Bag Apples for Spray-Free Apple Maggot Control
Plant researchers around the world cover various parts of plants to protect them from insects, diseases, or to prevent pollination. Paper bags are the most common means of providing protection.
Some Asian countries use the same concept to raise high quality fruit. South Koreans place a paper bag over apples, peaches, pears and grapes to produce blemish-free fruit. Japanese do the same and are able to obtain a premium price of three dollars per apple for this high quality product. Washington state apple growers capitalized on this process and bag approximately 15 million apples a year for export to these Asian markets.
A research project was developed to try covering apples with commonly available bags to protect them from the apple maggot by Larry Zilliox, Extension Educator and a group of Master Gardeners. They used two commercial orchards and five home backyards for their research sites. All apples were bagged between June 1 and June 18. The apples were approximately the size of a quarter and could be distinguished from the ones that would be aborted.
They set up five treatments to evaluate the effect of bags or other covering in controlling apple maggot problems. The treatments were: plastic bags, brown paper bags, commercial paper bags (gray bags, specifically used for bagging fruit in orchards), plastic film ("Saran Wrap"), and zipper closure plastic bags plus the control of no treatment.
The bags were attached with twist ties or masking tape. Paper bags were a real challenge due to the amount of paper that had to be secured around the stems. Five percent of the apples were knocked off in the process of bagging. At the second commercial orchard they resorted to stapling the bags closed. This worked much better and improved the efficiency of applying the bags.
The most efficient method was stapling the zipper closure plastic bags. They could apply 30 plus bags per hour. They stapled the bag one third of the way across the zipper, slipped the plastic bag over the apple, then zipped it closed. The apple stem, aligned with the staple on one side, was then secured in place by another staple on the other side.
Preliminary results from the first year testing of this concept look very positive. The apples protected in either type of plastic bags colored up properly, had excellent flavor and size and best of all, there was no apple maggot damage when compared to the controls. The bags also appeared to prevent disease symptoms on the fruit.
They envision home orchardists stepping into their backyard on a late spring morning to survey their still-healthy apple crop. Using ordinary household plastic bags, they could bag 30 to 40 apples in an hour to protect them from insects and possibly diseases the rest of the season. Once they bagged the anticipated number of apples needed, they could forget the rest of the apples on the trees.
Source: Zilliox, L., Extension Educator-Horticulture, University of Minnesota Cooperative Extension, Douglas Co. Yard & Garden Line News, Volume 2 Number 1 January 1, 2000, http://www.extension.umn.edu/yardandgarden/YGLNews/YGLN-Jan0100.html
Bagged apple. Photo credit: Larry Zilliox