In our office, we get many questions about trees which are sick or unhealthy. So, today I want to discuss tree health. Many trees have life spans that any human would envy. But in residential areas, these impressive life spans are often cut short by the rigors of urban environment. With attention to a few management practices this doesn’t have to be so. Pay particular attention to watering, fertilization and pruning.
Proper watering is critical when a new tree is transplanted. Water regularly, but be careful not to over water. This year, too much water has been a problem for many of our plants. The easiest way to determine if the roots need water is to check the soil two inches into the ground near the root ball. If the soil forms a ball when you squeeze it, the moisture is adequate; if the soil crumbles, it is too dry.
After a tree is established, normal rainfall usually will provide an adequate amount of water. But you still need to water during droughts or extended dry period similar to this past summer. When less than an inch of rain has fallen in a two week period and temperatures have reached 85 degrees, watering is needed.
Fertilization! Once a tree is established, apply up to 6 lb of nitrogen per 1,000 square feet of soil surface each year to maximize tree growth. Every three years, apply 3.6 lb of phosphorus and 6 lb of potash per 1,000 square feet. Apply fertilizer to an area that extends several feet beyond the canopy drip line. Research has shown that a tree’s roots may extend as far out as two to three times the height of the tree. One of two application strategies may be used. One is surface broadcasting which is most commonly used.
This is broadcasting dry fertilizers on the soil surface around the tree by hand or with a lawn fertilizer spreader. Beware, however, that broadcasting the entire amount of recommended fertilizer at one time will burn the lawn. Therefore, do not apply more than 3 lb of actual nitrogen per 1,000 square feet at any one time. Also, be sure to soak the fertilizer into the lawn to reduce the risk of injuring the lawn. Another method is to place fertilizer in holes. You can apply the full rate of nitrogen (6 lb per thousand square feet) at one time if you place the dry fertilizer in holes. Using a punch bar or a drill with a 2-inch auger, create holes beginning about two feet from the tree trunk. Place in a grid pattern two to three feet apart. The holes should be 12 to 18 inches deep and at a slight angle. Pour fertilizer directly into these holes. The amount you should place in each hole will vary depending on fertilizer formulation used.
Pruning! If you select the right tree and plant it in an area where it will be clear of buildings and walkways, the need for will be minimal. Once you achieve a good branch structure, you will only need to remove dead wood periodically. Try some of these practices and maybe you can increase the life span of your trees.