New research suggests wrapping apples with plastic sandwich bags can keep the bugs from getting inside the fruit.
IF YOU BITE into an apple and notice half a caterpillar smiling back at you, the extra protein is compliments of a codling moth. If, on the other hand, you’re greeted by the smiles of several half-eaten worms, you’ve just snacked on apple maggots.
Codling moths lay their eggs on twigs, and occasionally, on developing fruit. After hatching, the caterpillars bore into the apples and tunnel to the core before heading out the other side, leaving a trail filled with reddish frass (a polite word for bug poop). You can eat the apples after cutting out the bad parts, but they won’t keep.
Apple maggots, on the other hand, are fruit flies. The female lays several eggs directly into each fruit. After hatching, the maggots bore throughout the apple, creating irregular, winding tunnels that turn brown, eventually rendering the fruit inedible. In the past, I covered the fruit with apple-maggot barriers (actually pantyhose footies) to prevent infestation. The barriers were 100 percent effective against apple maggots, but the codling moths were able to bore right through the material to gain entry to the apple.
Spraying the barriers with a nontoxic crop protectant, available online under the trade name Surround and derived from kaolin clay, will prevent the caterpillars from entering the apples. Unfortunately, to be effective, beginning in late May, you have to spray the barriers every two weeks, as well as after every hard rainfall. If you get lax about your timing and skip a few of the sprays, as I did, you end up with a harvest of caterpillar-infested apples.
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Fortunately, recent research from the University of Minnesota Extension found that covering apples with plastic zipper sandwich bags is almost 100 percent effective at preventing apple maggots and codling moth larvae. Evidently, the fruit is not harmed by sun shining through the plastic, and the apples even tend to ripen earlier when bagged this way.
Generic-brand bags work fine, but don’t use the fancy slide-zip type. Before you begin, seal each bag one-third of the way across, and staple it at the top so that the staple is perpendicular to the seal. Make small slits or cut off the tips of the corners at the bottom of the bag to allow water to escape. Slip the bag over the apple so the apple stem is lined up next to the previously applied staple. Seal the other side of the bag, and apply another staple on the other side of the stem, again perpendicular to the seal. The two staples will be about a half-inch apart, with the apple stem in the middle. This helps ensure that the bag will remained “zipped.”
The bags should be applied by late May to early June, while the fruit is about a half-inch in diameter. Rub the fruit with your fingers to remove any hard-to-spot codling moth eggs that might already have been laid on the apples.
Admittedly, covering every apple on a good-sized tree is a Zen experience. Make the job easier by thinning the fruit to only the biggest applet per cluster. This will not only limit the number of apples you need to cover, but will result in bigger, higher-quality fruit. I don’t try to cover every apple, but I protect enough to ensure I’ll have plenty of bug-free apples to enjoy in the fall.
I haven’t tried this method yet, and my worry is that I’ll knock a good number of the apples off until I get the hang of it. The good news is that if it works as well as the research indicates, I’ll be rewarded with a bumper crop of delicious worm-free, homegrown apples. The only downside is that I’ll miss my neighbors’ surprised expressions when they saw my tree covered in pantyhose footies.