FINE PINE

It's not uncommon to see pine trees and assume they're dying. Many times, though, they're not dying at all, but rather going through routine needle fall.

To understand exactly what's going on, let's first look at pine growth habits.

At the end of each twig on a pine tree is a terminal bud. When the trees break dormancy in the spring, this terminal bud swells and elongates. From this bud, a new terminal branch begins to emerge, along with several branches that grow at 90 degrees from the new terminal. This new terminal branch and the lateral branches make a whorl of branches. Most pines and spruces produce one whorl of branches each year.

As the terminal twig and the lateral twig elongate, the pine needles emerge. All twig elongation and needle development is usually complete in May or early June. From then on, the new twigs harden and become stout. Next spring, the same process begins at the end of the twigs that emerged the previous year.

Depending on species and environment, evergreen needles will last one, two, three or four years. Then they will fall off just like oak leaves do each fall. What we have been seeing recently is the normal fall of last year's needles on white pines.

Several people have told me that they have never seen this happen before. I can assure you it happens each year. Just look at the ground under pine trees. You will usually find needles. They come from normal needle fall.

When pine trees are diseased, their needles often turn brown, just like ones that turn brown and fall off normally. How can you tell the difference between normal needle fall and diseased needles? Diseased trees will have brown needles on the current year's growth, that is, needles on the ends of the branches. Trees undergoing needle fall will have green needles at the end of twigs, while the brown needles will be on the previous year's growth.

While some people have been unduly alarmed, the concern about "dying" pines of late does have some validity. I have seen an occasional white pine succumb. Not much is known about why they do that. Scotch pine is susceptible to nematodes.

Only one evergreen -- Eastern red cedar -- is native to this area. All of the other evergreens in our landscape were introduced. These introduced landscape plants may not be ideally suited to our environment. This means that they could be stressed due to local environmental conditions.

For plants to grow vigorously, they need minimal stress. To reduce stress on evergreen plants -- and all plants, for that matter -- in your landscape, you must make sure you fertilize and water properly.

I recommend that you fertilize your landscape plants in both spring and fall with a good tree and shrub fertilizer, such as 19-8-10. It should also contain micronutrients. Be sure to follow label directions.

Improper watering seems to be a major reason why evergreens do poorly. Monitor soil moisture conditions by sticking your finger in the soil surrounding your landscape plants. When the soil is dry, water them. When the soil is wet, don't water them.

There is no formula for watering landscape plants. Watering frequency depends on rainfall, location of the plant in relation to buildings and other structures, presence or absence of mulch and weed barrier, temperature, wind conditions and cloud cover.

I have one other word of caution. Evergreen landscape plants transpire all winter long, especially when days are warm and sunny. Be sure to monitor soil moisture during the winter.