It is usually this time of year that people start coming in the store to buy some sort of fungicide because they think there is something wrong with their pine trees. The conversation always starts the same way, my tree is loosing needles, they are turning yellow and falling off, what can I do? 

At this point, I could sell them almost anything, but the truth is as long as the needles that are falling off are on the inside of the tree, everything is fine. Evergreens loose one third of their needles or leaves every fall. 

You will start to notice in the next few weeks about one third of the inner needles on the pine trees starting to turn yellow and falling. This happens to spruce, fir, rhododendron and every other type of evergreen as this allows them to send strength down to their roots for winter storage which in turn helps the plants sprout all their new growth in the spring. 

We are familiar with the beautiful fall colors from all the deciduous trees out there and that is why we don’t notice the evergreens unless we think there is a problem. Now if the yellowing needles are all the way out to the end of the branch and this is affecting branches all the way up, then yes it could be a fungus or an insect like spider mites. Neem oil is a fast and natural way to get rid of both these issues if you have a problem, but if the needles are only dropping from the inside of the branches and occasionally the lower branches all together if they don’t get a lot of sun, there is no need to worry.

Driving around the area this past weekend, I couldn’t help but notice that there are some leaves starting to change colors for Autumn and a lot of leaves falling without changing color at all. I have three trees in my yard, an ash tree and two maples that have dropped about half their leaves already. 

The ash tree is just dropping with no color change, the two maples have already turned orangey-red and dropping. Autumn leaf color is a phenomenon that affects the normally green leaves of many deciduous trees and shrubs. A green leaf is green because of the presence of a pigment known as chlorophyll, which is inside the leaf. But when chlorophyll is abundant in the leaf’s cells, as they are during the growing season, the chlorophylls’ green color dominates and masks out the colors of any other pigments that may be present in the leaf. 

Thus the leaves of summer are characteristically green. Red leaved trees like Japanese Maples still have chlorophyll but in much smaller concentrations that don’t block the natural leaf pigments. This is why non-green leaf trees don’t usually change to a different fall color. But now in late summer, as the daylight hours shorten and temperatures cool, the veins that carry fluids into and out of the leaf are gradually closed off as a layer of special cork cells forms at the base of each leaf stem. 

This is to prevent the tree from bleeding when the leaves fall off. As this cork layer develops, the water and mineral intake into the leaf is reduced, slowly at first, and then more rapidly. It is during this time that the chlorophyll begins to decrease and as the chlorophyll decreases the leaves true color emerges into the burst of color that amazes us every fall. In the case of my ash tree the cork has already formed and that is why the leaves have fallen off. 

Like the evergreens, deciduous trees turn colors and loose all their leaves every year sending their remaining strength down to the roots for storage over the winter. We know what colors each tree will be because it is the natural color for that tree. Northern Oaks have reddish leaves, Sugar Maples are bright orange, Red Maples (Acer Rubrum) are fire engine red, birch trees tend to be all yellow as would be my ash tree if there are any leaves left. Even though the leaves are pretty to look at, they do add valuable nutrients back into your soil when they decay. This is how nutrients are replenished in the woods each year. So don’t rake the leaves in your yard, mulch them up with the lawn mower and let them decay. Every year I see bags upon bags of leaves that people bag up and have carted away. Why pay someone else to take away nutrients from your lawn. But if you do, I know where you can buy some good fertilizer in the spring.