Selecting Pome Fruit Crops and Varieties - Growing Organic Orchard Fruits - page 150

Climate considerations. To reemphasize a critical point made in chapter 2,
climate sets the limits within which all other factors operate. In order to give
your organic orchard every chance of success, choose varieties that are well
adapted to your climate and site. Use the Plant Hardiness Zone Map deve-
loped by the U.S. Department of Agriculture (see page 21 ➔ ) to identify the
average minimum temperature for your area. For extra security, consider se-
lecting varieties rated one or even two zones hardier than your site to ac-
count for unusually cold winters. We will use the USDA map in recommend-
ing fruit varieties.
Pest and disease considerations. In the ideal pome fruit climates of the
western United States and parts of western Canada, even disease-prone
varieties can be grown successfully by organic orchardists. In the more hu-
mid regions of North America, however, disease resistance is a critically im-
portant consideration for organic fruit growers. More than 260 species of
bacteria and fungi cause economically destructive diseases on apples. Many
of these or similar diseases also infect pear, quince, medlar, loquat, and may-
haw.
In North America, apple scab and fire blight are two of the most common
and destructive diseases of apples. Pear scab infects pears, but it is seldom
as devastating as apple scab is on apples. Pome fruits are also susceptible
to powdery mildew; cedar-apple, cedar-quince, and cedar-hawthorn rust; vir-
uses; and stem cankers. By selecting good varieties and employing effective
orchard management practices, you can minimize these problems. Chapter
10 ➔ goes into detail on major diseases found in your region and recom-
mendations on dealing with them.
Common insect pests on pome fruits include assorted mites, scales, aph-
ids, mealybugs, leaf rollers, fruitworms, thrips, leafhoppers, leaf miners, lygus
bugs, cutworms, and wood borers. Most of these pests will not be serious
problems in a well-managed organic orchard. By far the most serious pests
are plum curculio, apple maggot, and codling moth. In the not-distant past,
these pests made pome fruit production of any kind very difficult in some re-