firewood. The pine beetle is not active from October to May, so dead trees found during this time period do not require immediate removal but should be destroyed before May 1. |
 |
|
|
