There are fewer trees on the golf courses this year, making play somewhat easier for me. The reason for the decline: Kansas has no native pine trees. They are all immigrants, and because of this, they suffer more than most trees from bugs, fungi and weather-related problems.
Various species were brought here for windbreaks, Christmas tree farms and landscapes. Periods of drought, high temperatures and now the spread of insects and diseases are affecting their very existence. There are eight specific issues for pines in Kansas - not to mention that they are not drought-tolerant and do not like our winters. Four of these issues are prevalent this time of year.
- The first issue is a natural event called needle drop. This affects pine, arborvitae and spruce. Simply put, the plant is shedding its leaves (needles). The inner needles on a stem turn yellow and drop, leaving the outer portions green and healthy. This yearly drop will start on trees 2-4 years old and benefits the plant.
- Next, there's brown spot, which is a fungus that affects the ponderosa, and Scots pine (also called Scotch pine). The Austrian pine is resistant to brown spot. Lower-limbed needles develop yellow-to-tan, resin-soaked spots. The spots may enlarge to band the needle completely. By mid-fall, diseased needles turn completely brown and fall from the tree. The fungus overwinters in the diseased needles. New spores are dispersed with the spring rains. A good indicator of brown spot is the spread from the bottom of the tree up. One or two applications of a fungicide in May or June and again three to four weeks later may deter further development in the infected tree, but is more effective in preventing the spread to adjacent trees. Removing and destroying the infected needles, both on and under the tree, is recommended.
- A similar fungus, Dothistroma needle blight, affects Austrian, ponderosa and mugo pines. Like brown spot, it affects the lower portion of the tree. Symptoms are dark green bands or scattered yellow-to-tan spots on the needles. The band or spot will turn red, the needle past the band will turn brown, and the base of the needle will remain green. Two fungicide applications, mid-May and mid-to-late June, are recommended, especially on adjacent susceptible plants. Make sure that all needles are covered completely with the fungicide. Removing and destroying the infected needles is again recommended.
- Pine wilt is the most serious problem for Scots pines in Kansas. It also has been reported on Austrian and more rarely on eastern white pines. It is caused by a very heavy infestation of a microscopic worm called the pinewood nematode.
The fatal problem was discovered for the first time in the United States in 1979 in Columbia, Mo. It was found the same year in southeast Kansas and has been progressing west at about 10 miles per year. It is now just west of Hutchinson.
The pinewood nematode population explodes during hot Kansas summers, severely reducing the tree's resin and moisture flow. This reduced flow dries and then kills the needles and soon the tree itself. The symptoms appear well after the tree is infected. The stressed tree can die in a matter of weeks.
Here is the interesting part: The nematode is a small worm and has no method of getting around. Nature has provided another insect, the pine sawyer beetle, to be the nematodes' transportation. The beetles lay their eggs on recently cut or fallen pine logs and overwinter on the infected wood. The adult sawyer emerges in the spring and, just as they do, the nematodes (numbering in the tens of thousands) enter the sawyer beetles' windpipe ready to travel. The pine sawyer beetle searches for a new tree, depositing nematodes as it feeds, and the cycle begins anew.
Pine wilt has no cure. Prevention may be possible by using one of two chemicals, Aracinate or Greyhound. They must be applied by a certified applicator (usually arborists) and are very expensive. A single application may cost $150-$300 per tree plus labor. They are 40 percent to 80 percent effective. Sanitation is the only way to stop the cycle. Remove and destroy all infected wood, every year, before the beetles start to emerge in April and May.
These are just the fall concerns. In the spring, the European pine sawfly affects Scots and mugo pines; Sphaeropsis tip blight affects Scots, mugo, Austrian and ponderosa pine; Pine needle scale affects pine, spruce, fir, hemlock, yew, and cedar; and the Nantucket pine tip moth affects Scots, Austrian and mugo pine.
I certainly can understand why the pine tree has not naturalized or done well at all in Kansas. Still, we try, and the lone survivor at the golf course still catches many of my golf balls.