Apple maggot disease is a common condition among apple trees caused by an infestation of the apple maggot insect. When left unmanaged, the disease can render fruit inedible. If detected early, however, the disease can be controlled. A number of options are available, some requiring more time than expense. Knowing when the pests emerge is important to be able to effectively prevent a substantial outbreak.
Cause of Apple Maggot Disease
The apple maggot pest, specifically the female, transmits apple maggot disease when she lays an egg in an immature apple. According to the University of Minnesota Extension Service, the pest has clear wings with unmistakable dark marks and white stripes on the abdomen. In adult form, it is one-quarter inch long.
Effects of Apple Maggot Disease
The University of Minnesota Extension Services states that apple maggot disease causes two types of injury to apples. External injury occurs causing the fruit to become sunken, dimpled and discolored. Internal injury, the more serious injury, occurs as a result of maggots tunneling through the fruit. It discolors the pulp of the fruit and ultimately causes it to rot.
Management with Chemicals
You can use insecticides to manage the apple maggot pest. Look for products that contain esfenvalerate. If using this method, it is critical to apply the product at the correct time. Apple maggots begin to emerge around July 1, and insecticides should not be applied before that time. You must also give the chemical enough time to break down any residues to safely harvest the fruit.
Managment without Chemicals
A few products are available to treat apple maggots without the use of chemicals. Red sphere traps, for example, have the appearance of an apple, hang from the tree and come with a feeding lure that attracts maggots to the trap. Apples can also be protected from apple maggot disease by placing plastic bags over each apple. The bags should be loosely tied or stapled at the stem with the bottom corner cut to allow moisture to escape.
Management with Proper Sanitation
Follow good sanitation practices to decrease the population of apple maggots. Always remove apples within a few days after they have fallen to the ground. Monitor for fallen apples both after a harvest and during the growing season. This is important because it prevents any larvae from entering the soil, where they pupate. Apple maggots pupate underground during the winter months.