Image Source: Brian Bagnall - The Outdoor Circle
"How To Plant A Fruit Tree
How To Fertilize
Top dress with fertilizer at planting and every 8 to 12 weeks with a type that has a 3:1:2 ratio of Nitrogen (N), Phosphate (P) and Potassium (K) for optimal growth of the tree for the first year or two.
Fertilizer should be applied in a wide circle around the tree, starting at the drip line and extending out. The idea is to encourage the roots to grow away from the trunk, become anchored and seek nutrients. The canopy of the tree generally follows the root growth.
When trees reach fruiting size change the fertilizer to a type with a ratio of 1:1:3 N:P:K. This will slow leaf and branch growth and encourage flowering, fruit set and fruit development.
Continue to mulch with composted or fresh leafy plant material to provide humus, the organic component of soil composed of decomposing plant material in the soil by microorganisms. Humus works with the soil to hold nutrients around the tree longer. Mulch will keep soil temperature lower and discourages weeds.
Dolomite (agricultural) lime, or Calcium can be important to apply to some of your fruit trees, especially avocados. Having your soil tested is good practice to ensure healthy growth. Minor and trace nutrients should also be applied annually or semi-annually, depending on rainfall, species and location. Some fertilizer formulations may contain minor nutrients along with N-P-K, such as “palm-citrus special,” and others.
We recommend Integrated Pest Management on fruit trees, this method is used in order to first identify and understand the pest and reduce the damage it causes; rather than eliminate the pest. Using strong broad spectrum pesticides kills all insects, good and bad, this practice eliminates beneficial insects that can help to reduce populations of the pest insect.
Aphids can be controlled by horticulture insecticidal soaps and oils. Mites can be controlled with wettable sulfur powder. Many common fungi can be controlled with Kocide; a wettable powder containing Copper, a minor nutrient needed by trees and a natural fungicide. Caterpillars can be controlled with B.T, Dipel or Thuricide; a naturally occurring bacterium that only affects the caterpillars."
Source: Plant It Hawaii (2020) https://www.plantithawaii.com/tree-care