My Conifer Needles Are Turning Yellow
I receive many calls in the fall concerning the abrupt discoloration of the interior needles in many different types of conifers. The good news in most cases; is that this is a normal characteristic of many different conifers in the fall, and not some fatal disease.
In the fall we are used to seeing deciduous (broad-leaved) trees showing their brilliant colors. However, when we see this on conifers it does not appear normal, and becomes alarming. Unlike their deciduous counterparts, evergreen conifers only discard a portion of their foliage each fall.
For example, pine trees tend to keep 1-3 years of needles active, and in the fall the older needles turn a yellow-brown before they are shed. The pine species showing the most brilliant color change in most years include white, Austrian, and Scotch. The color change is also noticeable on arborvitae and sometimes spruce. This color change occurs each year, but some years it is more eye-catching.
As long as the color change is in the inner portion of the tree and in the fall, you should have no worries. If you are seeing needle discoloration on this year's growth or at a different times of the year than fall or winter, then you should send some samples into the disease clinic to see what is happening. So instead of worrying, enjoy the brilliant yellow fall color of your conifer trees.