Green Apple Aphid — Ontario CropIPM

Apples

Green apple aphid

Beginner

Scientific Name
Aphis pomi

Identification
Eggs:

  • 1 mm long,
  • Shiny,
  • Black,
  • Oval shaped,
  • Rarely seen in orchards.
  • 2 mm in length,
  • Yellow-green to light green,
  • Oval shaped with black cornicles (tail pipes),
  • Five instars.
  • 2 mm in length,
  • Oval shaped,
  • Bright green with black cornicles and legs,
  • Winged or wingless.
  • Reduced vigour and growth of shoots,
  • Reduced bud size and internodes’ length,
  • Leaf curling,
  • Honeydew produced by the aphids may drip onto fruit allowing sooty fungi to grow.

Often Confused With

  • Rosy apple aphid- Immature green apple aphids have shorter antennae and less developed cornicles than immature rosy apple aphids, and are usually found in colonies on young terminals of apple trees. Rosy apple aphids are usually found on foliage, flower stalks and young fruit. Green apple aphids are also green in colour (not pink/purple).
  • Mullein bug- Mullein bug nymphs lack the cornicles that green apple aphids have.

Period of Activity
Eggs hatch when buds burst and the first leaves are unfolding. There are many generations per year. They are most numerous during July and early August and usually remain on apples throughout the summer.

Scouting Notes
Monitor from bud break through harvest. Generally green apple aphids are of little concern after terminals harden off (late July or August). Check 100 terminals in a 4-6 ha block weekly throughout the summer. Pick 10 terminals per tree on 10 trees randomly, without visual bias towards infested terminals.

Be sure to scout for the presence of predators when assessing aphid populations in orchards. Resample orchards with high numbers of natural enemies present within a week to see if predators are providing control (see threshold).

Thresholds
The action threshold for green apple aphid is 400-600 aphids per terminal on 10% or more of terminals checked. If more than 20% of the aphid colonies have natural enemies, delay or eliminate an insecticide application. If sprays are delayed be sure to resample within a few days to monitor populations.

Advanced

The green apple aphid is widely distributed in Canada and the United States and first appears in apple orchards at bud break.

Scientific Name
Aphis pomi

Identification
Eggs are 1 mm long, shiny, black and oval shaped. Nymphs are 2 mm in length, yellow-green to light green, oval shaped with black cornicles (tail pipes) and have five instars. Adults are 2 mm in length, oval shaped and bright green with black cornicles (tail pipes) and legs. Adults can have wings or be wingless.

Green apple aphids are usually found close to major veins on the underside of the leaf. They suck sap from the leaf. Heavy infestations reduce vigour and growth of shoots. Feeding reduces bud size and internodes’ length, and causes leaf curling. Aphid damage can stimulate lateral branch growth and affect tree shape. Honeydew produced by the aphids may drip onto fruit allowing sooty fungi to grow. In heavy infestations, green apple aphids feed on immature apples and cause russetting.

Often Confused With

  • Rosy apple aphid- Immature green apple aphids have shorter antennae and less developed cornicles than immature rosy apple aphids, and are usually found in colonies on young terminals of apple trees. Rosy apple aphids are usually found on foliage, flower stalks and young fruit. Green apple aphids are also green in colour (not pink/purple).
  • Mullein bug- Mullein bug nymphs lack the cornicles that green apple aphids have.

Biology
Green apple aphids overwinter as eggs on suckers at the base of buds on terminal shoots. Eggs hatch when buds burst and the first leaves are unfolding. Newly hatched nymphs are all females. Nymphs begin to feed immediately on developing leaves, and are initially present on terminal shoots, moving later to older cluster leaves. After feeding for about two weeks and molting several times, nymphs mature into wingless adults that reproduce without mating. These adults give birth to live young, with populations building rapidly. Each female can produce 50-100 live offspring. Young aphids develop in 7-10 days. Green apple aphid populations build slowly on apples in early spring (bloom, petal fall), and more rapidly as average daily temperatures increase. Adult aphids in a colony are generally wingless until crowded conditions induce the formation of winged individuals that disperse to new hosts.

In late summer, males are produced as well as females. Females then mate with males and lay overwintering eggs. The greatest numbers of eggs are 15-20 cm from the tips of terminals. Eggs are seldom found on the large scaffold limbs or the trunks of apple trees.

Period of Activity
Green apple aphids overwinter as eggs on suckers at the base of buds on terminal shoots. Eggs hatch when buds burst and the first leaves are unfolding. Green apple aphid populations build slowly on apples in early spring (bloom, petal fall), and more rapidly as average daily temperatures increase. Green apple aphids are most numerous during July and early August. Depending on weather conditions, one generation is completed in two to three weeks. There are many generations per year. Green apple aphids usually remain on apples throughout the summer.

Scouting Notes
Begin monitoring at budbreak and continue until terminals harden off (late July or August). Check 100 terminals in a 4-6 ha block weekly throughout the summer. Pick 10 terminals per tree on 10 trees randomly, without visual bias towards infested terminals.

Be sure to scout for the presence of predators when assessing aphid populations in orchards. Resample orchards with high numbers of natural enemies present within a week to see if predators are providing control (see threshold below).

See also:  Whiteflies: description, elimination of whiteflies

Thresholds
The action threshold for green apple aphid is 400-600 aphids per terminal on 10% or more of terminals checked. If more than 20% of the aphid colonies have natural enemies, delay or eliminate an insecticide application. If sprays are delayed be sure to resample within a few days to monitor populations.

Management Notes

  • If the aphids do not have access to succulent new growth – and they feed on older leaves – the number of young produced drop by up to 50%. As a result green apple aphids are generally not a problem after terminals harden off (late July or August).
  • If temperatures are 30-32В°C and greater, females do not reproduce well. Aphids die when temperatures remain high for several days, and heavy rains wash aphid populations off leaves.
  • A cool, wet spring favours aphid development and is unfavourable for the aphid’s natural enemies.
  • Green apple aphids are one of the few apple pests often managed by biological control. A number of beneficial insects are effective for biological control in apple orchards.
  • The most commonly observed predator of green apple aphid is Aphidoletesspp. (Cecidomyiidae), an orange maggot midge. Other natural enemies (predators) of apple aphids include hover fly larvae (Syrphidae), lacewing larvae (Chrysoperlidae and Hemerobiidae), lady beetle larvae/adults (Coccinellidae), mullein bug (Miridae), minute pirate bug (Anthocoridae), earwigs and some parasitic wasps (Braconidae). The natural enemy complex can be disrupted by insecticides applied against other pests. For more information on the toxicity of pesticides to beneficial insects click here.
  • Manage nitrogen levels in plants to prevent excessive, lush terminal growth and help reduce aphid populations.
  • Avoid summer pruning until terminal buds have set to prevent re-growth of shoots that are very attractive to aphids. Hand suckering in early June removes unnecessary vegetative growth that attracts green apple aphid.
  • See OMAFRA Publication 360, Fruit Crop Protection Guide Chapter 2 Apples or Apple Calendar only :
    • Recommendations for green apple aphid at Special sprays, as well as in Non-bearing orchards

www.omafra.gov.on.ca

Apple-Aphid

Apple grain aphid (Rhopalosiphum fitchii)
Green apple aphid (Aphis pomi)
Rosy apple aphid (Dysaphis plantaginea)

Pest description and crop damage Apple grain aphid is light green with a distinctive green stripe down the middle of the back. Apple grain aphids infest apple buds in the early part of the season, often becoming apparent at green tip. Apple grain aphid is typically not economic and its early appearance may jumpstart aphid natural enemy populations. Green apple aphid is dark green and is present throughout the growing season on foliage. It may be more problematic on green and yellow apple cultivars. Heavy populations can feed directly on the fruit, which may be marked, or honeydew can cause sooty mold marking.

Rosy apple aphids are rose-purple. Their feeding causes severe leaf curling, along with honeydew and sooty mold. Fruits of certain varieties can be stunted and deformed by early-season feeding. The best time for control is before bloom. Once leaves are severely curled, aphids are extremely difficult to kill.

Scouting and thresholds Begin observing growing shoots in late May as shoot leaves are expanding rapidly. About four to five infested leaves per shoot indicates a problem. Aphid identification is necessary to guide treatment decisions as apple grain aphid and green apple aphid are typically less damaging.

Aphids have many natural enemies including lady beetles, syrphid fly larvae, green lacewings, and parasitoid wasps. Avoid broad-spectrum insecticide applications that disrupt these controls.

Aphid populations tend to be higher in plants that are fertilized liberally with nitrogen because aphids prefer succulent new growth.

Home orchardists: Wash aphids from plants with a strong stream of water or by hand-wiping.

Management-chemical control: HOME USE

Stages 0-1: Egg control with dormant & delayed-dormant sprays

Apply sprays during dormant or delayed-dormant period (March to April). Do not use after pink appears in buds. Use enough water to cover the entire tree thoroughly including small limbs and shoots.

  • horticultural mineral oil-Some formulations OMRI-listed for organic use.

Spring and summer

If leaves become severely curled by rosy apple aphids, control is very difficult. Do not apply after blossoms open.

  • acetamiprid
  • azadirachtin (neem oil)-Some formulations are OMRI-listed for organic use.
  • Beauveria bassiana -Some formulations are OMRI-listed.
  • carbaryl-Highly toxic to bees.
  • esfenvalerate-Highly toxic to bees.
  • gamma-cyhalothrin-Highly toxic to bees.
  • horticultural mineral oil-Some formulations are OMRI-listed for organic use.
  • imidacloprid-Soil drenches may have residual activity in woody plants lasting for 12 or more months. If short-term management is the goal, consider other approaches. Highly toxic to bees.
  • insecticidal soap-Some formulations OMRI-listed for organic use.
  • kaolin-Applied as a spray to leaves, stems, and fruit, it acts as a repellant to target pests. Some formulations are OMRI-listed.
  • lambda-cyhalothrin-Highly toxic to bees.
  • malathion-Highly toxic to bees.
  • permethrin-Highly toxic to bees.
  • plant-derived essential oils-Some have shown efficacy against aphids. Some formulations are OMRI-listed for organic use.
  • pyrethrins (often as a mix with other ingredients) -Highly toxic to bees. Some formulations are OMRI-listed for organic use.
  • spinosad-Highly toxic to bees. Some formulations are OMRI-listed for organic use.
  • zeta-cypermethrin-Highly toxic to bees.

Management-chemical control: COMMERCIAL USE

Stages 0-1: Egg control with dormant & delayed-dormant sprays

  • chlorpyrifos (Lorsban 4E) at 1.5 to 4 pints/a + horticultural mineral oil at 6 to 8 gal/a in up to 400 gal water. Cold or dry conditions may cause Lorsban 4E oil sprays to infuse into trees, resulting in bud damage or bud drop. Do not apply until winter rains or irrigation has replenished soil moisture such that bark and twigs are not desiccated. Only one application of chlorpyrifos can be made per year. Organophosphate insecticides are highly toxic to birds and fish. Avoid drift to open water and maintain buffers. REI 4 days. [Group 1B]
  • diazinon (Diazinon 50W) at 4 lb/a + horticultural mineral oil at 6 to 8 gal/a in up to 400 gal water. Dormant or delayed dormant use of diazinon is limited to one application. Delayed-dormant control with oil, plus an organophosphate, is most effective for scale control. Organophosphate insecticides are highly toxic to birds and fish. Avoid drift to open water and maintain buffers. REI 4 days. [Group 1B]
  • Narrow-range horticultural mineral oil at 6 to 8 gal/a in up to 400 gal water. REI varies by formulation; see label. Some formulations are OMRI-listed for organic use.
  • lime sulfur (Calcium polysulfide)-Formulations vary; see label for rates. May be mixed with horticultural mineral oil at 6 to 8 gal/a in up to 400 gal water. REI 2 days. Some formulations are OMRI-listed for organic use.
  • pyriproxyfen (Esteem 35 WP) at 4 to 5 oz/a in up to 400 gal water. Apply by ground with airblast equipment in a minimum of 50 gal/a. Thorough coverage is critical for control. It is essential to use adequate water volume to ensure thorough coverage. Apply at delayed-dormant through pink. REI 12 hr. [Group 7]
See also:  How to Make Insecticide with Boric Acid - 6 steps

Stages 3-4: Prepink & tight cluster sprays

  • acetamiprid (Assail 70WP) at 1.1 to 1.7 oz/a in up to 100 gal water per application. Do not make more than 4 applications per year or exceed 13.5 oz/a per growing season. REI 12 hr. [Group 4A]
  • diazinon (Diazinon 50W) at 4 lb/a in up to 100 gal water per application. Dormant or delayed dormant use of diazinon is limited to one application. REI 4 days. [Group 1B]
  • flonicamid (Beleaf 50 SG) at 2 to 2.8 oz/a in up to 100 gal water per application. Use a minimum of 50 gal water when applied by ground. Do not apply more than 3 applications per season. REI 12 hr. [Group 9C]

Spring and summer

  • acetamiprid (Assail 70WP) at 1.1 to 1.7 oz/a in up to 100 gal water per application. Do not make more than 4 applications per year or exceed 13.5 oz/a per growing season. REI 12 hr. PHI 7 days. [Group 4A]
  • Chromobacterium subtsugae (Grandevo) at 2 to 3 lb/a. Under heavy pest populations, apply a knockdown insecticide prior to or in a tank mix, use the higher label rates, shorten the spray interval, and/or increase the spray volume to improve coverage. REI/PHI 12 hr. OMRI-listed for organic use.
  • clothianidin (Belay 50WDG) at 2.1 to 3.2 oz/a in up to 100 gal water per application. Do not apply more than 6.4 oz/a per growing season. REI 12 hr. PHI 7 days. [Group 4A]
  • diazinon (Diazinon 50W) at 4 lb/a in up to 100 gal water per application. Do not apply more than one in-season application per season. REI 4 days. PHI 21 days. [Group 1B]
  • flonicamid (Beleaf 50 SG) at 2.0 to 2.8 oz/a. Use a minimum of 50 gal water when applied by ground. Do not exceed three sprays per season. REI 12 hr. PHI 21 days. [Group 9]
  • imidacloprid (Provado 1.6F) at 8 fl oz/a in up to 100 gal water per application. Do not use within 10 days prior to bloom or when bees are actively foraging. Do not exceed 40 fl oz/a per season. REI 12 hr. PHI 7 days. [Group 4A]
  • pyridaben (Nexter) at 6.6 to 10.67 oz/a in up to 100 gal water per application. Only one application per season. REI 12 hr. PHI 25 days. [Group 21A]
  • pyriproxyfen (Esteem 35 WP) at 3 to 5 oz/a per 100 gal water. Do not exceed two applications of Esteem 35 WP per acre per season. REI 12 hr. PHI 45 days. [Group 7C]
  • spirotetramat (Movento) at 6 to 9 fl oz/a in up to 100 gal water per application. Do not exceed 25 fl oz/a per growing season. Do not apply until after petal fall. REI 24 hr. PHI 7 days. [Group 23]
  • thiamethoxam (Actara WDG) at 4.5 to 5.5 oz/a in up to 100 gal water per application. Do not exceed 16.5 oz/a per season. Actara is extremely toxic to bees. REI 12 hr. PHI 35 days. [Group 4A]
  • thiamethoxam/chlorantraniliprole (Voliam Flexi) at 6 to 7 oz/a in up to 100 gal water per application. Do not apply exceed 16 oz/a per season and do not use an adjuvant within 60 days of harvest. REI 12 hr. PHI 35 days. [Group 4A]

pnwhandbooks.org

Aphids – Pest of the Month

Aphids at a glance

Type of Damage Pierce-sucking
Plant Symptoms Stunted growth, leaf curl, transmit diseases
Favourite Plant All plants
Occurrence Year-round in areas with mild winters (SA)
Distribution Worldwide
Control Difficult, physical preferable, biological control agents available

Aphids are an ubiquitous pest species, if you have ever taken care of a plant – you would have most certainly run into these nasties! I absolutely loathe aphids – my friend could never understand why until she started a vegetable garden herself, now she is as much an aphid hater as me LOL! They multiply at an enormous rate and no plant is beyond their reach, they are equally difficult to control and counteract, especially when tended to by ant herders.

Aphids belong to eponymous family, Aphididae, contained within the larger order of Hemiptera. They were previously grouped under the order Homoptera, which included soft-bodied insects whose wings are fully membranous, but recently they have been placed with Hemiptera along with insects whose wings are partially hardened elytra. They are placed under the Sub-order; Strenorrhyncha and Superfamily; Aphidoidae.

Aphids have a worldwide distribution and can spread passively by wind or through human transportation. About 4400 species are presently described and 250 species are known agricultural pests, allowing the family as a whole to feed on a wide range of plant hosts.

Many people believe ( me too at some point ) that aphids are generalists and feed on whatever plants are available, but strikingly a lot of aphids are monophagous, meaning they are plant species-specific. Hence aphids are named after the host plant they infest, such as the green apple aphid ( Aphis pomi ) or the common rose aphid ( Macrosiphon rosae ). To the vegetable gardener aphids can be a huge problem amongst plants of the cabbage family (including Asian greens, cauliflower and broccoli), tamarillos and plants that have been newly transplanted or are still establishing.

See also:  How to prevent winter moth caterpillars from damaging trees and shrubs

During the majority of the aphids’ life cycle they reproduce asexually by means of parthenogenesis and thus offspring are essentially cloned females. Aphids are one of the few insects to bare live young (viviparous) even without prior fertilisation. Aphids produce eggs after sexual reproduction when the host plant becomes crowded or temperatures drop and daylight decreases towards winter. Wingless (clone) females produce sexual male and female clones, these mate and the subsequent eggs overwinter until favourable conditions arise in spring. Winged aphids are also produced during unfavourable conditions and are whisked away by the wind to colonise new plant hosts at a distant site. Aphid populations explode easily due to the high reproductive rate of clone females, which are capable of producing up to 41 generations (each have a lifespan of 20-40 days) leading to thousands of aphids in as little as a month.

Aphids first colonise the underside of plant leaves and then move towards the upper side. Their presence is made known by the curling of leaves and stunted growth of the host, especially new shoots which are easier to pierce with their siphon mouthparts. Feeding aphids reduce the vitality of plant hosts by the removal of plant sap, injecting salivary secretions that suppress host defences and transmission of plant viruses. Aphids produce a sugary waste product (honeydew) that can accumulate on leaf surfaces giving them a shiny appearance and in humid weather this build-up can encourage the growth of black sooty mildew, which weakens the host plant even more.

Be aware that if you do use synthetic chemical control. Most of these products are general insecticides and are harmful to other insects, which do not include pest species. Aphids become resistant to chemical pesticides quite quickly due to their extreme reproductive capacity that allows resistant offspring to multiply quickly. For more information see my post on Pesticide Resistance. Chemical control on the eco-friendly side includes neem or lantana-based products, which can be a bit pricey or hard to find.

Homemade soap solutions and horticultural white oil can also be applied to infestations as spray-on applications, but I suspect you would have more success by rubbing the plant down with a soft cloth soaked in the solution and rinsing out the accumulated aphids. Physical control is usually the most effective, but can be time consuming or laborious. Physical control measures includes spraying them with a jet of water, but considering the drought we are experiencing – this might not be preferable. If you don’t mind getting your hands dirty, small infestations can be wiped out by squishing them by hand! You can find my Environmentally Friendly Aphid Control Recipes on my Pest Control Page.

Else you can wait for the natural insect predators of aphids to arrive, but they will likely only do so when you have an infestation of catastrophic proportions! Biological control includes aphids predators, such as jumping spiders, baby mantids, adult lacewings, adult and larval lady bugs as well as the larvae of hoverflies. Please be careful not to destroy already present predators, such as larvae, which are small and sometimes camouflage themselves as pest species. I had a huge infestation of aphids on my fennel one year and decided I was too lazy to spray them the whole time (as eco-friendly controls take multiple applications to work). After some time an army of lady bugs arrived and sorted the aphids in double-quick time – it was quite impressive (and I’ve never had so many ladybugs in my garden before!). You can check out my posts on Biological Control for Ladybeetles, Praying Mantids and Spiders. Other bio-controllers would be parasitic wasps, which you can purchase, but they are more suited to greenhouse release as they fly away easily in open gardens. My Wasp Biological Control post also includes other members that will do away with larger pests such as caterpillars. Having shelter and alternative food plants (for non-predatory lifestages) helps to attract biocontrol agents to your garden, you can have a look at my Insectary Post on how to construct a haven for these insects.

Something Interesting: Aphid Art

Aphids have a mutualistic relationship with ants, this means that both species benefit from the presence of the other, but can also survive and thrive without one another. Ants are herders of many pest species, such as aphids and scale. As aphids feed they produce a sugary waste product known as honeydew, which ants collect as a food source. The ants in turn protect the aphids from predators and some ants even transport aphids between plants for re-establishment when the ants move to new nesting sites. Ants therefore compound the aphid control problem by actively participating in the infestation. Be on the lookout of large masses of ants running the length of your plants as this is indicative of an aphid farm underway. The homemade soap/oil solutions I have suggested should dissuade the ants as well, but since ants are persistent they’ll likely re-appear with a new aphid farm in a few weeks. On another note; here is an artist’s illustration on the subject, which I thought was thoroughly amusing.

whiskerflowers.wordpress.com

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