Tuesday, December 6, 2011

Growing Apples

Apples are the most popular tree fruit in North America. They're flavorful, healthful, and rewarding to grow, so it's no wonder that backyard gardeners want to include them in their landscapes. Happily, apples can be grown in practically every region of the United States. Successful growing depends upon several important factors that the gardener must carefully consider. These include appropriate varieties, space limitations, site considerations, soil, moisture, proper planting, pruning, pest and disease control.

You wouldn't know it by checking out the produce sections of supermarkets, but there are hundreds (maybe thousands) of apple varieties. In fact, every time an apple seed germinates, a new variety has potentially emerged. They range from "heirloom" varieties to the newest releases. Though the enthusiastic gardener might spend hours planning his orchard, sampling varieties, and poring over catalogs, he should know that the selection will be limited by his climate. The best way to determine which ones are appropriate is to consult with a specialist at the nearest Cooperative Extension Service office. Another method is to seek out fellow fruit growers in your area for their recommendations. If you live in an apple-growing region, there shouldn't be any shortage of advice. However, if you garden where apples are seldom grown, getting recommendations might be difficult.

Over twenty years ago, I explored the possibility of planting a small apple orchard in south Georgia. There were no fruit specialists at my nearest Extension Service office. (If I wanted to raise hogs or grow soybeans, I would've been in luck.) I could find no successful apple grower nearby, though I did locate a you-pick orchard in north-central Florida, of all places. I visited the owner, corresponded for awhile, and decided that I could grow them as well.

To choose appropriate varieties, I determined the average number of "chilling hours" for my area. Most states publish such data specific to their various zip codes. In lieu of good advice from local growers or specialists, the best I could do was to study possible varieties for their chilling requirements, and match them to my area.

A chilling hour is one hour that a fruit tree experiences after it goes into dormancy during which the temperature falls below 45 degrees Fahrenheit. Apple varieties have different chilling hours. When a variety has experienced a sufficient number of chilling hours, it is ready to flower. If it hasn't experienced enough, it won't flower. A variety with few chilling hour requirements may start to bloom as soon as it experiences a few warm days in a row. It can be devastating if a tree blooms during unseasonably warm weather with freezing temperatures afterward. On the other hand, fruit won't be set on trees that haven't received enough chilling hours.

The next step in choosing appropriate varieties is selecting those that bloom at the same time. This is necessary for good cross-pollination because apples are usually not self-fruitful. There are a few exceptions, but even those will set better crops if cross-pollinated.

The final step in choosing appropriate varieties is selecting those that you like or that meet your needs. You could purchase several different varieties from a grocer or farmers market to taste-test, but if they won't produce well in your area that won't help much. A few orchards sell customized packages from a large selection of varieties.

Backyard fruit growers are usually faced with space limitations. Since standard size apple trees can reach a height of about 20 feet, and spread nearly as much, the average gardener might be limited to a very few trees. But dwarf apple trees are commercially available. They're not just novelties; most commercial orchards grow dwarf ones. Here's how it works.

All named, commercially available varieties of apple trees consist of two parts, the rootstock and scion. The scion is clipped from a named variety, and grafted onto the rootstock. The rootstock may be produced from a non-descript seedling, in which case it will produce a standard size tree. (This is very interesting, but I can't deal with it now. Maybe later.) The rootstock may also be produced vegetatively from dwarfing stock. (You may wonder what "produced vegetatively" means. I'll also deal with that later.) The dwarfing rootstock will control the growth of the scion. In other words, two scions can be taken from a single apple tree, grafted onto different rootstocks, and different size apple trees will be produced. Dwarfing rootstocks do not effect the size and quality of the fruit.

Dwarf apple rootstocks were discovered by the ancients who probably observed them randomly occurring. During the last century, horticulturists began sorting out and naming dwarf rootstocks that had been available for centuries. Then they identified those that were virus free and insect resistant. These became the foundation for modern dwarfing rootstocks.

There are several dwarfing rootstocks commercially available. Some have only a slight dwarfing effect, producing trees about 18 feet tall. Some have an extreme dwarfing effect, producing trees as small as 6 feet tall. There are others that produce trees of intermediate sizes. Just as the rootstocks effect the size of the tree, they also reduce the time before the tree begins to bear fruit. While a tree on seedling rootstock may take as many as 10 years to bear, a tree on extreme dwarfing rootstock may bear in as few as 2 years.

Dwarfing rootstocks can have their disadvantages. Some of the smallest ones have very poor anchorage, so must be staked or similarly supported for the life of the tree. A typical tree stake might be a 2-inch by 2-inch wooden post or a 1-inch metal rod, 10 feet long, driven 2 feet into the ground about 6 inches from the base of the tree. I advise you to install the stake at tree-planting time to avoid damaging roots. Use plastic tape or adjustable plastic ties to secure trees to the stakes.

For a more complete discussion of dwarf apple rootstocks, I recommend you visit the Orange Pippin website. You'll find there are dwarf apple rootstocks available that will allow the backyard fruit grower to raise quite a few varieties in very limited space.

When choosing a site for apple trees, select one that is not in a "frost pocket." A frost pocket is where cold air collects. Cold air from a late frost will certainly destroy blossoms and fruit if allowed to collect around the trees. Cold air runs downhill like water and collects in low-lying areas, so avoid them. The site should allow cold air to drain away from the trees.

Select a site in full sun away from large trees and structures that cast shade.

Adequate soil moisture is important, but apple trees don't swim. Water should drain completely within an hour of a hard rain.

Before I planted my orchard, I requested a soil specialist to take a core sample of the site. He found the water table on the lower end of the area to be 3 feet from the surface. "Not a problem," he said. He was wrong. So I recommend that the water table should never be within 4 feet of the tree roots, for the roots will not grow into the water. In other words, if you can hit water within 4 feet of the surface, find another site. A high water table will effectively prune the roots, and will create an unhealthy environment for the tree.

Take a soil sample of the site to your nearest Cooperative Extension Service office for analysis a couple of months before planting time.  Proper soil pH should be between 6.5 and 7.0. Follow the recommendations, incorporating soil amendments at least 12 inches into the soil.

Tree spacing differs according to the rootstock. Refer again to the Orange Pippin website for recommendations. Prepare sites 6 feet in diameter by eliminating weeds with a glyphosate herbicide. Follow label instructions. After weeds are dead, cultivate 10 to 12 inches deep, incorporating the soil amendments. Allow weed seeds to germinate, then spray again with glyphosate. Let the new weeds die.

If purchasing bare-root stock, choose healthy 1-year old trees 4 to 6 feet tall. Carefully inspect the roots. If you see nodules in the roots, don't buy it. The nodules probably indicate the presence of wooly apple aphids. Do not purchase trees that have abrasions, lesions or strange lumps along the stem or on the branches.

Container-grown plants may be available year-around. If you can obtain them in fall, I recommend planting then. Though there will be no shoot growth until spring, the roots will establish themselves over winter, giving a head start for the growing season. Bare root plants should be more economical, but are seldom available until spring.

If you're unable to plant your bare-root trees upon receiving them, dig a trench and place the roots in it. Then cover the roots with soil or some other organic medium. This procedure is called "heeling-in." Water the trees immediately, and maintain moisture around the roots. If the roots appear to be dry upon receipt, soak them in water overnight, then heel-in.

Plant the trees in spring in the center of the sites. The graft union, an obvious bend in the trunk a little above the roots, should be set 2 inches above the surrounding soil line. Add water to the planting hole as the soil is being back-filled.

I must mention at this point that extreme dwarf apple trees can be effectively grown in large containers as outdoor potted plants. If this is your plan, you must still consider the potential for frost pockets, sun exposure, and the need for soil analysis to ensure proper pH and nutrient levels. Of course, if they're growing in pots, you can move them about at will.

Proper training of apple trees is essential to the development of strong limb scaffolds to produce and support high-quality crops. Not only should the limbs be able to bear the weight of the crops, but must also allow good light penetration and air circulation. It's vital to begin training the trees from the beginning while they're supple.

The "central leader" form is probably the most popular. It has one central, upright trunk called a "leader." There are other forms, some of which I'll discuss in a future article. But, here's how to begin training the tree to this form.

At planting time, or before new growth begins, prune the young tree (called a "whip") to about 36 inches high. Cut a little above a side bud at a slight angle sloping downward away from the bud. The lower end of the cut should be above the bud on the opposite side of the trunk or "whip." Winter or early spring pruning will stimulate new growth below the cut when weather warms. Allow that top bud to sprout and grow vertically. If it looks like it won't grow vertically, encourage it a little. I used little pieces of pliable aluminum roof flashing. I formed each into something resembling a spoon with side flaps, loosely placed the spoon in front of the emerging sprout, wrapped the flaps around the whip and taped them in place. (Be careful to file off sharp edges. Don't cut yourself.) The sprout would bump into the spoon, and be turned upward. (The training spoons will have to be removed after they've served their purposes.)

In addition to the vertical sprout at top, others will form below. The trunk should be kept free of branches to a height of 24 to 36 inches above the soil surface. The first level of branches should include 3 or 4 that emerge from the trunk evenly spaced in a whorl.

Left alone, the branches will probably emerge at a 45 degree angle or less. Such an angle makes for a weak scaffold unable to bear a load. I'll explain why.

If a limb is allowed to grow at a narrow angle, tree bark in the crotch of the limb will be "included" as the wood around it grows and the limb thickens. This inclusion is never out-grown; it is only over-grown, and the inclusion forbids strong healthy wood from forming, except below it. You might as well drive a metal plate into the crotch; no supporting wood will grow in the crotch, and the little bit of healthy wood beneath the inclusion will never be strong enough to support a crop load. This, by the way, is why trees with tight crotches such as ornamental Bradford pears (Pyrus calleryana) are so prone to splitting.

A better crotch angle approaches 90 degrees. "Spacers" are available commercially. I made mine from strips of wooden lath, cut to varying lengths, with V-shaped notches cut out at each end. These I placed between the trunks and limbs to spread the branches downward. I've also used little sandbags, placing them on the scaffold limbs to weight them into the proper position. A sandbag has the advantage of being moveable so that it can be re-positioned outward along the branch as it grows.

Continuing the training, the vertical tree trunk is kept bare of emerging branches for another 20 inches before a second "scaffold whorl" is allowed to form. This space will allow better light penetration and air circulation between scaffolds. And so it goes up the tree for the life of the tree. Annual winter pruning of the central leader will promote good scaffold development.

Upright branches that can't be trained to more horizontal positions should be removed during summer. You'll notice that vigorous re-growth will not follow summer pruning, so those incorrigible branches that won't be trained horizontally will not be replaced when removed.

Proper nutrition is essential for good fruit production. I recommend taking a soil sample for analysis annually at the same time of year to ensure that the readings are consistent. Believe it or not, the results can vary according to season.

When applying fertilizer, always disburse it around the "drip line" of the tree. That's where the feeder roots are. The drip line is the under the perimeter of the tree canopy. It will do no good to apply fertilizer near the trunk. Synthetic fertilizer should always be applied at least 6 inches from the trunks of young trees.

Keep weeds and grass from under the tree. They create too much competition for available nutrients and moisture. Don't roto-till as it might disturb roots. Never operate a string-trimmer anywhere near the tree trunk; the flying string will girdle it. The best method is to use a herbicide labeled for apple orchard use. Yes, there are organic methods of weed control, such as mulching. However, they also have their disadvantages. I'll save that for a future article.

Insects and diseases can ruin your trees and fruit. The foundation of any pest control regimen is a clean orchard. Diseased wood should be pruned out. Debris such as fallen leaves and fruit should be removed and composted for use elsewhere in your garden. Pruning tools should be disinfected with a dilute, 10% solution of bleach. Alcohol is also effective.

Still, insect and fungus control will be necessary. First, note that there are organic pest control methods that are worth using. However, it's beyond the scope of this particular article to discuss them.

Begin with an early spring application of "dormant oil" as soon as leaf buds begin to swell. Dormant oil will smother scale insects and eggs. Follow up with periodic fungicide and insecticide applications. Some manufacturers produce "all-in-one" formulations. Because there are quite a few products on the market, it's best for you to choose one labeled for apple trees, and follow label instructions. By the way, when using herbicides, pesticides and fungicides, always follow label instructions and wear appropriate protective gear.

Don't forget that apples are pollinated by bees. Insecticides are not particular about which insects they kill, so take care not to apply them during the bloom period when bees are busy.

You may be so successful that you're rewarded with an extremely heavy crop. Actually, that's not a good thing. An over-abundance can break limbs, reduce fruit size and inhibit bearing the next year. Thinning some of the fruit may be necessary. If it appears that you have a heavy fruit set, remove some of the little green apples when they are about 1 inch in diameter. You may find as many as 6 growing in a cluster. Nip all but one in the bud. Leave one small apple per cluster, and allow 6 inches between fruits. Doing so may seem counter-intuitive, but thin them anyway.

When you begin to harvest your own, home-grown apples, you'll be proud of yourself. I'm convinced that apples taste better when they come from your own backyard.

John J Marshall

John also blogs at goGardenNow.blogspot.com.

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