Pre-Blossom

• In early April, before the blossoms have opened, spray the tree with Superior Oil to repel aphids, scale and red mites. A 2-percent solution is recommended for good coverage. Spray on a calm day so most of the solution stays on the tree, and is not blown away.
  
  

After Blossom

• If you planted disease-resistant trees, your spraying will be greatly reduced. For those who are not so fortunate, spray a fungicide every 10 days until a week before harvest. Once the blossoms are finished and have dropped to the ground, spray the tree with an insecticide called Imidan. This will prevent against most of the common pests known to apple trees.
  
  

Second After-Blossom Spray

• Since many common pests go through an egg-laying and hatching cycle, it is not good enough to spray the insecticide just once. Ten to fourteen days after the first application, spray the same insecticide again to kill off any remaining pests. Spray when there is little wind, during the cooler times of the day.
  
  

Red Spheres

• Sticky red sphere traps will defend your trees against the dreaded apple maggot. Most dwarf apple trees will need just one trap, while a standard tree can use four or five traps. Figure one trap for every 150 apples. The apple maggot will appear as a black fly, a little smaller than the common housefly, and will lay eggs in the apples early in June. The eggs develop within the apple, burrowing under the skin as maggots to leave the apple mushy and unappetizing.