The technique I decided to try for growing organic apples is called "bagging", in simple terms, this just means putting a bag over your apples and pears (I've been told it does not work with soft fruits like peaches). The bag acts as a barrier preventing most insect pests and some diseases from damaging your fruit.
This picture shows the typical differences between bagged and unbagged organic apples. The one in the middle was not bagged while the others were. Bagging is probably the best current method of growing organic apples and pears in the Northeast where plum curculio (destructive beetle) thrives. The apple spends its entire growing life inside a zip lock bag. Yes, it looks ridiculous but it works! No chemical pesticides, fungicides, or fertilizers are used in my orchard unless they are organic approved.
So how exactly is this done, what kind of bags should you use, how much does it cost, and how much time does it take?
First, the Japanese have been doing fruit bagging for decades from what I've been told. In Japan a single perfect bagged apple can fetch as much as $10. They supposedly use paper bags tied with string. The idea of using paper bags is intriguing, after all they are biodegradable and should be inexpensive. However I could not find any in the appropriate size nor could I understand how they would hold up to rain and wind, I also wondered if such bags would restrict the light the fruit requires to properly ripen, and I don't like the idea of string tying every apple. (It turns out they remove the bags 3 weeks before harvest for proper coloring, something I do not have to do with my method). Here in the United States, based on what I've read, people generally use nylon footies or zip lock bags. Since nylon footies have been reported to not work as well, and they block light and cost more, I decided to go with zip lock bags. I've successfully used the generic zip lock sandwich bags from Walmart, but the lowest cost solution I could find was the 500 count box of real zip lock sandwich bags they sell at Costco (and probably similar stores). These have a final cost of 1.6 cents ($0.016) each and can even be found for 25% less than that with a coupon. Similar bags can also be purchased wholesale. Zip locks offer a very strong barrier that allows full light through. The first reaction fruit growers have to this idea is always "doesn't the fruit cook in the bag?" The answer is no, hard fruits like apples and pears are not adversely affected by the bagging at all. As I will describe, I do clip off the corners of the bag, but this is not for ventilation, they don't need ventilation, this is for drainage only in case rain manages to get in the bag (and it will).
Summary of 1995-1998 Apple Bagging Studies
This is how I do it... first determine how many fruits you expect to have and how many you would like to bag and go buy the appropriate number of bags. You can do this during the winter months or wait until the last minute when you can actually see the blossoms and get a better idea of how many you'll need. It is best to prepare the bags ahead of time, trust me on this, it will take much longer if you prepare the bags "in the field". While you are relaxing, perhaps watching a little TV, you can prepare all of the bags, even better if you get the whole family involved. To get started I recommend doing them one at a time, take each zip lock sandwich bag, using sharp scissors (they need to be sharp) clip the bottom corners off, enough so that water can easily drain out of the bag (cut the corner diagonally, about a centimeter or 1/4 inch up from the corner), then pull the zip lock open just a little bit (1-2 inches) in the middle (if you don't open them first, they are hard to open after you cut the top off), then take the scissors and cut off the heavy plastic pull tabs above the zip lock, you can do this by starting a cut and then just pulling the bag - it should come right off almost instantly in one quick tug. Cutting the tops off makes the bags lighter and prevents water from accumulating at the tops of the bags, both are important.
Once you have mastered the basics, you can do this all even faster. It helps to have at least two people working on it, one can do the corners, while the other does the tops. It is possible to hold many bags at once and cut the corners off all of them at the same time, just be careful to line them up.
Now that you have your bags ready to go, wait until after blossom and petal fall. Put them over the newly forming apples as soon as they show anything a bag can hold to, they can be tiny and still hold the bags. Its important to get the apples bagged before any plum curculio damage. I like to center my bags around each fruit and slide the zip lock shut as far as possible from both sides, right up against the stem. Only bag the "kings" - these are the biggest and strongest apples in a given cluster, usually in the middle of a cluster. Cut off all or all but one of the other apples in the cluster. You are essentially killing off 80 to 90% of the apples on your tree - this is called thinning, and you do it to protect the tree and to grow the highest quality, largest fruit possible. I've been told that the total weight of apples produced by your tree is going to be about the same regardless of the number of apples, so thinning helps ensure you end up with nice big apples. Also heavy clusters can damage the tree. Don't leave apples to grow where they are going to damage the tree or bring scaffold branches down below horizon (they may not set fruit the next year), or ruin your central leader by bending it over. The reason for optionally leaving one extra apple per cluster unbagged is that the tree will send out a hormone in late May or June that naturally thins out the fruit - this is known as "June drop". If you thin too many, you may lose some of your bagged apples during June drop. However it may not be worth it to leave any extra apples, the kings are so strong that the natural thinning hormone typically does not cause them to drop, and having extra unbagged fruit either on the tree or on the ground, can contribute to the spread of insect pests and disease. You should follow normal thinning procedure, sometimes entire clusters should be removed to allow proper spacing between fruit (some recommend no less than 6 inches between fruit).
Some people staple their bags, this seems like an unnecessary waste of time and resources to me, from my experience the zip locks will stay on even in severe winds and thunderstorms. A few of the bagged apples are going to fall off, but again from experience the apple was always still in the bag, in other words, the zip locks have never come off my fruit, so I do not staple the bags.
For a small scale home orchard, there is no question in my mind that bagging is the way to go. I've considered alternatives like the clay/barrier sprays such as Surround, but bagging seems easier compared to repeated sprayings, and bagging is also less expensive and more effective. I especially love the idea of "one and done" that comes with bagging, you do it once and that's it for the whole season. In most cases the home orchardist is going to hand thin their fruit anyway, so why not do the bagging at the same time, you won't really add much to your existing routine. I know of one person that has over 60 mature trees and he bags them all. Of course you could always only bag a few trees and expand from there in the future if you think its worthwhile. You could also just bag some of the fruit on any given tree, no one said you had to bag every single fruit. Another idea I had was that if you had so many trees that you could not handle it all yourself, and you give away a lot of the fruit anyway, you could offer an "adopt a fruit tree" program on craigslist for example, where someone local that was interested could bag some of your fruit for you in exchange for say half of the crop - this actually seems like a great idea to me, get other people to do all of the work but still benefit from getting at least half of the produce in the end, plus you will know that all of the fruit is being fully appreciated, you will have a chance to teach others, and make a few new friends. This could be just the sort of unique opportunity someone (or even some organization) in your community is looking for.
Give bagging a try and see what you think!
UPDATE: A few additional notes from the field... Some people report that zip locks do nothing to deter earwigs and may actually attract them. There is a very simple organic solution to this problem - put a small ring of tanglefoot or similar sticky barrier around the trunk of your tree, this product is great and it lasts all season, it will keep crawling insects from ever getting to your fruit, protecting you from many different species. It is also worth mentioning that some people take an additional step in preparing their bags, they snip the middle of the zip part so that when you put it on the apple stem it hugs it tighter, I think this is a pretty good idea and I will try it for some of my bags this year. One final concern is that some people have reported some brown/black rot inside the bags. I've seen this on some of mine as well. I'm not sure yet if this is a fungal disease or something else, also not sure if it is made worse (or better) by the bagging -- I've seen the same thing on unbagged apples. I think a very early (bloom/petal fall) pre-bagging spray of organic fungicide (Greencure) could help - obviously don't spray while the bees are active. Some think this may also be improved with increased ventilation (bigger cuts on the bottom of the bags). Maybe I'll experiment with different size cuts to try to find the "sweet spot". Finally it is worth noting that some have had success bagging peaches when using the footies (I do not grow peaches so I wouldn't know).
