Bugs on Apple tree

Keeping Pests Out Of Apple Trees: Common Insect Pests Affecting Apples

As much as we love apples, there is another species which out-rivals our delight in this fruit — a wide array of insect pests affecting apple harvests. What then are some apple tree bug treatments that will assist us with keeping pests out of apple trees? Read on to learn more.

Pests of Apples

To properly devise a plan of attack against these marauders, we must first identify what they are. Unfortunately, there are numerous pests of apples just a few of which are:

  • Round headed apple tree borer
  • Apple maggot
  • Codling moth
  • Plum curculio
  • San Jose scale

And then there are secondary pests like:

  • European red mites
  • Red banded and oblique banded leafrollers
  • Rosy apple aphids
  • Green fruitworms
  • Leafhoppers
  • Japanese beetles
  • Wooly apple aphids

Everyone loves an apple! Unlike some crop pests, insect pests of apples are not always immediately evident until it is too late and major damage has been done to the resulting harvest. To maintain healthy trees with optimal production, not only do you need to recognize what insects to look for, but also understand their biology and combine this knowledge with appropriate preventive measures and controls as needed.

Major Insect Pests Affecting Apples

There are quite a few pests listed above, but the big three most detrimental to the apple tree are: Apple maggot flies, plum curculio and codling moth. The best time to control these competitors is during mating season when they will be looking for egg laying sites early to midsummer on or near developing apples.

  • Apple maggot flies – Apple maggot flies lay eggs in developing fruit in June or July. Once the eggs hatch, the larvae burrow into the apples. Sticky traps can be hung in the tree near fruit about three weeks after petals fall; two traps for trees less than 8 feet tall, and six traps for those 10-25 feet tall. Trees can also be sprayed with Surround in July, or Entrust, which is pretty pricey. Entrust contains spinosad which can be found in some home use spray products, but keep in mind they contain other ingredients that will disqualify them as organic.
  • Plum curculio – Curculio is a ¼-inch long beetle that tunnels through apples, leaving a telltale crescent-shaped scar. You can kill adults by spraying with phosment right after petal fall and then again 10 days later. Do not spray when bees are active and wear protective clothing. Also, several applications of Pyganic (pyrethrum) post petal fall will reduce this beetle population. For non-chemical control, spread a tarp beneath the apple and shake to dislodge the beetles. Rake and destroy any dropped fruit to gradually reduce the infestation.
  • Codling moths – Codling moths hatch within days and the larvae tunnel into the apples to feed and mature, killing the fruit. To battle codling moths, spray with Bacillus thuringiensis kurstaki in the evening 15 days after petal drop and again five days later.

While there are a number of all purpose fruit sprays to combat apple tree pests, keep in mind that they often target beneficial insects as well. If you do choose an all purpose spray, do so after twilight when pollinators are not present. A chemical free option for thwarting harmful, dormant insects and eggs is to smother them with nontoxic horticultural oil in the spring prior to new leaf emergence.

How to Protect Apple Trees from Insects

Of course, there are some good insecticidal sprays out there that can assist with keeping pests out of apple trees, but there are also some simple cultural controls that will go a long way in solving the pest problem. Good pest management begins with good horticultural management. First and foremost is to maintain a weed free environment surrounding the apple trees.

Also, rake up last year’s leaves and detritus from around the base of the tree. Some pests overwinter in this cozy layer, waiting to assault the tender leaves and buds in the spring. Your goal is to eliminate any hiding places. Mow around the tree or, better yet, replace grass with mulch. Remove plastic and paper trees guards where adult moths and flies like to over winter, and replace them with wire mesh guards.

Prune the apple tree every winter prior to new growth. Cut out any crossing branches, water spouts, and generally over-crowded areas. The goal is to open the tree up to sunlight and provide adequate aeration. which will promote fruit set and tree health while reducing the incidence of fungal diseases and insect habitats.

How to Keep Bugs Away from Fruit Trees

Bugs are an important part of the ecosystem, and they play a crucial role in our gardens and yards. However, that doesn’t mean we want them on every one of our plants. In fact, bugs can sometimes do quite a bit of damage to the flora we work hard to cultivate.

A prime example of vulnerable greenery is homegrown fruit trees. Bugs love devouring fresh, ripe fruit on the branch. You might watch an apple grow gradually to perfection for a month, only to find it eaten from within before you get to enjoy it. Although there’s no perfect preventative method, there are some simple ways to keep bugs at bay, so you can reap the literal fruits of your labors.

Healthy Plants Keep Bugs Away

Your first line of defense in keeping fruit trees insect-free is to pick your plants with care. When purchasing your future snack provider from a nursery, check it carefully for bugs and insect eggs. Inspect the leaves and stems from all angles for bumps or discoloration, and gauge the thickness of the stems and color of the leaves to get a sense of the plant’s overall strength.

Grow Trees in the Right Conditions

Choose species native or well adapted to your region to give your fruiting friends their best chance at a healthy life. Then make sure you set them up for success with ideal growing conditions. Trees nurtured in fertile, well-drained soil will have the natural tools they need to resist pests. Trees that get little sun or the wrong amount of water will become more vulnerable to infestation.

Keep Trees Tidy

The better you maintain your fruit trees, the fewer insect invasions they will have to suffer. Always remove fallen fruits from the area around the base of your tree. Keep the nearby grass well trimmed, and rake any leaves or debris away to discourage creepy crawly communities from developing.

Use Chemical Sprays

Certain fruit trees require chemical sprays to keep harmful insects away. This may include occasional dormant oil spraying in the winter and more frequent treatments during the growing season. This approach takes consistent work, but the payoff can be significant, especially if you’re hoping to produce a high volume of fruit. These sprays are typically quite effective, if you have the time and energy to apply them. If you’re hesitant to bring chemicals into your yard, consider reaching for a homemade alternative.

Install Insect Blockers

Make it hard for bugs to get to the leaves and blooms of a tree by blocking their path. Copper bands around a tree trunk can provide a subtle electrical charge when snails or other insects attempt to pass.

Prune Your Tree Frequently

Well pruned fruit trees are less likely to be riddled with bugs and pests. Thin out the tree and cut superfluous branches, taking care to get rid of diseased or damaged limbs. It’s also important to prune away branches that cross over each other. This habit promotes healthy growth and improves air circulation through the tree, making it less welcoming to hungry invaders.

Welcome Birds to Your Garden

One of the best ways to naturally control your insect population is by inviting feathered friends to take up residence nearby, or at least making your yard a popular location for these avid bug consumers. World avian populations have declined sharply in recent years. Help reverse that trend by creating a safe space for them to enjoy. They’ll return the favor by gobbling up the competition for your carefully cultivated fruit.

A worm crawling out of a freshly picked apple is a classic image, but it’s not something most of us want to see in real life. Use the above-listed tips and you’ll harvest insect-free fruit all summer long.

How to Care for An Apple Tree

A few years ago, after buying our house—which we’re slowwwwwwwllllyyyy renovating, by the way—I looked out into the backyard from the kitchen window and noticed what appeared to be an apple tree fruiting!

I ran out and took pictures of the leaves and the budding fruit, as excited as you might be if you found $100 lying around your back yard. I sent them to others in search of answers. Soon enough, it was confirmed—I had an apple tree!

I immediately started dreaming of homemade applesauce, homemade apple butter, fresh apple pie…anything you can make with apples, really.

Just one problem: I had no idea how to care for an apple tree. I figured the fruit just gets bigger and then in the fall, you pick it. And that’s—well, that’s it, right?

Well, no. Not even close.

Apple Tree Care Tip #1: Thin Your Fruit

Around July, just a few months from harvest, I started noticing dark gray splotches developing on each and every fruit. My heart sank.

It turned out to be sooty blotch—a fairly harmless but rather ugly condition caused by a variety of fungus (Gloeodes pomigena), plus poor circulation of air around the fruit. High humidity can also be a factor.

What could I have done to help prevent this? Well, when the fruit started to set, I should have started thinning the fruit so that none of the apples were touching, and ideally had about 4-6 inches in between.

Yes, that means picking off developing fruit and tossing it. I know, it feels like a waste. But it accomplishes several things:

  • helps avoid fungal infections like sooty blotch and flyspeck (which often occur together)
  • keeps branches from getting too heavy and possibly breaking
  • diverts more energy to the remaining apples, enabling them to grow bigger

So, once fruit trees drop their blossoms and start to set fruit, get thinning. I wait until my apples are a little smaller than golfball sized. That way I can identify fruit that’s undersized or not as healthy, and get rid of that first, but it’s not so big that the tree has spent a ton of energy developing it.

You might be interested: When to Pick Apples

Apple Tree Care Tip #2: Prune Your Branches

Another factor in fungal disease is branches that overlap each other, crowding the fruit and keeping them from getting enough air and sunshine.

I have no idea how long it had been since the tree had been pruned, but I’m guessing maybe never—the previous owner didn’t take very good care of the house or the yard.

You never want to prune mid-season, EVER. Even if you’ve discovered problems with fungus. It can irreversibly damage the tree. Wait until the tree goes dormant, and then right before it starts budding (January or February) prune it.

Prune away any dead or damaged limbs first. Keep track of limbs that aren’t producing during the growing season. If you need to, mark them with tape so that you can tell them apart from healthy branches when the tree is dormant. Dead branches will often be scaly and black, while healthy branches will be light grey, and will bud and leaf out as usual.

Then prune any “suckers”—any outgrowth where an old branch has been trimmed off.

Next, prune back any limbs that are crossing over others, growing out and then straight backwards, or growing straight downward. It happens…apple trees are weird, gnarly trees that grow in all kinds of funky directions.

Here’s a great how-to article on pruning fruit trees if you want visual examples!

Apple Tree Care Tip #3: Use a Fungicide

Early in year 2 of owning an apple tree, I was raring to go. I had pruned my tree and thinned the fruit. And then…GAH.

All these bright orange spots started showing up on the leaves. Some research led me to an answer: Cedar apple rust.

Cedar trees can harbor a fungus that grows on its galls (kind of like seed pods). When the galls drop, the fungal spores spread—and they can spread for a mile or more, so it might not be from a tree in your yard! I know, super frustrating.

The worst thing about cedar apple rust is that it causes apples to drop before they’re fully ripened. In other words? It destroyed my hope of any sort of apple harvest that year. The solution? Spray your apple tree with a fungicide.

I use a copper fungicide that’s considered organic. It’s great for controlling a whole list of common fruit and vegetable diseases. I also use it on my peach tree to prevent peach leaf curl.

BUT you need to make sure you:

• dilute it properly according to package directions

• do NOT use it while the tree is in bloom because it can hurt pollinators

• use it sparingly…too much copper can contaminate soil

Using an all-purpose compression sprayer, I mix the prescribed amount of water and copper fungicide, then spray evenly on the trunk, branches and buds. You can reapply it throughout the season. I do it about once a month.

Copper fungicide will NOT get rid of an existing fungal infection. It’s meant to be a preventative measure. And it may not even really help control one—but it’s worth a try. If you’ve applied it and things seem to just be getting worse, I’d recommend cutting your losses and starting fresh next year.

I know, it sucks. I’ve done it.

Apple Tree Care Tip #4: Use a Dormant Spray

If you’ve noticed a pest problem on your fruit tree, like maggots, moths or borers, you’ll also want to spray your tree with dormant oil the following year. Just like pruning, you’ll want to spray the tree while it (and the bugs and eggs hanging out in its bark) are dormant for the season, like late winter or early spring.

Try to spray on a sunny day above 40° and make sure you dilute it according to package directions. You have to be really thorough with your spraying. Coat branches, twigs and the trunk as evenly as possible. And don’t forget the undersides!

There are organic dormant oils, including neem oil, which is what I prefer. It’s often found in cosmetics, soaps and other household products. The oil is not a pesticide—it kills by smothering the bugs and eggs or disrupting their hormones. Not pleasant, but it’s them or your fruit!

Apple Tree Care Tip #5: Prop Up Your Branches When Needed

One apple isn’t heavy. But fifty apples? That’s pretty dang heavy!

Apple tree fruiting tends to go in cycles. One year it’ll be suuuuper heavy, the next it’ll be a little lighter, as the tree tries to get some strength back after producing so much the previous year.

On those super heavy years, in addition to thinning your fruit, you might also need to support your larger branches. Propping is especially needed during the last month before harvest, as fruit will just keep getting bigger and heavier.

Anything that seems like it’s under a great deal of stress—i.e., brushing the ground when it’s usually eight feet up in the air during the dormant season!—should be propped up to help keep the branches from breaking under their own weight. Here’s how:

  • Get a 2×4 and cut the bottom corners off to create a “V” like the bottom of a stake
  • Drive the lumber down into the ground at least a foot (more if you can) with a sledge hammer, near the branch that needs support
  • Notch the top of the 2×4 into an empty “V”—this is where the branch will sit, and the notch will help keep the branch from slipping off
  • With the help of another person, gently lift the branch up and set it down into the notch

The 2×4 will probably lean a little bit, but that’s okay. As long as it stays anchored in the ground, it should be fine, but it’s worth checking on these props every day or so. The props can be removed right after harvest, and stored in a shed until next year, when they’re needed again.

Apple Tree Care Tip #6: Planting a new tree? Keep the grass cut back.

When I read about this recently, I was blown away! Research from K-State’s John C. Pair Horticultural Center has shown that controlling grasses around newly planted trees helps them grow stronger and faster.

Trunks, top growth (branches) and leaf area were all shown to be greater for trees that had bare soil or mulched soil at its base. So when you’re planting, cut back your grass in a circle around the base of the tree—a minimum of three feet from the trunk.

While you can leave the top of the soil bare, mulch will help keep the soil from drying out too quickly, conserving moisture and keeping you from having to water your new tree quite as often. It will also suppress weeds!

With these 6 tips, you should be on your way to a productive apple (or any other fruit tree!) harvest. If you’ve had other issues, tell me about them!

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Integrated Pest Management

Fact Sheets > Fruit > Tree fruit > Apples

Insect, Mite and Disease Control for Apples

At least 30 different insects, mites and diseases commonly attack apple trees in Connecticut. Unfortunately, they are not all present at the same time but appear in a definite sequence from the time buds break dormancy until the fruit is ready to be harvested. Therefore, it is not possible to apply two or three sprays and expect to harvest insect and disease-free fruit.

If the insect, mite and disease recommendations (contact your local Cooperative Extension center for up-to-date management options) are followed carefully, you should obtain a high percentage of clean fruit from a home planting. The proper timing of spray applications and thorough coverage of leaves and fruit are as important as the spray materials used. Be sure to cover all surfaces of the tree.

General-purpose mixtures have been found to be safe and effective for the control of fruit pests. This mixture is available under a variety of trade names at most garden supply shops. In addition, individual ingredients of various products are available in small packages and can be mixed at home prior to spraying.



Green Tip: when green tissue first shows from buds.

Red mite eggs and scale insects.

Half-Inch Green: when half-an-inch of green tissue projects from the buds.

Scab and rosy aphids.

Tight Cluster: about seven days after Half-inch Green when blossom buds appear in a tight cluster. Center bud may show some pink color.

Scab, rusts, black rot, powdery mildew, rosy aphid, leafroller and caterpillars

Pink: when blossom buds separate from the cluster and all show a pink color but before blossoms open.

Same as above plus red mites.

Bloom: when 10% or more of the blossom buds are in bloom

Scab, rusts, black rot and powdery mildew

Petal Fall: when 90% or more of the blossoms have fallen. Sprays applied sooner may kill pollinating insects.

Same as above plus curculio, codling moth, leafrollers and codling moth.

First Cover: about one week after Petal Fall.

Same as above plus sawfly.

Second Cover: about one week after First Cover.

Same as above plus apple aphid.

Third Cover: about two weeks after Second Cover, mid-to-late June.

Scab, fruit rots and spots. Apple aphids, curculio, codling moth and mites.

Fourth to Eight Covers: apply when needed until early September.

Scab, fruit rots and spots. Apple maggot, aphids, mites, leafrollers and codling moth.

Contact your local Cooperative Extension Center for up-to-date management options including cultural practices, biological control and chemical control (organic and non-organic).

Revised by: Edmond L. Marrotte, Consumer Horticulturist, Department of Plant Science, University of Connecticut

Updated by: Mary Concklin, UConn IPM. 2012

The information in this document is for educational purposes only. The recommendations contained are based on the best available knowledge at the time of publication. Any reference to commercial products, trade or brand names is for information only, and no endorsement or approval is intended. The Cooperative Extension System does not guarantee or warrant the standard of any product referenced or imply approval of the product to the exclusion of others which also may be available. The University of Connecticut, Cooperative Extension System, College of Agriculture and Natural Resources is an equal opportunity program provider and employer.

Pests & Diseases

Home ” The Big Picture ”

Integrated Pest Management (IPM) is a method of encouraging natural predators to control pests in your garden or orchard. Nature provides a balance between plant pests and the beneficial insects that control these pests. The less we do to tamper with that balance, the more likely it is to work successfully. How does it differ from organic gardening? Proponents of IPM are not opposed to the use of chemical controls, but use them only when necessary and only in amounts and with proper timing to minimize a negative effect on the beneficial bugs in the garden.

  • Learn to recognize the beneficials. Knowing the good bugs is important in assessing the situation in your garden.
  • Use preventive sprays. “Managing Pests and Disease in Your Home Orchard” is a valuable publication to help you know when and what to spray.
  • Use no spray before its time. Using the safest spray at the right time, only if necessary, is the essence of IPM.
  • Plan ahead. Planting the right plant at the right time in the right location will help you minimize problems.

Natural predators such as lacewings, leatherwing beetles, ladybird beetles, ground beetles, wasps, praying mantis and pirate bugs will control or contain most pest populations at an acceptable level, especially if trees are kept vigorous, orchard areas are kept clean of trash and weeds, and trees are well pruned to facilitate good air movement. Home orchardists have little need to completely eradicate pests.

Most insect and mite pests of fruit trees are controlled by many beneficial species of insects and mites found in the orchard. Do not spray pests unless you are certain they are present in damaging numbers or this publication suggests you do so. Unnecessary sprays reduce control provided by beneficial species and may result in added damage from pests freed from their natural controls.

Several of the most common fruit tree diseases may be controlled by using the proper fixed copper spray during the dormant season. These diseases include: bacterial canker, brown rot, coryneum blight and peach leaf curl. See individual fruit tree pages for descriptions. Be certain to follow directions on the package exactly whenever sprays are used.

Beware: some fungicide brands recommend inadequate amounts of copper for peach leaf curl. There are numerous fixed copper materials. We recommend one that contains 50% actual copper. Do not store Bordeaux from one year to the next.

How Pests, Diseases, and Hosts Fit Together

The tables, below, are brief formats designed only as guides to be used with Integrated Pest Management (IPM) and other research-based references. If one or more of these pest and disease problems are not present, do not apply preventatives. Many do not become problems until trees begin to bear.


Fruittree Leafroller on Ornamental and Fruit Trees, UC IPM
Ferrisia gilli: A Mealybug Pest of Pistachios and Other Decidious Crops, David Haviland, Robert Beede, Kris Godfrey, Kent Daane

Goals for reducing insect and mite damage in home orchards are to:

  • Protect trees and crops from substantial damage
  • Make it simple and easy
  • Make it safe
  • Use methods that enhance natural control factors

Dormant season treatments are most important since they will not kill beneficial insects. One spray controls many orchard pests. The following tables of Orchard Pests by Season list several common home orchard pests and include information on damage, description, life cycle, and control options. More importantly, it provides information on the seasons when these pests should be addressed if they are problems in the home orchard. When damage becomes obvious, it is often too late to treat with successful results for that year.

  • Dormant
  • Petal Fall to Harvest
  • Summer
  • Green Tip – Petal Fall

Orchard Pests by Season: Dormant

San Jose Scale


Most deciduous fruit and nut trees.


Gets on fruit, kills shoots.


Gray scale with yellow body.

Life Cycle

Three generations, overwinters as immature black cap stage.


Natural: limit tree size; lady beetles and parasitic wasps (avoid summer sprays).
Spray: See Calendar of Backyard Gardening Operations

Leaf Curling Aphids


Apple, plum, cherry, and others.


Rolled, stunted leaves; stunted and distorted fruit; honeydew drip.


Apple aphid (rosy purple); green apple aphid (small and green); mealy plum aphid (pale, green, waxy); black cherry aphid (shiny, black); leaf curl plum aphid (yellow green, shiny).

Life Cycle

Overwinters as eggs on tree. Eggs hatch as tree leafs.


Natural: Control may not be sufficient. Aphids develop before natural enemies build up.
Spray: See Calendar of Backyard Gardening Operations

Pear Psylla




Honeydew with sooty mold, leaf burn, pear decline, leaf curl.


Adult looks like miniature cicada, one-tenth inch; nymph yellow to brown at 5th nymph stage.

Life Cycle

About five generations a year; overwinter as adults.


Natural: Predators and parasites (avoid summer sprays).
Spray: See Calendar of Backyard Gardening Operations

Blister or Rust Mites


Pears for pear blister, pear rust; peach and nectarine for peach silver.


Pear blister/rust russet fruit surface, blister, and damage leaves. Peach silver damages leaves.


Mite: need hand lens to see, white to tan.

Life Cycle

Overwinters under bud scales and adjacent to leaf buds; many generations.


Natural: Predaceous mites (avoid summer chemical sprays).
Spray: See Calendar of Backyard Gardening Operations

Peach Twig Borer (PTB)


Peach, nectarine, almond, apricot, plum, prune.


Invades fruit and kills new shoots. Fruit feeding usually superficial, not deep.


Mature larva with chocolate brown bands, dark head.

Life Cycle

Several generations overwinter as larva in hibernaculum on tree.


Natural: not reliable.
Spray: See Calendar of Backyard Gardening Operations

Orchard Pests by Season: Petal Fall to Harvest

Coddling Moth (key pest in apples and pears)


Apple, pear.


Worms invade fruit of apple, pear, sometimes walnut, and plum.


Grayish brown moth, about ½ inch, copper tipped wings, larva white with black head, later larva pinkish with brown head.

Life Cycle

Overwinter as larva in cocoons, pupate in spring, emerges as adult early May. Two or three generations possible in Foothills.


Natural: Difficult pest.
Cultural: Sanitation, banding trunks, bagging fruit. Use temperatures to predict egg hatch and pheromone traps to monitor flights and estimate adult population.
Spray: See Calendar of Backyard Gardening Operations

Orchard Pests by Season: Summer



Many fruit and nut trees.


Pale stippling sometimes webbing on leaves; can distort leaves, fruit, blossoms, high numbers cause leaf drop.


Minute true spiders, need hand lens to see: Spider mite, two spotted mite, European red mite, and brown mite.

Life Cycle

Ten days for two-spotted in hot weather.


Natural: Predaceous mites, many natural enemies; avoid chemicals.
Spray: See Calendar of Backyard Gardening Operations



Many hosts.


Honeydew, foliage feeding, shoot distortion.


Wooly apple aphid covered with white cottony wax.

Life Cycle

Many generations. Wooly apple migrates from roots.


Natural: predators (green lacewing, minute pirate bug, syrphid fly, damsel bugs, and many others); parasitic wasps (look for mummies).
Spray: See Calendar of Backyard Gardening Operations

Redhumped Caterpillar


Deciduous trees, especially plum, prune, walnut.


Skeletonizes and strips all foliage on a branch. Young trees especially vulnerable.


Older larvae with yellow body, black stripes, red hump on back and red head.

Life Cycle


Natural: Many natural enemies; pick off, remove clusters by hand.
Spray: See Calendar of Backyard Gardening Operations

Orchard Pests by Season: Green Tip – Petal Fall

Fruit Worms


Fruittree Leafroller and Obliquebanded Leafroller: apple, pear, stone fruit, almond, citrus.
Green Fruitworm: apple, pear, plum, prune, cherry, apricot.


Feeding on young fruit and leaf some foliage loss, rolling and webbing.


Fruittree leafroller: black with black-headed larva drops on spun thread.
Green fruitworm: green larva, large when mature, 1½ inches long.

Life Cycle

One generation, early season only; overwinters as eggs.


Natural: Some predators when larva are small, birds later on.
Spray: See Calendar of Backyard Gardening Operations



Many hosts.


Spot on apples and pear, catfacing on nectarines, plums and peaches, cause depressed cavities on apples, distort fruit on pears.


Flower thrips, madrone thrips, pear thirps. 1/20 inch when adult, long and slender.

Life Cycle

Flower thrips have many generations, heavy numbers after warm winters, low after very wet winters.


Natural: Modify habitat (avoid adjacent weedy or grassland area that dry up), encourage parasites, remove host plants, sanitation.
Spray: See Calendar of Backyard Gardening Operations

Plant Bugs


Apple, pear, stone fruit, and other hosts.


Fruit dimpled and pithy.


Consperse stinkbugs most damaging, gray-brown to green black speckled legs, shield shaped, ½-inch. Conchuela, red shouldered and a number of other stinkbugs; Lygus, false chinch, leaf-footed box elder and others.

Life Cycle

Two generations for consperse, overwinters as adult. Same for other bugs.


Natural: Encourage parasites, remove host plants (ground covers and weedy areas), sanitation.
Spray: See Calendar of Backyard Gardening Operations

Pacific Flatheaded Borer


Many deciduous fruit and nut trees.


Mine and girdle trunks of young trees and limbs of older trees.


Larva with large flat head and white body, ½- to ¾-inch long.

Life Cycle

Overwinter in xylem as pupae; adults emerge in early summer and lay eggs on sunburned or damaged tissue.


Cultural: Whitewash trunks to prevent sunburn; prune to shade larger branches.
Spray: See Calendar of Backyard Gardening Operations


Please read Home Orchard Weed Control by Paul Voosen, Farm Advisor UCCE Marin-Sonoma Co.

Weeds can have a dramatic effect on tree growth by competing for soil moisture, physical space, and nutrients. Some weeds might even have an antagonistic or allopathic effect on trees. Experiments comparing various weed control methods have demonstrated that young trees can be reduced in their growth by 1/3 to 1/2 in the first few years if weeds are allowed to compete with trees compared to treatments with no weeds.

One of the best ways to maintain the area under home orchard trees is completely weed free with an organic mulch. The mulch keeps the soil moist, reduces evaporation, and as it breaks down, it releases nutrients to the tree. It must be at least 3 inches deep to adequately control weeds and will need to be reapplied periodically to maintain that depth. Other mulches such as heavy-duty weed cloth is an alternative to organic mulches, which eliminates the need for frequent reapplication. The best weed cloth barriers will block all the light, control all the weed growth, allow water to pass through, and last 5–10 years. Another advantage is that it can be easily cleaned off of fallen leaves and fruit to prevent the spread of diseases. Mechanical cultivation with a tiller or hand hoe also works; the important thing is to keep the area free of weeds from the beginning of growth in the spring until leaf fall.

In the dormant period, it is not critical to maintain a weed free area under the trees, so cover crops or ornamentals can be grown to improve the soil or just to look nice. Mature trees can tolerate more weeds or turf or cover crops growing within their drip-line since they already have an established root system, are full sized, and don’t need to grow as much.


Control Options for Major North Coast Stone Fruit Diseases in Home Orchards, Rachel Elkins

Conditions that favor fruit tree diseases are wetness and lack of sanitation. The Tables of Home Orchard Diseases, below, list diseases by the area of the tree that is affected by disease and includes conditions favoring the disease, name of the disease, symptoms that might be observed, and prevention tips:

  • Root and Crown Diseases
  • Leaf and Fruit Infections
  • Shoot Infections

Root and Crown Diseases

Crown Rot


Many hosts.


Caused by species of Phytophtora fungus when tree is too wet around crown.


Distress in tree top, reduced growth.


Good drainage, mound soil at planting, don’t over-irrigate.

Oak Root Fungus


Many hosts.


Caused by Armillaria mellea fungus (while fans of mycelium under bark) when tree is too wet around crown.


Distress in tree top, reduced growth.


Use resistant stock, don’t over-irrigate.

Leaf and Fruit Infections

Peach Leaf Curl


Peach, nectarine.


Fungus, wet weather.


Irregular reddish lesions are sometimes seen on fruit.


Apple and Pear Scab


Apple, pear.


Fungus infects when wet from green tip stage through bloom period.


Fungus infects flowers, leaves, or fruit; causes dark scabby areas on fruit, damages leaves.


Blossom Blast / Fruit Brown Rot


Blossom Blast: Stone fruit, pear; Fruit Brown Rot: Stone fruit, almond.


Caused by brown rot fungus or by Pseudomonas syringae bacteria; brown rot produces gray spores.


Pseudomonas attacks only when freezing temperatures occur. Blights or “blasts” buds, blossoms, leaves, green fruit. Cankers. Brown rot fungus blights blossoms, leaves and twigs shrivel; brown or tan spots spread over fruit.


Remove mummied fruit; cut off blighted wood.

Shoot Infections



Pear, apple, quince.


Bacteria, Erwinia amylovora, attacks flowers when wet and mean temperatures are over 60°F.


Bacteria moves into shoots and kills tissue causing blackened leaves and stems.


Cut out infections well ahead of visible injury.

Bacterial Canker


Stone fruit, almond.


Caused by Pseudomonas syringae.


Foliage collapses and dies after leafing in spring due to girdling of branches. A canker develops at the point of infection and dark gum usually is extruded through the bark.


Disease dies out in hot, dry weather. Keep trees vigorous by good cultural practice.

Preventing Apple Pests

Growing your own apple trees is relatively easy, but avoiding insect and disease damage to the fruit requires pruning and prevention.

Tools and Materials

  • Pruning shears and lopper
  • A ladder may be needed if your tree is full size
  • Baited sticky traps
  • Wire mesh trunk guards
  • Mulch
  • Hose-end sprayer
  • Sprays of horticultural oil, liquid sulfur, Bacillus thuringiensis kurstaki, and perhaps phosmet(Imidan)
  • Prune. Prune your apple tree every winter before you detect any signs of new growth. Eliminate crossing branches, watersprouts, and crowded growth. The following pointers will help keep pests at bay.

    Eliminate hiding places. Pick up and destroy fallen fruit, which may contain grubs. Remove plastic and paper tree guards, where adult flies and moths may spend the winter. Replace them with wire mesh guards. Surround trees with mulch instead of grass.

    Smother with oil. In spring just before new leaves emerge, spray trees with nontoxic horticultural oil. The oil smothers dormant insects and their eggs.

    Know your pests. Three common insect pests that damage apple fruits are apple maggot flies, plum curculio, and codling moth. The best time to control these pests is while they are mating and looking for potential egg-laying sites. This is just before early to midsummer, when these insects lay their eggs on or near developing fruit.

    Apple maggot flies appear in June or July to lay their eggs on developing apples. When the eggs hatch, the larvae burrow into the fruit. Trap flies with sticky red spheres and bright yellow 8- by 10-inch rectangles hung in the trees at eye level. Place spheres near fruit clusters about three weeks after flower petals fall; use two traps for a small tree (8 feet tall or less), six traps for a large tree (10 to 25 feet).

    Curculio is a 1/4-inch-long beetle that makes distinctive crescent-shaped scars on developing fruit. The grubs tunnel through the apples, causing the fruit to drop in early summer. To kill the adults, spray phosmet (Imidan) immediately after the blossom petals fall and again a week to 10 days later. (Wear protective clothing and avoid spraying during bee activity.) Nonchemical controls include spreading a tarp under the trees in the morning and shaking the tree to dislodge the pests. Also, raking up and destroying dropped fruit will reduce the local population of these pests over time.

    Codling moths lay eggs on developing fruits shortly after petals fall in spring. Eggs hatch in a few days, and young larvae tunnel into fruits where they feed and mature, destroying the fruit in the process. The best remedy is spraying Bacillus thuringiensis kurstaki in the evening 15 days after petals begin to fall. Repeat five days later. The spray is toxic to caterpillars only.

    If you’ve inherited a disease-prone variety, sulfur sprays can control the disease. Use liquid sulfur, spraying it over the tree once flower buds show pink. Repeat 10 days later.


    To reduce the need for fungicides, choose only disease-resistant apple varieties when buying young fruit trees.

    Avoid all-purpose fruit sprays because they kill many beneficial insects as well as the harmful ones.

    Applying Pesticide on Fruit Tree Pests

    Read carefully the entire label of each material that is to be used.

    Under present federal regulations, it is illegal to apply any pesticide in a manner, rate, or dilution that is not recommended on the label. Check with the county agent or the agricultural research center in your area if there are any discrepancies between recommendations in this handbook and a pesticide label with regard to rates, dilutions, or manner of application.

    Pests and strategies for their management vary throughout the Pacific Northwest. Complete spray schedules are available for the different growing regions of Washington, Oregon, and Idaho. The following insecticides and miticides are the general materials that are available for pest control—not all materials registered for a given use are listed. Specific materials and formulations may be more effective in certain areas of the Pacific Northwest than in others. Be sure to check with your county agent or agricultural research center in regard to specific management programs. Not all label restrictions can be listed here. You must read the label to ensure legal use.

    COMMERCIAL GROWERS: The following materials and formulations presently are registered for use in the Pacific Northwest states for pest control in the various orchard crops. Application rates in the tables are based on current spray practices of up to 100 gallons of water per acre per application, except where the label specifies otherwise or for dormant/ delayed-dormant sprays where the historical dilute spray volumes of up to 400 gal water/acre are still recommended. The label rates are given per acre and must never be exceeded. Tree size, amount of foliage, type of equipment used, and other factors are important in determining the amount of spray solution to use per acre. When applying concentrate sprays (spray volumes of ≤100 gal water/a), use the per-acre rates or a modification of these rates according to the label. IRAC mode of action group numbers are given for each of the chemicals suggested in the following list. To reduce the development of pesticide resistance, users should choose insecticides from these groups in rotation, using where possible at least three different registered groups in succession. (see http://www.irac-online.org/teams/mode-of-action/ )

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