Growing Apples Without Insecticides

Why are apple orchards, both large and small, so dependent upon chemical insecticides? Is there a way out? One expert looked into ways of growing apples without them.


| August/September 1994



145 growing apples - holding three

Apples come in many varieties, and some are more resistant to pests and disease than others.


MICHAEL THOMPSON/COMSTOCK

Statistics show that apples are the most heavily sprayed fruit grown in the country. If this is necessary, what must the apple crop have been like several hundred years ago, before chemicals were in widespread use? The question of growing apples while bypassing the world of chemicals had been germinating in my mind for several years. It had its roots in my own orchard observations regarding apples and pests, particularly the insect kind. 

My interest can be traced back to the early 50s when I was growing up in Chicago. We didn't have orchards in the city, but we kids could find green apples to occasionally throw at each other in a spring training-like exercise that occurred each fall, presumably in anticipation of winter's snowball fights. I knew back then that there were more than just fancy red store-bought apples, since we were not allowed to take table fruit for ammunition. In the mid-70s, I had graduated from college and taken a job in Connecticut, and I was lucky enough to buy my own home with sufficient land to allow a garden and a respectably sized orchard. In 1978 I planted four apple trees and taught myself how to graft by practicing with pruning on some wild crabapple trees. To my surprise, about one third of these attempted grafts were successful. I contacted the State Extension Service for additional information. I was amazed to find what I could order through the mail. Over three hundred different varieties in the form of scion wood1 as well as size-controlling rootstocks were just an envelope and a few dollars away. The rootstock would allow me to create trees that would grow anywhere from four to 24 feet in height. Even more amazing was my discovery of the U. S. Germ Plasm Repository for Apples at Geneva, New York, where more than 3,000 varieties are currently being kept for future plant breeding experiments. I read and reread the available literature and spent many long winter nights deciding which of the many varieties I should order.

After reading about the characteristics of these different varieties, I decided that my orchard should be a "preservation orchard." I would specialize in Old American Apple varieties, most of which have been traced back several hundred years. The apple descriptions I found were all tempting and I managed to select what I thought would be 50 of the best varieties. One wonders what distinguishing characteristics or attributes our ancestors saw in each of these varieties that made them worth preserving through so many generations. My plan called for the use of a strip of land that paralleled my driveway for the orchard. It was 300 feet by 50 feet and would comfortably hold an orchard having 18 rows with four trees in each. I planned on adding 10 different varieties each year, completing the orchard in the fifth year when the trees from the initial planting would be ready to produce their first fruit.

The economy of grafting was soon obvious, for by combining a selected variety with a size-controlling rootstock, I was able to create new trees for as little as $1.50 each. This was less than one-tenth of the asking price at the local nursery, and their selection was limited to only five or six of the commercial varieties. Things didn't go quite as planned and today the collection has more than 50 varieties with a total of 124 trees in two small orchards. Twenty-two of the different varieties are mature enough to produce fruit and it is my observations of these that started me thinking about our past practices of controlling insect pests without chemicals. I consistently observed that with respect to insect damage, not all apples were created equal.

Let me explain. First, I chose not to follow the spray schedule that was recommended by the extension service for home orchards . This appeared to call for too much spraying and I reasoned that I would never know what insect, pest, or damage I was eliminating if I did not first observe it on the fruit. I planned to spray less than half as much as the schedule suggested. My strategy was to see how much damage the crop would suffer with this reduced number of sprays and then decide if more spraying was required. Second, I withstood the temptation to obtain a pesticide license and decided that I would use chemicals that were available to the public and not as toxic to the environment. I assumed that by spraying all of the trees having fruit at the same time with the same spray I would harvest a crop that had about the same amount of blemished fruit from tree to tree and from variety to variety. Was I in for a surprise. Year after year I have observed that there are statistically significant differences among the varieties in terms of the amount of damage. The poorest varieties in the orchard (McIntosh, Red, and Golden Delicious) have as much as 50% of their crop blemished while the best performers (Earliblaze, Westfield Seek-No-Further, Hubbardston, and Wagener) have only 5% blemished. A similar finding holds for these varieties when you consider disease as well. Based on my observations over the past several years, I've ranked the 22 varieties that I have experience with in terms of their overall resistance to insects and disease. My Apple Variety Fact Sheet Table shows the results and should be viewed as representing average trends. As more varieties mature and produce fruit, I'll add their observed results to the list. This inherent ability of some of the varieties to resist insect attack is an important finding for apple lovers that could help us reduce our dependence on chemicals by being more selective about the varieties we decide to grow.

Having these observations documented in my notes, I began a systematic search for the reasons there should be such a disparity between the extremes on this list. At first I thought that the location of the varieties within the orchard was the answer. But a review of the orchard's layout showed that the three worst varieties were centrally located. This meant that any insects attacking these three would first have to pass trees of other varieties. Next, I thought that the ripening date of the variety might provide a clue, reasoning that the longer the apples remained on the tree, the more opportunity the insects had to do damage. A comparison of the average ripening dates, however, showed that this was not a significant factor. Finally, I thought that color might be the reason and noticed that two of my poorest varieties were also two of the most beautiful, brightly colored apples. While there might be something here, the correlation breaks down if one compares a Liberty with a McIntosh apple. Liberty is a more handsome apple yet it is much less attractive to insects than McIntosh. Color by itself did not appear to be the reason.





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