Multiple diseases taking toll on Kansas pines

ORIGINALLY WRITTEN JERRY ENGLER
Kansas pine trees, the brightest year-around evergreen we have, are dying.


Rod Franzen has been watching the pine trees sicken, with needles turning brown and dying, from southwest of Hillsboro to Goessel to Hesston for more than a year.


Franzen has one dead Austrian pine to be cut down in his own yard, and he sees especially the Scots-formerly often called Scotch-pines sick or dying at many neighbors’ homes, “like watching a horror story.”


He’s noticed hurt or dead pine trees at many neighbors, including Ron Hiebert’s, Alexanderwohl Church, Mark Jenkin’s, Harold Unruh’s, Myron Schmidt’s and more on his way to work at Hay and Forage in Hesston.


Franzen heard a radio discussion on disease spread by birds, and about pine tree losses in McPherson, Moundridge and Lindsborg. He said he wonders about the economic impact of losing pine trees in windbreaks helping conserve soils and utility costs, in Christmas tree plantations where the Scots pine is a mainstay, and in thousands of home lawns where pine trees help improve home values.


Joyce Unruh confirmed that Scots and Austrian pines she and her husband, Harold, have on their home place and a neighboring place seem to be in trouble. With the “monster-size” Austrian pines in a 30-year-old windbreak, she said it appears to be a slow process.


“There’s not a lot of them going at one time,” she said. “They just seem to turn brown gradually, and after a while that tree’s gone.


“With the Scots pines there seem to be three or four of them in a row that will all of a sudden be gone. We’ll have a couple of the Austrian pines in the yard turn brown every year.


“Now in places where other trees shade them, maybe they just don’t get enough light, or maybe it’s because of the drought. It’s too bad. They’re nice trees, and something’s happening.”


Ned Tisserat, plant pathologist at Kansas State University, said local residents are right-something is happening to the pine trees, and it’s complex because several diseases are involved.


As a matter of fact, the situation is so bad that trees like the Scots pine, Austrian pine and Ponderosa pine, once considered beautiful alternatives for Kansans, may no longer be recommended for Kansas at all, he said.


Although some have expressed interest in bringing in the Pinyon pine, Tisserat said Kansans may even have to accept a tip from nature, and plant native Eastern red cedar trees for evergreens.


Ponderosa pines and Austrian pines can still be used, but avoid planting too many, he said.


“Certainly back off of Scots pines; they are rapidly dying in Kansas,” he said.


Tisserat said even though some spruce trees look beautiful, he

doesn’t recommend turning to any spruce varieties for evergreens in Kansas because they are too susceptible to drought injury.


“It really is tough to recommend a good evergreen for Kansas,” he said.


Lloyd Schroeder, who has a Christmas tree business at his Pine Creek Farms near Goessel, said his plantations of Scots and Austrian pines remain disease-free, but only because of a vigorous spraying program. Schroeder continually sprays with insecticide, concentrating on the Scots pines, and with fungicide, concentrating on the Austrian pines.


The Schroeders are members of the Kansas Christmas Tree Association, and attend meetings twice a year to find out what’s going on in tree care.


“It’s like anytime you raise anything, anytime you have a concentration, that’s when you have problems,” he said. “They’ve always told us that anytime you have a tree that’s looking a little different, like it might have something, to cut it out and burn it, and we’ve always done that.”


Schroeder has some older, mature trees too, and hits them periodically with spray when he’s working anyway. He noted that the mature trees seem more susceptible to disease than young trees.


Tisserat said pine wilt, a disease mostly of Scots pines, is caused by a nematode, a microscopic worm, although several more organisms are involved. Three other fungus diseases are also causing damage: sphaeropsis tip blight mostly on Austrian, Ponderosa, Scots and Mugo pines; dothistroma needle blight mostly on Austrian, ponderosa and Mugo pines with Scots pines being resistant; and brown spot disease mostly on Scots pine Christmas tree plantations.


“To confuse matters a little more,” Tisserat said, “there are pines that are simply drought injured.”


Tisserat said the nematodes causing pine wilt usually come into a Scots pine to feed on blue-stain fungi and also the living plant cells surrounding the resin canals, which are the water-conducting passages of pines. The pine needles turn gray-green, then tan and brown as the tree declines within a few weeks to a few months.


Tisserat said the nematodes are unable to move to new trees without the pine sawyer beetle. The strong-flying female beetles fly to new trees laying their eggs under the bark of dead or dying trees.


Tisserat said when their grubs hatch they feed, and then tunnel deep into the wood. When the adult sawyer beetle breaks out of its pupal shell, pinewood nematode larvae move into its breathing tubes, so each beetle carries up to tens of thousands of hitch-hiking nematodes.


The beetles feed on twigs of healthy pine trees, causing wounds or points of entry for the nematodes to enter the healthy trees, probably in response to chemical cues from the injured twig, Tisserat said.


As the pine begins to die, it attracts not only more sawyer beetles, but also bark beetles, which carry blue-stain fungi to colonize the tree, therefore providing more food for the nematodes.


Drought and high temperatures stress pines to lower resistance, and also help the nematode reproduce faster, Tisserat said.


News reports indicate the nematode, a native of the United States, is causing the same problems in neighboring Midwest states and in Japan, where it has caused widespread losses in forested areas.


Tiny brown or black fungus fruiting bodies on stunted needles or pine cones are indicators of the fungus diseases, Tisserat said.


Tip blight is most severe on 30-year-old or older Austrian pines causing the death of new shoots in May or June with repeated infections over several years killing large branches or the whole tree.


Tisserat said this disease can be controlled with a fungicide like bordeaux, usually about the third week in April depending on whether the new shoots are elongating, and again 10 to 14 days later.


Dosthistroma needle blight causes premature dropping of pine needles the year following infection, and because Austrian and Ponderosa pines retain needles for three or four years, the premature loss of needles results in reduced photosynthesis and a decline in tree vigor that may kill the tree, Tisserat said.


Needle blight symptoms appear in late summer or early fall with diseased needles showing dark green bands, or scattered yellow to tan spots, that may enlarge to red bands bordered by light yellow regions. Two applications of fungicide, one in mid-May and one in mid to late June, may control the disease, he said.


Brown spot resembles the needle blight both in needle drop and appearance, but it is the Scots pine that is susceptible to it, Tisserat said.


The same two fungicide treatments can be given for it, and people should avoid planting short-needled Scots pines that originated in France and Spain, and plant long-needled varieties for resistance, he said.


Anyone wanting to send a wood sample to K-State for analysis should use a brace and bit to remove a disk of wood one inch thick and three to four inches across without bark chips.


Samples should be sent to the Plant Disease Clinic, Throckmorton Plant Science Complex, Kansas State University, Manhattan, KS 66506, or contact a county extension agent for help.

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