Why are my White Pines dying?
I have a row of White Pines in my back yard that are about 25 years old and about 30' tall. They've been very healthy until the last few months. I noticed the needles on one of the trees started turning brown during the winter and now the needles are almost completely gone. I took a closer look and noticed a hard white substance running down the trunk which I believe is sap. I see it on the other 6 as well and notice they are starting to get some brown needles. I've attached a few pictures. Any idea what might be causing this and is there anything I can do? Thanks Kevin
Westmoreland County Pennsylvania
Kevin: The resin running down the trunk could be due to the tunneling under the bark by coniferous bark beetles. Look for small pinpoint size holes. Also cut a six inch section off of the end of a branch. Feel the cut end...is it sticky or dry? If dry you are probably dealing with a complex known as white pine decline. Have there been any changes to the environment around the trees or have any chemicals/pesticides been applied around the trees? I would like to rule everything out, but the sap flow on the bark is diagnostic for bark beetle activity. Bark beetles typically do not attack healthy trees and instead focus on stressed or declining trees. It is not practical to treat for bark beetles because of the expense that would be incurred. Let me know if you see small pinpoint size holes on the bark..
Thomas, thanks for your response. I've attached one more picture so you can understand the location of the trees and a couple follow up answers. This row of trees is at the top of a small hill. There is a retaining wall at the bottom of this hill. The wall was existing but had to be rebuilt last fall. It was made of railroad ties that were rotting. The new wall is block but the installers had to cut a couple feet back into the hill. I don't know for sure but they could have disturbed the roots. I also apply RoundUp under and around the trees to control weeds but have been doing that for years. The only other stress I can think of is we had a very dry summer/fall last year.
As you suggested I cut about 6" off a couple branches. The ones that are dead or dying were dry. The ones that looked health or even a little yellow immediately started flowing with sap.
I also took a couple close up pictures I've attached that could be the pin size holes you mentioned. They are only seen on branches that are dead though.
What is white pine decline and is there anything I can do about it? Do I need to get the one tree that is almost dead (far left in the picture) removed so it doesn't infect the others?
Kevin: The photos confirm coniferous bark beetles. Raised planters/beds tend to dry out more readily which stresses the trees and predisposes them to attacks by bark beetles. Could you send your email address to firstname.lastname@example.org I can send you some information on white pine decline via email.
White pine decline is tied to high pH, drought, poor drainage, etc. White pine prefer a soil pH I found 5.2. The masonry work may raise the soil PH leading to decline. A soil test to measure soil pH is critical.