Abstracts

FERRANDIZ, L.S. 1988. The ABC’s of tree fertilization. Grounds Maintenance 23(4): 26, 28, 30, 134.

Knowing what makes up a good tree fertilizer is only half the story. To obtain a tree’s full potential, you must know how to properly apply the fertilizer. The article concentrates on the methods and equipment for soil-applied tree fertilizers, including surface, drill and liquid fertilizations. Use a spreader, drill or liquid injector, depending on situations like compaction, slope, etc. Fertilize the root-zone area evenly on a grid pattern for drill- and liquid-injection methods. (The root zone refers to the tree canopy plus the area extending one-third beyond the tree canopy.) Avoid the root flare. Fertilize in the fall. Use slow-release nitrogen fertilizers for most trees. Fertilize shade trees at 3 pounds of nitrogen per 1,000 square feet, at balance near 3:1:1 (for annual treatments). Reduce rates for conifers and broadleaf evergreens. Make the proper calculations to insure the correct fertilization rate. Don’t place fertilizers more than 8-in below the soil surface. Be careful of electrical lines, sprinklers and other potential underground problems.

KAYA, H.K. 1988. Princes from todes. Am. Nurseryman 168(5):63, 65-69.

Not all nematodes are bad. In fact, the possibility of artifically inundating areas with insect-parasitic nematodes to supress pests has tremendous appeal. Steinernema feltiae (also known as Neoaplectana carpocapsae) and Heterohabditis heliothidis are nematodes that possess nearly every desirable attribute of the ideal biological control agent. They are an effective alternative to chemical controls. They are safe to plants and warm-blooded animals. They are easily mass-produced and applied. They actively seek out susceptible hosts. They possess high virulence and infectivity, killing their hosts within 24-48 hours. And they have a wide host range. However, while each of these species is capable of killing more than 250 insect species under laboratory conditions, they are limited to moist situations favorable for their survival in nature. Nematodes by themselves do not kill their host insects. A lethal bacteria inside their bodies, Xenorhabdus, is released once the nematodes enter the insect hosts. While the Xenorhabdus bacteria kills the insect, it is incapable of entering an insect’s body by itself. It needs the nematode to penetrate the insect’s body cavity, and the nematode needs the bacteria as a food source. Thus the nematode and bacteria have a symbiotic relationship.

• © 1989, International Society of Arboriculture. All rights reserved.