The Agent's Observations May 1997

Question: How much fertilizer do shade trees need, what kind is the best, when should it be applied?

Answer: Ornamental trees and shrubs planted in fertile, well-drained soil that are growing normally do not need extra nutrients. If they are not doing well fertilization may be helpful but only after the problem causing poor growth is corrected. Symptoms of poor growth may be light green or yellow leaves; smaller and/or fewer than normal leaves or dead spots; wilting of foliage; few flowers; short annual twig growth; and branch tip die back. These symptoms of poor growth may be caused by poor environmental situations like; inadequate soil aeration and moisture, or nutrition; adverse climatic conditions; wrong pH; or insects and diseases.

Normally the only nutrient applied to established trees and shrubs is nitrogen. Other situations like chlorotic leaves, manifested by yellowing of leaves but veins remain green, require specific applications of a nutrient, in this case iron. The amount of nitrogen needed will depend on the size of the plant. Measure the diameter of the trunk about one foot from the ground, apply 0.05 pounds of actual nitrogen/inch of trunk diameter. If a tree has a trunk diameter of six inches multiply by 0.05 to get 0.3 pounds of actual nitrogen. Divide the amount of nitrogen by the percentage of nitrogen content of the fertilizer to be applied. For example: 0.3 pounds of nitrogen applied as 21% ammonium sulfate would be: 0.3/21% = 1.43 pounds of ammonium sulfate fertilizer from the bag. Distribute the fertilizer evenly by measuring the distance between the trunk and drip line and multiply by 125%. This will determine the outer boundary radius for fertilizer application.

Distribute the fertilizer evenly in the outer 2/3 of this circle. For example: If the trunk is eight feet from the drip line, then the outer boundary will be ten feet, (8 X 125% = 10). Apply fertilizer around the tree or shrub in a doughnut shaped band 3.3 feet to 10 feet from the trunk, (10/3 = 3.3). Applications are best applied in early spring.

Question: I have a peach colored rose that has one blossom that is ' half peach and half white. Even one of the petals is half peach and white. How did this happen? Was there cross pollination?

Answer: No cross pollination. You have found what is known as a "bud sport." This is a genetic mutation of the bud tissue. In this case the tissue most likely lost the genetic code for the peach color, therefore in the absence of color white results. This is how 'Golden Delicious' apples came into existence. In the late 19th Century a branch of a 'Red Delicious' apple tree produced a yellow apple named 'Golden Delicious.' Buds were grafted into other trees and rootstocks and voila! 'Golden Delicious' apples are now produced worldwide.

Rob Call
May, 1997