Description

• All plants, including trees, require certain nutrients to grow and maintain optimal health. These nutrients are placed into two groups based on how much a plant needs. Macronutrients are required in relatively large amounts and consist of nitrogen, phosphorous, potassium, calcium, magnesium and sulfur. Micronutrients are only required in small amounts and include iron, zinc, copper, manganese, boron, chlorine and molybdenum. In addition to nutrient supplements, trees also need pest control from time to time if an infestation is causing damage.
  
  

Fertilizer Types

• Many organic and inorganic commercial tree fertilizers are available. Inorganic tree fertilizers are typically water-soluble and can deliver the required nutrients quickly to the tree. This can be useful if a nutrient deficiency has been identified or when a tree's health is at risk. Inorganic fertilizers are usually labeled with the percentage or total weight per 100 lbs. of the three major macronutrients: potassium, nitrogen and phosphorous. Organic fertilizers release nutrients more slowly. They require moisture and bacterial digestion before the nutrients are available to the tree.
  
  

Fertilizer Application

• You have two basic methods of applying a tree fertilizer. The simplest and least expensive method is to apply the tree fertilizer directly to the surface of the soil. Applying tree fertilizer underneath the soil's surface can be more difficult but it delivers macronutrients directly to the roots and it aerates the soil around the tree. Deciduous trees typically should be fertilized during the growing season and only once every two years. Fertilize evergreens less often and only in the spring.
  
  

Calculations

• It is helpful to calculate how much fertilizer you will need before deciding upon a tree fertilizer product. An easy method is to measure the trunk's diameter 4 to 5 feet from the ground and use 1 lb. of tree fertilizer for every inch.
  
  

Pesticides

• Insects and other pests usually attack a tree that is already sick or weakened. Disturbing the tree's root system, drought and improper planting can all make a tree more vulnerable to pests. Signs of a pest infestation include decaying wood, holes in bark or leaves, swellings or sunken areas on the branches. Properly identify the pest before choosing which pesticide to use. Ask a professional if you are unsure. Purchase the correct tree pesticide, insecticide or fungicide specific to your tree's health problem and follow manufacturer's directions for application.