Fungicides

• Apples can come under attack from a number of different types of fungus. Fungi are parasites can cause unsightly fruit and leaves and could eventually affect the overall health of the tree and crop. Fungicides, such as captan and copper hydroxide, are used to fight common ailments such as rust and scab. Some fungal varieties can also cause varying types of leaf spot, which could lead to leaf drop and fruit drop before ripening.
  
  

Pesticides

• Just as serious as fungi are insects, which can attack trees and even kill them in some cases. Pesticides, such as malathion or permethrin, are used to control insect infestations on apple trees. They are considered safe for humans to consume, so make sure that whatever variety you choose is labeled for fruit trees. Common insects affecting apple trees include the coddling moth, apple maggots, various varieties of mites and scale insects.
  
  

Beginning Spraying

• The best time to start applying fungicides and pesticides is right after the temperature starts to improve in early spring. When you see the first green of the leaves in spring, start spraying, especially with fungicide. Fungus, if left unchecked, can take its toll on young leaves, especially if conditions are wet and cool. Generally, spraying should begin sometime by or during the middle of April, depending on your location.
  
  

Schedule

• Once the first sign of green appears in the spring, spraying should continue every two weeks at least through the summer. The only exception to this is when apple blossoms appear. At that point, if you are using a combined spray containing both an insecticide and fungicide, switch to a spray with no insecticide. Using an insecticide during this time could kill bees, which are responsible for much of the pollination in apple trees.
  
  

Stopping Insecticides

• Generally, it is important to stop spraying an insecticide on the tree as harvest nears. This allows the residue left behind from the pesticide to break down, further limiting the danger to humans. The label for the pesticide product used should advise the grower when to stop using it. Usually this is within several weeks of the anticipated harvest. Always wash fruit before eating, no matter when spraying was stopped.