Pin Oak: Popular Shade Tree

The beautiful oak, which may reach heights up to 80 feet, grows from one of the smallest acorns produced by our commonly planted oaks. Although the pin oak is one of the most popular trees for home landscapes, it is also a native oak. The tree prefers rich moist soil, but is well adapted to many sites. In addition to its small acorns, there are many other characteristics which have made the pin oak a popular tree. Among the oaks, it is probably one of the easiest to transplant. This is because it has a relatively fibrous root system.

The shape of the tree is quite picturesque. It has basically a pyramidal outline. Upper branches tend to be upright while middle branches are horizontal and older, lower branches droop gracefully. In a lawn where there is plenty of room the lower branches may droop to touch the ground. The pin oak is a rapid grower. A healthy tree may reach 20 feet in seven to eight years. It has many branches making it a full tree providing excellent shade.

The fall color of pin oaks also is very appealing. It will normally change from green to reddish green to scarlet. Leaves of young trees, or young shoots of older trees often hold their foliage until late fall or even spring. Pin oaks growing in a good location have few problems and may live for several hundred years. One of the most common problems associated with pin oaks is their inability to tolerate alkaline soils. They prefer acid soils with pH readings between 5 and 6.5, and respond dramatically to neutral or alkaline soils by developing yellow foliage and stunted growth.

This condition, called iron chlorosis, results from an inability of the tree's roots to absorb iron from the soil under these conditions. The problem often appears on old building sites where trees are planted into soils where mortar or remains from old buildings may have been mixed into the soil. Sometimes only half a tree may show these symptoms. There are several ways to treat soil for iron chlorosis. Soluble forms of iron are available under several trade names called iron chelates. These may be used carefully according to manufacturer directions as either foliage sprays or soil treatments.

They will provide a quick response and greening, although they will not change the soil acidity. Therefore, some other treatments to gradually make the soil more acid may be necessary later. Iron sulfate (ferrous sulfate) may be applied to the soil around the drip line of the trees to provide more iron to the roots as well as help to make the soil more acid, it is generally mixed into water at a rate of about one pound per gallon. This is applied in holes dug around the outer edge (drip line) of the branches.

During the growing season, apply about one-half gallon of solution every three feet. If applied during the dormant season as much as one gallon per hole may be used. Small trees without branches large enough to indicate a drip line need only one-half to one gallon per tree, depending on size and time of year. Before tilling the holes with soil be sure to add another gallon or two of water to wash the material farther into the soil as well as to dilute the solution. It is also helpful to water the soil surface after treatment so any spilled solution is diluted and will not cause burning of grass and other plants.

http://en.wikipedia.org/wiki/Pin_oak