Apple maggot is a problematic insect for Clinton County fruit growers this time of year, and can also wreak havoc on apple trees in your yard.
With a little bit of management, you can protect your trees from this fly so you can harvest more apples at home this fall.
The apple maggot fly (Rhagoletis pomonella) is slightly smaller than the average housefly. It can be identified by its wing markings, which have black bands in the shape of an upper-cased letter F. In our region, the adult flies can usually start to be found at the beginning of July, continuing through August.
Newly emerged adults feed for a week, then the females lay their eggs into the apples. This injury appears on the fruit surface as a small dimpled sting on the surface of the fruit.
Once the eggs hatch, the larvae feed and tunnel through the fruit. The misshapen fruit will often fall to the ground prior to harvest. From there, the larvae pupate and burrow into the ground where they will overwinter and emerge as adults the following spring to continue the cycle.
There are a number of strategies a home gardener can use to reduce the amount of fruit they lose to apple maggot. Remove injured apples as they fall from the tree, so the larvae will not have a chance to pupate and overwinter in your garden.
You can also purchase red, sticky spheres to trap the adult flies before they have a chance to lay eggs into your fruit. These traps are usually placed in commercial orchards just for monitoring purposes, but can be used in the home garden to reduce fruit damage if traps are placed at a frequency of one trap for every 100 fruit you have on your trees.
Red, sticky traps baited with apple essence can be used to monitor, and potentially even trap out, apple maggot adults. (Note the apple maggot flies stuck to the trap in the photo).
Another nonchemical strategy would be to cover your fruit with small plastic baggies as they grow. This strategy, while time consuming, forms a physical barrier between the developing fruit and any insect pest that might try to damage it. While obviously not practical for a commercial orchard, you might consider this strategy for your backyard trees if you only plan to harvest a few dozen fruit.
Finally, you might also consider chemical options for controlling this pest. The red spheres can be used to help time these applications. Generally, treatment is recommended after five flies are caught on a red sphere trap that has been baited with an apple scented lure. These treatments can be repeated if trap numbers continue to remain high after the initial treatment.
There are both conventional and organic products available to treat apple maggot. Before you purchase any pesticide, be sure to read the label to make sure it can be used for apple maggot, and for instructions for how to properly apply it.
Mike Basedow is a regional tree fruit specialist with the Cornell Cooperative Extension Eastern NY Commercial Horticulture Program. He can be reached at email@example.com.