One of Several Pine Trees Sparse and Scrawny

Q. Why does my one pine tree seem so sparse and inadequate?  I purchased four Mondale pines and treat them all equally. But one of them looks so scrawny.  The other one shown looks healthy and appears to be robust.  Any thoughts on that? 

A. The usual reason for a pine tree being sparse and not full is that it is not receiving the same treatment as the others. Pine trees generally maintain needles on their branches until the wood gets to be three to five years old and then the needles are dropped from the older wood. This older branch is needle-less except for small branches growing from it less than five years old.

            The reason for canopy thinning is the loss of needles at a higher rate than they are being replaced. So bottom line for a pine tree becoming sparse is that the tree is not putting on enough new growth. Reasons for this include a lack of water, fertilizer, damage to the tree, or less likely, diseases or insects.

Pine needle brown dieback due to lack of water

            By far the most common reason is that the amount of applied water is not enough. So when you say you treat them the same it does not necessarily mean these treatments are all reaching the trees equally. But if there is inadequate water two things will happen; the tree will put on less growth and the needles will begin dying back from the tips.

            The first thing to do is to check and make sure that whatever is delivering water to the tree is not plugged. Secondly, make sure that water is not running off the surface to some other location. Just because water is applied to a tree does not mean it is getting to the roots.

Circling roots of semi mature tree due to circling roots
in the containers

            Remember, that as trees get bigger their demand for water increases. The increase is not simply a few gallons per year but is much greater because trees are three dimensional in their water use unlike a lawn. Unlike a lawn, when a tree doubles in size its need for water more than doubles.

            The next most common reason is that the roots of the tree never fully established into the surrounding soil after planting. This can be because the tree was too old for the container and the roots started circling and never established into the landscape successfully.

            It can also be because the tree was not firmly staked at the time of planting. Correctly staking a tree will immobilize the roots and help them to establish successfully into the surrounding soil. You should be able to push on the trunk and NOT see any movement of soil at the base of the trunk.  

            The next most common reason is damage to the roots or trunk. This will be far less likely than a watering problem but much easier to identify. This can be physical damage like construction, damage from chemicals like salts or weed killers, insect or diseases like collar rot.

            If the tree is being shaded by other plants and not receiving enough light (at least six hours a day) then these branches in the shade can drop their needles. If this is the case then some pruning to allow more light will help. If they are planted too close together then consider removing trees so the remaining trees will thrive.