browning needles on lodgepole pine

Asked August 27, 2018, 12:21 PM EDT

We have a 9' tall lodgepole pine that was planted about two months ago and I've noticed recently that needles on the interior of the tree are browning and dropping. The dying needles have dark stripes on them. I looked into a few possibilities but was hoping to get an expert opinion. Most of the tips of the branches seem to be green and healthy, which could indicate normal dropping of older needles, but the stripes gave me concern. I was initially watering it once/week with a 14 gallon "donut bag" that has two emitters. Then it was recommended to water it by hand with a hose, which makes it harder to gauge how much water it is actually getting. Can you recommend a specific watering plan for this tree, in case the cause it over or under-watering?
Pictures attached.
Thank you very much.

Clackamas County Oregon

4 Responses

This looks like normal needle drop on your lodgepole pine, possibly more than normal because of transplant shock. I don't see any signs of disease or insect damage on the needles, and, most importantly, the needles on the ends of the branches are green and healthy. If insects or disease were causing needle drop you would see it in all parts of the tree. This article gives additional information, Autumn Yellowing of Conifer Needles https://csfs.colostate.edu/2016/09/13/autumn-yellowing-conifer-needles-normal-process/.

You've been very diligent in watering your tree. That's very important for this tree for two reasons; 1. the tree has only recently been planted so the roots haven't grown into their new home and the tree hasn't yet established itself, and 2. we've had a very hot dry summer with prolonged heat waves. This makes it very difficult to keep our plants hydrated.

The donut bag is a great way to water. It holds 14 gallons of water which is great, is measured and releases the water over time. I agree about hand watering in that it's difficult to measure. You can also use soaker hoses looped around the tree.

Thank you very much, Anne. I think I'll continue the hose-watering at this point, or a soaker hose, since I found root growth beyond the drip line, and the donut waters under the canopy, closer to the trunk.

As far as the needle drop, the stripes on the needles are of no concern? Is dothistroma a possibility? The description of the needles affected by dothistroma resembles what ours look like, especially the stripes. Of course, it's just like looking up your own symptoms on the internet, you always find dire diagnoses. Just want to make sure I'm not overlooking anything.

Thank you for the quick reply from the initial inquiry!

Deb

Hello Deb

Thank you for your response.

I don't think this is dothistroma needle blight because: the tree as a whole looks very healthy, there's no sign of lesions on the other needles, and needles affected by dothistroma are green at the base and your shed and attached needles are all evenly colored. This article discusses this disease in our area, Dothistoma needle blight https://pnwhandbooks.org/node/3276/print. This article has a good discussion and good pictures of affected trees and needles, Dothistroma Needle Blight in Pines http://www.missouribotanicalgarden.org/gardens-gardening/your-garden/help-for-the-home-gardener/advice-tips-resources/pests-and-problems/diseases/needlecasts/dothistroma-blight.aspx..

I do see the spots on the needles, though, and am going to reassign this to someone with more expertise on tree diseases.

I think the previous answers by the Master Gardeners have covered it pretty well. Your new growth looks very healthy and the browning and loss of older needles is not unusual, especially in the transplanting year.