Producing eating quality apples can be challenging for the home gardener, due to damage caused by insects (e.g., apple maggot, codling moth, plum curculio) and fungal diseases (e.g., apple scab, cedar-apple rust, sooty blotch). Many insects damage apples when they lay their eggs in developing fruit. Insect larvae can cause additional damage as they tunnel into the fruit. Wind-borne fungal spores can land on fruit leading to infections that damage fruit, reduce fruit aesthetics, or affect long-term storage.

Although insecticide and fungicide sprays can help control insect pests and diseases, regular spraying can be inconvenient and costly for homeowners. A non-pesticide alternative for protecting fruit is to encase developing apples in bags that provide a physical barrier against insects and fungal pathogens. You will need a ladder, scissors, stapler, and Ziploc® sandwich baggies.

Fruit that you do not bag will likely be damaged from insects and disease. Blemished fruits should be removed (whether they fall to the ground or remain attached to your tree) and destroyed. Disposing of blemished fruits will help limit overwintering of insect pests and disease-causing organisms, thus reducing insect and disease problems next year.

Step 1: Thinning

This picture shows 6 fruit clusters on one spur. When the fruits are the size of a pea, the fruits should be thinned (removed), to one or two fruit per fruit cluster. The thinning process must be done. Remember you are saving your apple tree, not killing it. If too many fruits remain on a tree, the branches become too heavy, the mature fruits will be small, and the tree will only produce a decent crop every other year.

Step 2: Bagging

As you are thinning the apples, bag the remaining apples. If you wait too long, fruit tree pests will be active and you may find your fruit has already been damaged. Slip a plastic Ziploc® sandwich bag over the apple, and then zip it closed. The apple stem, aligned with the staple on the one side, is secured by another staple on the other side. A weep hole is cut on the bottom left to let moisture out. 

Step 3: Relax, enjoy the summer.

The bags act as a physical barrier to protect the fruit against attack by summer insect pests and fungi.

Step 4: Bag Removal

Remove bags 3 weeks prior to harvest so fruit will color properly.

Step 5: Ready to eat.

It’s manageable to ‘bag’ about 50 apples or one bushel from a tree.

Photo below shows where Apple maggots create wormy, dimpled, and deformed fruit.