Gardening: Use a variety of techniques to keep pests out of fruit trees

It’s time to think about fruit tree spraying.

Codling moths are responsible for the larvae that bore into apple cores. Apple maggots tunnel their way throughout an apple’s flesh. Cherry fruit flies lay their eggs in cherries and the white larvae burrow into the fruit, leaving you a little surprise.

Controlling these pests goes far beyond grabbing a bottle of insecticide. It starts with a program called integrated pest management that calls for non-chemical management techniques that reduce the possibility of an infestation, coupled with chemical control when the pests are present.

In a home orchard, pest management begins with keeping the orchard free of old fruit and leaf debris. Larvae hang out in old fruit and drop into the soil for the winter. Clean up infested fruit and send it out with the trash to avoid spreading the pests.

It’s not too late to apply dormant oil to smother larvae overwintering in bark crevasses and cracks. This highly refined mineral oil should be applied in the late winter or early spring before the tree buds swell. Spray the entire tree well, including the crevasses in the bark. Whenever you use this or any other pesticides, read and follow the label directions.

Getting the timing right for applying insecticide sprays involves understanding a little bit of the pests’ biology. In general, you must apply the spray before the larvae get into the fruit. Once they are inside, nothing will touch them.

Generally, cherry fruit flies are present from mid-May to the end of July, which means you will have to make multiple applications to get successive generations. Begin applications about May 20 to 25. Apply malathion every 10 days up to three days before you plan to harvest the fruit. If you use spinosad, an organic, bacteria-based spray, apply at seven- to 10-day intervals. Be sure to spray the underside of branches and leaves.

For codling moth, apply chemicals about 10 days after full petal fall (all petals are off) or 17 to 21 days after the tree reaches full bloom. You will likely need to make several applications. Read the label for exact timing of these applications. Remember that many conventional insecticides are toxic to bees, so apply them after all the flowers have gone or late in the evening after the bees have stopped foraging.

Apple maggots are such a problem in Spokane that there are warning signs on the roads leading out of town imploring us not to move homegrown fruit out of the area. The adult flies are active from June into October and are characterized by striped black and clear wings. Learn to identify the adult fly and then monitor for their presence with sticky traps available at garden centers. When the flies appear on the traps, begin applying the chemical according to the label directions.

Got trees taller than 10 feet? Call in a professional spray company that has the proper equipment to efficiently cover the whole tree safely while standing on the ground.