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Pine wilt hitting hard in Pratt

Gale Rose
Brown needles make pine wilt that has shown up in several trees early in June in Pratt County. While some needles are half green and half brown, some heavily-impacted trees are completely brown.

An annoying problem is showing up around Pratt. In a few locations, pine trees are showing signs of pine wilt, a disease that is fatal to specific pine trees.

While some needles are brown part way, a few trees are covered with totally brown needles from top to bottom.

Several years ago, the Pratt area was hit hard by pine wilt and many trees died. Pine wilt is a recurring problem with trees effected every year, said Chris Mullins, district forester for the Kansas State University Forest Service.

May and June is a typical time of year for pine wilt to show itself. It shows up on needle tips then moves up the needle until its entirely brown.

Pine wilt is caused by a microscopic nematode that burrows into the tree resin and interrupts the flow of resin necessary to provide oxygen to the tree. The nematodes are carried from tree to tree by the Sawyer beetle. The beetle makes a wound in the tree and the nematode makes its way in and injects a fungus into the three resin. If a tree gets pine wilt, it is a death sentence.

Mullins said the wet weather in 2019 provided the perfect conditions for pine wilt to thrive.

Scots pine, Scotch Pine and Austrian Pine are most susceptible to the disease, Mullins said.

Trees older than 10 years are more susceptible. If a tree gets too much moisture or not enough, it is more vulnerable to the disease. The Sawyer beetle is attracted to trees that are stressed from heat and drought.

If rainfall is limited, watering the trees helps keep them healthy and more resistant to the disease. If there is too much moisture, the roots can use up oxygen and die. If there is too much rain, the roots can rot.

Pine wilt is hard to diagnose in the early stages. As it progresses, it becomes more obvious.

Unfortunately, once a tree gets the disease, there is nothing to do. Trees can be sprayed but it is an expensive process and does not guarantee the tree won't get it.

Infections are most visible from August through December. Dead trees should be cut down no later than April 1, according to the Kansas Forest Service web site.

Every year, the forest service at KSU gets calls about pine wilt. This year, the forest service is getting a lot of calls from northeast Kansas around Hays about pine wilt.

If a tree is showing signs of pine wilt and there are other pine trees close by, there is a good chance they have it too.

Dead trees need to be cut down. If not, the beetles will migrate to other trees. The wood needs to be burned. Burning in place should be done if possible but if not, take the trees to a landfill where they can be burned there.

The Pratt parks system has three dead trees right now. They have not been able to remove the trees because workers are busy trying to keep up with watering, weeding and mowing the grass. They are also shorthanded because of the coronavirus, said Danny Quint, Parks Department supervisor.

Eventually, the dead trees will be cut down and hauled to the landfill to be burned.

Pine wilt has been around Pratt for at least 10 years and the city loses some trees every year.

If a person has concerns about a tree, they can send a sample to the KSU tree service to get verification of the disease.

Pine trees are not native to Kansas. They were brought in and many were planted in the 60s, 70s and 80s.