Black Aphid Damage and Control

Discussion in 'Maples' started by SStratman, Oct 3, 2003.

  1. SStratman

    SStratman Member

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    I have approximately 25 cultivars in my yard and nearly 20 of them have developed black spots under the leaves after a recent unseasonably warm day. Closer inspection revealed tiny black insects diagnosed as "black aphids" by a local nursery. Leaves on all affected trees have turned brown or lost color entirely, curled up, and fallen off (No color this fall :( unfortunately). I'm interested in any suggestions on control and damage potential from the infestation. Can the insects damage the trees and how can I avoid a similar experience. Appreciate any input!
     
  2. Douglas Justice

    Douglas Justice Active Member UBC Botanical Garden Forums Administrator Forums Moderator VCBF Cherry Scout Maple Society 10 Years

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    I would recommend that you monitor your plants very closely in the future, both for aphids and for other insects. In general, aphids are not a significant problem on Japanese maples, but aphids have the ability to increase their numbers very quickly, so can become a nuisance. Natural predators, parasites and diseases of aphids are very common, but there is usually a time lag before the natural controls make an appearance.

    While the following advice may seem counter-intuitive, it often provides the best long-term control: Leave some of the aphids alone. If the infestation becomes excessive (foliage is marked or distorted), hose them off the plants. Natural controls will only become established if there is something to prey upon (why show up at the salad bar if there isn't any salad?). Natural aphid-enemies often frequent areas where there are nectar-producing flowering plants.

    This link to a commercial site has an excellent article on attracting beneficials.
     
  3. SStratman

    SStratman Member

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    Thrip not aphids?

    Thanks for the thoughts and link on aphids. My wife was actually quite intrested because of her roses. I've been watching the plants now for 4 weeks without any significant improvement in "infestation". Leaves continued to brown and fall off. I took several leaves to a different nursery and was told it was "thrip". Black bugs leaving black spots and ultimately a brown leaf. New to me, any thoughts?
     
  4. Douglas Justice

    Douglas Justice Active Member UBC Botanical Garden Forums Administrator Forums Moderator VCBF Cherry Scout Maple Society 10 Years

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    Thrips is a possibility -- I'm not as familiar with Japanese maple pests in the Bay area. In general, thrips damage looks like speckling with some ugly black spotting. See this link to the University of Florida.

    Note that western flower thrips is a common pest on roses. In this case, the damage is to the petals (distortion and spotting). See this link to North Carolina State University.

    Damage to ornamentals is usually not extreme, so control measures are seldom recommended. If damage to your plants is severe, it will probably lessen in subsequent years, particularly if you reduce or eliminate the application of pesticides and increase the diversity of your plantings. This will usually allow beneficial organisms to prosper and effectively reduce the impact of thrips or whatever else is affecting your plants.
     
  5. languisdj

    languisdj New Member

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    A population of these insects are covering the branches of a cutleaf Japanese Maple at my home. I have a photo of the bug and I'm intending to treat the plant with Horticultural Oil tonight. Is this a valid treatment?
     
  6. PoorOwner

    PoorOwner Active Member 10 Years

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    I have been using finger to squish them it control the population almost daily
    However it takes alot of time to inspect and I'm always late for work now.

    I believe the aphids is black with wings and after they land on a plant they will turn the color of the sap and lose their wings.. ??
    I am going to use a systemic on my next watering.

    I have a insect spray but it says not to use on JMs.
    Look on the top most new growth and also under the leaves from below you find them and kill them quickly.
     
  7. mendocinomaples

    mendocinomaples Active Member Maple Society 10 Years

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    Do not spray hort oil on a plant in foliage. These oils (though effective) are to be used only when the tree is dormant. You will most likely loose all your foliage if you spray now. Systemic toxins are nasty toxins. Handle with care. They can enter your system if they touch your skin or if you breath the fumes.

    I agree with Douglas, the best method with aphids is to let nature take it's course and biological control will come naturally. I have never lost a tree to aphids, but have lost many trees to a quick fix with this or that special remedy. Hosing them down cuts back on the population. It is a seaonal infestation that will soon pass.

    We have thrips here in Mendocino and they have practically wiped out my native salal. They have never (fingers crossed) affected my maples. I do have a slight problem with black spot which is caused by a fungus. This is due to the prolonged wet spring here in N. CA. The leaves on some of my trees have the same symptoms that you described as aphid damage...curling of leaves and brown and falling off....with black dots (the fungus).

    robert
     
  8. yweride

    yweride Active Member 10 Years

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    I too have black aphids on my A.c. 'Monroe'. Just this morning i noticed small ants crawling throught out the tree. Is it possable that these ants are eating the aphids?
     
  9. SilverVista

    SilverVista Active Member

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    Ants don't eat aphids, they actually "farm" them for the sticky honeydew that they excrete from sucking the sap of tender plants. In other words, the ants use the aphids as food-producing slaves, and are intent on keeping them alive and healthy for that reason. Ah, Mother Nature...ain't she grand?

    The good news is that at this time of year, the axillary buds left when leaves fall off will push new growth again before the summer is out, and there is still hope for good fall color this year.
     

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