Growing high-quality apples in the home garden is possible but requires significant inputs. Apples have several serious disease and insect pests that can significantly lower the quantity and quality of the apple harvest in the fall. Managing these disease and insect pests is important, and many of the most effective management steps occur in spring, well before the apples form and ripen.
Overall Approach | Spray Schedule | Organic Options | Home Orchard Sprays |Nonorganic Options | More Information
An Integrated Approach
There are many approaches a home gardener can take to address the issues that can affect apple trees. Relying on one alone will not yield high-quality results. An integrated approach that utilizes multiple strategies to address common insect and disease issues will produce the best results.
Good Care & Management
An integrated approach that starts with good care and management is important. Good sanitation and clean-up of fallen fruit and leaves help eliminate potential inoculum and overwintering eggs and larva that could infect trees the following year. Reduce weeds surrounding trees to eliminate pest breeding, feeding, and overwintering sites.
Good pruning removes diseased wood and promotes airflow through the canopy, which reduces insect and disease-causing organisms from building in population.
Good care and selection by planting disease-resistant cultivars, mulching the base of trees, planting in appropriate soil conditions (moist, well-drained), and watering trees during dry periods, particularly when they are young, all help produce high-quality apples.
Traps
Sticky traps are available from garden catalogs and stores. Insects are attracted to these devices and trapped, making them helpful in monitoring a pest insect's presence and population size. Traps are also occasionally used with the hope of eliminating the insect before they have a chance to damage the apples. Some traps, such as those for codling moths, are sticky cards inside small tents and often include a pheromone lure. Other traps, such as those for apple maggot flies, are red spheres or yellow cards utilizing the color and shape to lure the pest.
Traps are more effective for monitoring pest population size rather than controlling the pest population and they are best used to determine if and when a spray is needed. For apple maggot, research has indicated that the high number of 1 trap for every 100 fruits on the tree may provide satisfactory levels of control.
Spray Schedule for Apples
Good culture practices and sanitation may not be enough, and apple trees may need to be sprayed to prevent common insect pests like apple maggot and coddling moth and common diseases like apple scab, powdery mildew, cedar apple rust, and fire blight.
Applying the Spray
Whenever sprays are applied, it is important to follow label directions. The most effective control comes from applying the product as directed. Nearly all spray treatments will require multiple applications spaced throughout the growing season. The interval between spray applications should be strictly followed.
When applying the spray, utilize a pump sprayer and thoroughly cover all the foliage and branches. Never mix more spray material than needed for that application and always store chemicals in their original containers.
When applying the spray, wear appropriate personal protective equipment as outlined on the label. This usually includes long sleeves and pants, goggles, and chemical-resistant gloves. Always apply chemicals when winds are calm (less than 10 mph), temperatures are cool but above freezing, and no rain is forecasted for at least six hours. More details on appropriate weather conditions for specific chemicals are listed on the label.
Timing of the Spray & Developmental Stages
The timing of the application is important as many insect pests are more susceptible to sprays at certain points in their life cycle, and most diseases are best controlled preventively before the symptoms are observed. Often the product label will direct the home gardener to spray at certain developmental stages in the tree’s annual growth cycle. The precise time of year these stages are observed will vary year to year by location, climate, and weather conditions.
Developmental Stages of Apple
Below are the key developmental stages to know and what those stages look like on an apple tree.
Stage | What it Looks Like | Insects & Diseases Often Controlled at this Stage | |
|---|---|---|---|
Dormant | Buds are small and tight, no signs of growth | scale, aphids, spider mites | |
| Silver Tip | Buds swell and turn fuzzy silver from emerging leaves | aphids, scale, mites, apple scab |
| Green Tip | Green leaves begin to emerge from the tips of buds | apple scab |
| Half-inch Green (Mouse Ears) | One half-inch of leaves are visible, folding backward as they emerge, resembling small mouse ears | apple scab |
| Tight Cluster | Young apple leaves have emerged and are folded backward, revealing a tight flower cluster | apple scab, powdery mildew |
| Pink Bud | Flower buds have grown to reveal pink petal color but still not open | apple scab, powdery mildew, plum curculio, apple sawfly |
| First (King) Bloom | The center (or king) bloom opens first, before the buds that surround it | apple scab, powdery mildew |
Full Bloom | At least 80% of the flowers are open | apple scab, powdery mildew, cedar apple rust | |
Petal Fall | Petals are raining down from trees, carpeting the ground | apple scab, powdery mildew, cedar apple rust, plum curculio, apple sawfly | |
Fruit Set | Young fruit is visible | apple scab, powdery mildew, plum curculio, apple sawfly |
Photos by Suzanne Slack
Protecting Pollinators
Most insecticides are toxic to all insects, including important pollinators like bees. Insecticides, both organic and synthetic, applied while bees are active (such as during full bloom) can negatively impact these beneficial insects. Avoid spraying plants when pollinators are visiting the tree. Use systemic insecticides with caution as the insecticide may be present in the pollen and nectar of the trees if growing in a treated area. The “Environmental Hazards” section of the insecticide label will outline the important precautions that should be taken when bees are present.
Organic Spray Schedule for Apple
This approach utilizes organic sprays to help control the most significant insect and disease issues, including apple maggot, codling moth, apple scab, and powdery mildew. It is one example of an approach that can be used. Additional control strategies may be needed. Always follow label directions on any chemical spray, even if it differs from what is listed below.
Stage | Spray |
Dormant | Dormant oil for scale and overwintering eggs of aphids and mites, control of some diseases |
| Silver Tip | Copper for fire blight |
Green Tip | Sulfur (must be three or more weeks from dormant oil) for disease prevention; insecticidal soap or neem oil for aphids and mites (if a problem) |
Pink Bud | Sulfur spray (not lime sulfur) for disease prevention; neem oil for aphids (if a problem); Bt or spinosad for pest caterpillars (do not mix with sulfur spray; apply separately) |
First Bloom | Do not use other insecticides at this time to avoid harm to beneficial pollinators such as bees |
Petal Fall | Repeat sulfur and Bt or spinosad and again 7-10 days later, if needed, or begin kaolin clay sprays for insect pest control |
| Fruit Set & Throughout Summer | Starting at this stage spray sulfur spray or potassium bicarbonate every 7-14 days when signs of disease are observed, stop 30 days before expected harvest; spray pyrethrum, spinosad, insecticidal soap, or neem when any insect pests are observed on the same schedule |
*Adapted from the Sample Organic Spray Schedule for Apples. Hill, Lewis and Leonard Perry.The Fruit Gardener’s Bible.2011. Storey Publishing, North Adams, MA. Page 134.
Home Orchard Sprays
For many home gardeners, a home orchard spray is the most straightforward management option. They are often the best place to start when you are looking to start a pest and disease management plan. These mixtures typically contain one or more insecticides, such as carbaryl, permethrin, or malathion, and one or more fungicides, typically captan or sulfur. They are formulated to control common apple pest insects and diseases such as apple maggot, coddling moth, apple scab, powdery mildew, and cedar apple rust. Always check the label to be sure they are safe to use on apples and control the insect or disease issues you have the most problems with.
Read the entire label and follow the spray schedule outlined on the label. For the best control, it is important to follow the directions closely applying the spray at the correct rate and time throughout the entire growing season.
Home orchard sprays greatly simplify the spraying process, but they have a few limitations. They can lead to applying a spray when one of the pesticides in the mix has no benefit to the crop. The result is that these pesticides are wasted and depending on when they are applied could cause problems for beneficial insects or pollinators. Always read the label carefully and thoroughly, and be sure to apply the home orchard spray when bees are not active, such as before or after the bloom period or at dawn or dusk when they are less active.
Nonorganic Spray Schedule for Apple
If you choose not to use a home orchard spray, then pesticides will have to be purchased and applied separately in accordance with eachproduct's label.
The spring spray schedule below utilizes “traditional” nonorganic sprays to help control most insect and disease issues. It is one example of an approach that can be used. Additional control strategies may be needed. Always follow label directions on any chemical spray, even if it differs from what is listed below.
Stage | Spray |
Dormant | Dormant oil for scale and overwintering eggs of aphids, mites; control of some diseases |
Green Tip | Mancozeb for rust (must be three or more weeks from dormant oil) |
Tight Cluster | Captan or mancozeb for scab and rust |
Pink Bud | Captan or mancozeb for scab; malathion for sawfly; Bt for pest caterpillars |
First Bloom | Captan or mancozeb for scab (do not use other insecticides at this time to avoid harm to beneficial pollinators such as bees) |
Petal Fall | Captan or mancozeb for scab; carbaryl, malathion, or indoxacarb for plum curculio |
Fruit Set & Throughout Summer | Carbaryl, malathion, or indoxacarb for plum curculio; Starting at this stage, spray captan or sulfur every 10-14 days for scab, stop 30 days before expected harvest; spray carbaryl, malathion, indoxacarb, acetamiprid, or spinetoram for apple maggot and codling moth on the same schedule. |
Summer Sprays
While preventative sprays applied in the spring can help control many issues in apples, some insect and disease pests require two or more sprays throughout the summer months. Starting at fruit set, they are typically spaced every 10 to 14 days for the remainder of the growing season. Discontinue all spraying four weeks before harvest or according to the label directions.
More Information
- Organic Apple Production in Iowa (pub)
- Apple IPM for Beginners – Cornell University
Insects
- Apple Maggot
- Codling Moth
- Japanese Beetle
Diseases
- Apple Scab
- Cedar Apple Rust
- Sooty Blotch and Flyspeck on Apple
- Fire Blight
- Apple Bitter Rot
- Controlling Physiological Disorders of Apple Fruit
More Information on Growing Apples
- Growing Fruit in Iowa (pub)
- Tree Fruit Pollination (pub)
- Fruit Cultivars for Iowa (pub)
- Pruning and Training Fruit Trees (pub)
- Harvesting and Storing Apples (pub)
- Why Fruit Trees Fail to Bear (pub)
