Apple Trees

Apples are the most widely planted tree fruit in Wisconsin ¹. A couple of well-chosen dwarf trees will feed a family fresh fruit from August into winter. The decisions that matter most are made before the tree goes in the ground: which rootstock, which varieties, and where.

Rootstock sets the size

A nursery apple tree is two plants joined together. The rootstock below ground decides how big the tree gets; the scion above it is the variety that makes the fruit ¹.

• Dwarf (M.9, M.26): 8–10 ft tall, about 75–100 ft² each. A few fruit in the third year. Nearly all the work can be done from the ground, without a ladder.
• Semi-dwarf: 10–20 ft, 125–200 ft² each.
• Standard: 300–400 ft² or more and possibly over 30 ft tall. Fruit in 5–7 years.

Extension recommends dwarfs for home gardens: several small trees give more fruit over a longer season than one big one, and they’re easier to prune, spray, and pick ¹. Buy from a nursery that tells you the rootstock ¹. One caution: M.9 and M.26 are very susceptible to fire blight, so variety choice and not overfeeding nitrogen matter more on them ¹. Dwarfs also root shallowly, so they’re usually staked or trellised.

Site

From A3565 ¹:

• A gentle slope, so cold air drains away on frosty spring nights. Valley bottoms are frost pockets, several degrees colder than nearby slopes, and they kill blossoms. Hilltops are too windy.
• Drainage. Apples won’t tolerate wet feet.
• pH 6–7. Soil test the season before you plant and lime or sulfur as the test says.
• Full sun at least three-quarters of the day.
• No grass within 18 inches of the trunk, and a 2–3 ft clear circle is better. Grass competes hard for water and nitrogen.

Planting

Dig a hole wide enough to spread the roots without bending them. Set the tree so the graft union, the knob where scion meets rootstock, is 2–3 inches above the final soil level ¹. If it ends up buried, the scion grows its own roots and the tree loses its dwarfing. Backfill with the soil you dug out, firm it with your foot, and water. Don’t put fertilizer or manure in the hole ¹.

If you planted an unbranched whip, cut the top off at 30–45 inches. New branches sprout just below the cut, so the height of the cut sets the height of the first limbs ¹.

Two varieties

Apple blossoms are self-unfruitful: pollen from the same variety won’t set fruit. Bees have to bring pollen from a different variety that blooms at the same time ¹. A crabapple in bloom nearby works for any apple ². A few varieties, such as Jonagold, are triploid and make poor pollen, so they need two other varieties around them ².

Picking varieties

Two rules come first: the variety has to be hardy where you live, and it has to ripen by mid-October ¹. Most of Wisconsin is zones 4 and 5; much of the north is zone 3, where only the hardiest apples survive ². Fuji and Granny Smith need about 180 days from bloom and won’t mature here ¹.

The third rule is scab resistance. Apple scab is the most serious apple disease in Wisconsin, and resistant varieties skip most of the fungicide sprays ¹. From A2105’s table ²:

Choosing one early, one mid, and one late variety spreads the harvest from late August into October; check with the nursery that their bloom times overlap so they can pollinate each other.

Pruning

Train a young tree to a central leader, one main trunk with tiers of side branches (scaffolds) growing out at wide angles, which are the strongest ¹. Keep the lowest scaffold at least 24 inches up and the top of the tree narrower than the bottom, so every leaf gets sun. Leaves in shade can’t make the sugar that good fruit needs ¹.

Each year ¹:

• March and April, while dormant, is the time for major pruning.
• Remove dead, broken, and crossing branches, downward-growing limbs, and straight-up water sprouts. Upright shoots make leaves, not fruit; flatter branches fruit.
• Prefer thinning cuts (removing a whole branch at its origin) to heading cuts.
• A light pruning in late July to early August can remove water sprouts and open a dense canopy. Nothing after early August: it delays dormancy and invites winter injury.

Pests

Even scab-resistant trees still need insect control ². The big one is the apple maggot (“railroad worm”), a fly that lays eggs in fruit from early July until harvest; its larvae tunnel through the apple. Uncontrolled, it’s the worst apple insect in Wisconsin ¹. Hang red sticky spheres (with an apple-scent lure) in the trees to see when the flies are active and, on a few trees, to catch many of them. Codling moth, plum curculio, and leafrollers are the others to learn ¹.

Try it

Before ordering trees, walk your land on a still, frosty morning and note where frost lies longest. Pick a sunny, gently sloping spot above it, soil test it this fall, and order two or three scab-resistant dwarfs that bloom together and ripen by early October.