There are many ways to control worms in apple trees from hanging sticky traps to spraying the trees with a solution that will kill or repel worms. The type of method that will be most effective will depend on the type of worm problem you have.
Two of the biggest threats to apple trees are maggots and codling moths. Apple maggots are white worms that eat the flesh inside of maturing apples. These are the toughest worms to detect from the outside. The apple maggot is the larva of the apple maggot fly. They are white or yellowish in color and they can grow up to ¼ of an inch long. The adult apple maggot fly is also ¼ of an inch long. The adult apple maggot is quite easy to spot due to its color. It has yellow legs and it is black in color. It also has yellow markings across its abdomen and bands that appear in a zigzag pattern across the wings.
It only takes a second or two for the apple maggot to lay a bundle of eggs on an apple or even a pear. It lay’s its eggs in punctures in pear or apple skin. Apple maggots can ruin the apples in your apple tree if you do not stop them before they start. One of the best ways to control apple maggot populations in and around your apple trees is to prevent the fly from laying eggs in the first place. This can be accomplished by using sticky traps. Sticky traps are available at just about any store that sells camping gear, home and garden products, super stores, and even drugstores.
Sticky traps are made from either a red ball or a yellow rectangle. This ball or rectangle is covered with a sticky material that traps the fly with even the slightest touch. You should hang the sticky traps in and around your fruit trees in late June. They should remain in place until after harvest. It is best to use at least two traps per tree for a dwarf or semi-dwarf and at least four traps for standard trees. It is important to keep the sticky traps clear of surrounding branches and discard all fallen fruit immediately.
You can always tell if you have a codling moth infestation just by looking at the crevices in the bark of your apple trees. The codling moth spins its cocoon right in the crevices of apple trees. The codling moth larva is pink in color with a brown head and it is around one inch long. The adult codling moth is a grayish brown color with brown lines on its forewings. It has pale, fringed hind wings with a wingspan of around ¾ of an inch.
The adult lays white, flat eggs in a number of places such as on fruit buds, leaves, or twigs. The larvae of codling moths make their way into apples through tunneling. Once they are just inside the apple, they continue to tunnel their way through, eating as they tunnel along.
There are several effective methods of controlling codling moths. In late winter or early spring you can spray dormant oil on trees before leaf budding. This will suffocate the eggs. Once the blossoms begin to open, meaning once they “show pink” called “open cluster,” position sticky traps with pheromone lures to catch the moths. If you notice a dozen or more moths caught in a single trap during the 10 to 14 days after bloom time, use Ryania, a botanical insecticide made from the ground stems of Ryania speciosa, a native plant of tropical America, in a spray as the blossom petals start to fall. To kill the newly hatched larva, spray Bacillus thuringiensis (BT), a live microorganism that kills insects, and light horticultural oils every seven to 10 days later in the season.
You can also control codling moths by attracting the parasites of codling moths. Simply plant butterfly weed (Asclepias tuberosa) nearby because butterfly weed attracts codling moth parasites of all kinds.
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