Dorothy is a Master Gardener, former newspaper reporter, and the author of several books. Michael is a landscape/nature photographer in NM.
Problem 1: Lack of a Second Apple Tree for Pollination
Apples are my favorite fruit, and I eat at least one or two every day—but I buy mine at the supermarket. I used to have an apple tree in my backyard when I lived in Arkansas, but the apples were never fit to eat. I didn't know at that time that I needed two different apple trees for pollination. Apple trees need another tree nearby for pollination, and it can't be one of the same variety. You need to have a different variety of the same fruit! Who knew? Not me, unfortunately.
Since that time, I studied apples and researched every potential problem I could come up with. Hopefully, some of the things I have learned will come in handy for you if you want to raise your own apples in your own backyard.
The following are some of the problems you might have, as well as solutions to those problems.
Problem 2: Apple Maggots
If your apples have brown, indented spots (called dimpling) on them and/or narrow brown tunnels (called tunneling), you probably have some apple maggots that have taken up residence in your fruit. Apple maggots are also known as railroad worms and they are the larvae of a small fly. In the winter, they mature in the soil, emerging in the early summer months all the way through fall. The females will lay single eggs under the skin of the fruit. Once they get in the apples, they are immune to pesticides.
The apple maggot fly has a black abdomen and is only about a quarter of an inch long. The females have four white bands on the abdomen, while the males are smaller with only three bands. The wings of the fly are clear but marked with black bands.
- Pick up any apples that have fallen off the tree as soon as possible, as they may contain maggots.
- No later than about mid-June, hang some red sticky traps at eye level and a few feet inside the tree canopy. If you are growing a dwarf tree, you probably will only need one, but for a standard-size apple tree, you will need to hang several of them, cleaning and replacing the sticky coating about twice a week.
- You can spray your tree with a synthetic insecticide if it contains carbaryl, methoxychlor, or a mixture of carbaryl and malathion. If you choose this method, spray approximately 7-20 days from the end of June up until early fall (September). Make sure you are selecting a formulation that is registered specifically for apples.
Problem 3: Cedar-Apple Rust
Cedar-apple rust causes galls (growths) to form on certain apple species but the rust does not originate on apple trees. It is a fungal disease that infects eastern red cedar trees (Juniperus virginiana) on needles and small twigs. In order to survive, the fungus has to move from one type of host to another (such as from juniper to crabapple). The spores infect apple or crabapple trees for a full year as the life cycle of the fungus completes. When mature, the growths will swell considerably, producing orange, gelatinous telial horns (one of the stages in the life cycle of a parasitic heteroecious fungus).
In the spring, the leaves and apples develop small yellow spots that will turn orange, then darken taking on a sunken appearance. The leaves will likely fall and the fruit will be small and misshapen.
- Rake up and remove any fallen apples or leaves, removing them completely from the area.
- If you have juniper trees, pick the galls from them in late winter, before the orange telial horns emerge.
- Place any ornamental junipers at least a few hundred yards away from any apple trees, and select only apple varieties that are resistant to cedar-apple rust, such as Dayton, Liberty, Macfree, Nova Easygro, Priscilla, Redfree or Williams Pride. Although the spores can be carried several miles, most infections occur within a few hundred feet from the source tree.
- Spray your apple trees with a synthetic fungicide containing any of these active ingredients: mancozeb, maneb, or triflumizole. Apply the spray in the spring when the flower buds are showing pink, and again when most of the petals have fallen. Then, approximately 10 days to two weeks later, apply the spray again.
- Only select a fungicide formulation that is registered for apples.
Problem 4: Lack of Good Color on Apples
If your apples stay green rather than developing the correct color for whichever variety you have planted, you are probably failing to prune the tree(s) properly. Apples need sufficient sunlight to ripen and color properly.
- Plant your apple trees in an area that receives full sunlight most of the day.
- Thin out the interior branches. The correct pruning method for most apple trees is called the modified leader, the leader being the main stem of the tree. When your tree grows to about 10 feet high, cut the leader back a few feet. For the first few years that your tree bears fruit, pick some but let some remain on the tree. The weight of the apples will strengthen the side branches, helping them to grow perpendicular to the tree trunk.
Problem 5: Apple Aphids
There are two different species of aphids you might find damaging your apples - the apple aphid and the rosy apple aphid, both of which will cause leaf curl. They are teardrop-shaped insects that will show up on stem tips, leaves, and buds. The affected leaves are often twisted, and the stem tips become curved. Leaves will become sticky and/or blackened. The apple aphid is green and the rosy apple aphid is a pinkish-rose color.
The most severe leaf curl is caused by the rosy apple aphid. Both species, however, overwinter on apple bark. The rosy apple aphid will be gone by mid-summer but the apple aphid will continue feeding on your plants through summer.
These aphids secrete honeydew, a partially-digested sap that will attract a dark gray fungus called sooty mold.
- Dispose of the infested stems by pruning your trees. If stems are crowded, thin out the dense inner growth to increase air circulation.
- For a more severe outbreak, spray your tree with insecticidal soap or neem, a botanical insecticide. You could also use a synthetic insecticide containing one of the following active ingredients: malathion, carbaryl, or endosulfan. Don't allow the spray to get into the curled leaves, and always select a formulation registered for apples.
- To discourage aphids, spray your tree in the spring with dormant oil as the leaf buds begin to swell but before they start turning green. Dormant oil consists of refined petroleum oil that will smother overwintering insects like aphids and their eggs, but to be effective it must come in contact with the pests. It can also be applied in the winter months when fruit trees are in their inactive period.
Problem 6: Apple Scab
Apple scab is a fungal disease. It manifests as dull black or grey-brown lesions on the surface of the buds, leaves or fruit. The fruit may also be misshapen and the leaves can also develop spots and fall off the tree. The spores of apple scab are carried by the wind, and they can overwinter in the fallen leaves and fruit. When spring weather is mild and damp, the disease becomes even more severe.
Scabby spots on the fruit are sunken and tan and may have velvet-like spores in the center. As the spots mature, they become larger and turn brown and cork-like. The infected fruit becomes distorted and can crack, which allows secondary organisms to gain entry into the fruit. If your apples are severely affected, they may drop, especially when young.
- Completely remove all the fruit and leaves that have fallen by the end of the season.
- Spray your infected trees with lime sulfur, an organic fungicide, when the buds first begin to show green.
- On humid days when the temperatures are above 60 degrees Fahrenheit, spray expanded leaves with sulfur and repeat weekly or after each rainy day. Continue until the middle of the summer or until the scab diminishes.
- Spread a thick layer of organic mulch (4-6 inches) beneath the trees in late fall to keep any spore-laden soil from splashing up onto the tree. Be careful, however, to keep the mulch at least six inches away from the tree's trunk to allow air to circulate around it. Compost makes a great mulch.
- Prune your trees in late winter to promote adequate air circulation.
This content is accurate and true to the best of the author’s knowledge and is not meant to substitute for formal and individualized advice from a qualified professional.
© 2019 Mike and Dorothy McKenney