People who come to our orchard are often interested in having a few apple trees of their own, and ask us advice about growing their own apples. We have put together some of the guidance we can offer.
- First off, you should know that apples are both disease and pest prone, so if you want eating-quality fruit, you will have to work at it. Lots of other fruits are far less difficult to raise, including berries, pears, peaches, etc. If you are planning to use most of your apples to make cider with just a few apples to eat, you may be able to pull that off with relatively little pest or disease control.
- Variety selection. If you are planting trees, we really recommend using scab resistant varieties. We rely on our most scab resistant varieties for the pick-your-own business because they reliably produce high-quality fruit. Our two main scab resistant varieties are Libertys and Jonafrees. Some of the very old varieties, those grown prior to the introduction of fungicides, can also produce good fruit. The common apples grown in orchards in the 20th century, including MacIntosh, Golden and Red Delicious, and Cortland all require fungicides to get decent quality fruit.
- Planting. Be sure you know how much space your tree will take up, which depends on the size rootstock – dwarf trees can be placed closer together than standard varieties since their roots are smaller. Also think about good air drainage. Blossoms frequently get frosted off in locations where cold settles, like in a little hollow at the bottom of a slope, so if you have options on a slope, plant there. North facing slopes may be ideal, since the trees will delay flowering, and therefore frost damage on blossoms will be less likely. Prepare a good-sized hole, but you are probably best off top-dressing your new tree with compost rather than using lots of nitrogen in the planting hole. Concentrate on reducing root competition for your new tree, by mulching or companion planting. Good companion plants may have deep taproots to minimize root competition, or offer flowers for pollinators, and some herbs are repellant to apple pests. The Fedco tree catalog has an interesting piece on this type of planting, and recommends specific understory companions. Also be sure that your soil is the right pH - low pH soils, very common around here, can make it hard for your trees.
- Pruning/training. As the tree grows, you will need to train and prune it to maximize air flow through the tree, and space between branches so you can pick apples. You should get a book to help you with this, and/or find someone to teach you pruning. Ideally, trees should be pruned in late winter.
- Managing insect pests. There are a number of insect pests that can damage your apples, which may or may not occur in your area. You can use sticky traps to monitor for most pests, or just watch your apples for damage. Sanitation, that is picking up every fruit that falls to the ground, is an important component in reducing damage from all of these insect pests. You will need to use another resource to understand about degree-days and the seasonality of pests. One option is Cornell’s apple growing resource, newa.cornell.edu. We list our top five pests here.
- Plum Curculio (PC). This insect lays eggs on the fruitlets, and damages fruit for about a month from petal fall until a specific degree-day cutoff. The best current method to control this pest is to keep your trees covered with Surround, a refined kaolin clay you spray on the trees, for the period that PC is active.
- Codling moth (CM). This moth lays its eggs at the base of the apple, and the caterpillar crawls inside the apple where it tunnels around, eating until it leaves the apple and pupates. CM is active for a very long period, having multiple generations per year starting in July. Again, degree-days are used to track the life cycle of this insect. Early damage causes the fruitlets to fall off the tree, but late-season damage gives you the archetypal wormy apple when the apple is ripe. We are still working on controlling this pest, since we have unmanaged apple trees nearby, so sanitation or other in-orchard methods are not sufficient. Options include sprays of granulosis virus (Cyd-X), release of parasitic wasps, and reproductive suppression using pheromones. The last option works best in a large orchard, with few to no unmanaged apples in the neighborhood. In Europe, people use well-timed trunk sprays with entomopathogenic nematodes to kill larvae. This requires sufficiently warm temperatures and extended dampness in the fall, which doesn't happen every year.
- Apple maggot fly (AMF). This fly lays eggs on fruit later in the season, and the larvae tunnel throughout the fruit. The only way we have found to control this pest is orchard sanitation. Picking up all apples that drop at least twice a week will keep the larvae from reaching the soil and hatching the following year. Spraying Surround during the July-August AMF season is supposed to help, but will leave your apples covered with clay for harvest. There is some evidence that entomopathogenic nematodes target these ground-dwelling larvae, so we are trying this method.
- Apple borer. This is another moth that lays eggs on sapling apple trees, but the target in this case is the wood. Eggs are laid very close to the ground, and the caterpillar eats its way into the tree. It then tunnels through the tree, and eventually the tree breaks off due to the giant holes inside the tree. These are devastating to young trees. We spray entomopathogenic nematodes (species Steinernema feltiae) on trunks of young trees in the spring; research suggests 80% mortality of borers with this tool. The traditional way to fight this pest is to keep anything from growing near the trunk, so both you and potential predators can see the trunk and keep an eye out for damage. Once the caterpillars are inside the trunk, your only option is to poke a wire into tunnels, in the hopes that you will kill the caterpillar. Apparently the nematodes can move into the tunnels and kill the borer even once it has entered the tree.
- Voles. While you need the trunks open and visible all summer, you have to protect young trees from voles in the winter. We use the white plastic wraps or wire mesh cages around all young trees, placing them in the fall after harvest, and removing them in spring after the snow melts. Voles eat the bark and cambium off the trunk, girdling the tree so it dies. This was the cause of death for many trees in our orchard during the period when it wasn’t being taken care of.
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- Disease. If you choose varieties that don’t require fungicides for scab control, you only need to keep an eye out for less common infections, like frog-eye leaf spot, cedar rust disease, and the bacterial disease fire blight. For all fungal or bacterial infections, good pruning will allow the tree to dry out and protect itself as much as possible. If you need to control scab, we spray sulfur on susceptible trees during wetting periods in the spring when scab spores are likely out and active. Again, Cornell’s NEWA site lists wetting periods and scab activity.
- Thinning. Once you have fruit on the trees, you need to thin the apples in July. This serves several purposes: keep any fruit from touching, since insect pests burrow in wherever apples touch each other; keep the tree from producing too much fruit, which can cause it to crop lightly the next year; and hand-thinning is a good opportunity to pick off fruit with insect larvae inside. A rule of thumb is one apple every 5-8 inches, with all thinned fruit going into buckets so insect larvae can’t pupate and complete their life cycle.
- Fertilizing. At the end of the season, after apples are picked, we spread compost in the orchard. Trees will grow roots to wherever there are resources, so no need to spread the compost out. We throw a few piles within the drip line of each tree. Ramial wood chips are good too, or composted wood chips. Something to replace the nutrients you harvested in your apples will keep your tree going.