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kitova

best treatment for magnolia scale NOW

kitova
17 years ago

hi guys, i think i have magnolia scale on one of my new magnolias. they are small sesame seed sized insects covering my magnolia branches and thick stems and they are black in color.

what is the best way to get rid of them now? i tried neem oil and it didn't seem to do anything to them. i've heard of horticultural oil. is that any different than neem oil? is there a better remedy to control them right now?

thanks in advance,

linda.

Comments (42)

  • ginkgonut
    17 years ago

    Neem will work, but it has to be sprayed at the right time. The crawler life stage of the scale, which is very vulnerable to insecticides, is active in late August and September. Horticultural oil can be used in early spring (probably late March-early April in your area) or late fall.

    Depending on how bad the infestation is, you could also consider pruning out the most heavily infested branches now.

    You could also try a soil drench of Imidicolprid. This is the insecticide in Bayer Advanced tree and shrub care. It is systemic and kills them when they feed. It does take time to act so you may want to combine this with a spray in late August or Sept.

    Here is a link that might be useful: Magnolia Scale

  • ginkgonut
    17 years ago

    Came across this article on using the bayer product in the spring for magnolia scale. You'll have to scroll down a bit to "Bug Bytes"

    Here is a link that might be useful: Imidacolprid for Magnolia Scale

  • kitova
    Original Author
    17 years ago

    hi ginkgonut, thanks for the info. but since then something horrible has happened to my plant. i guess i sprayed horticultural oil yesterday before i read your post, and today the whole plant looks like it's been burned by the spray. all the leaves look brown and damaged, i'm quite a bit upset by this. does horticultural oil do this? or was it because a few days ago i put neem oil on and the mix of the two oils burned the plant. i saw no warnings on either label except for for in the case of previous sulfur applications.

    at this rate, what are the chances my magnolia will leaf out again with new leaves? and now i'm a little disinclined to put imadicloprid down because the plant is probably really stressed.

    pruning out affect limbs is not an option because it's a stellata, a very small magnolia and all the limbs are affected. honestly, the plant was much healthier before i treated it with anything, even with the scale insects on there. the insects were small.. little black specks so maybe if i had been a little more cautious with my treatment, i would be in this predicament, but here i am.. in a mighty big pickle..

    any suggestions...?

    - a very disturbed and chastened magnolia mother.

  • kitova
    Original Author
    17 years ago

    oh and NOW i learn about phytotoxicity. *sigh* i made sure to follow the appropriate label instructions too and they did not mention not to spray on a sunny day. i'm pissed.

    http://www.hort.uconn.edu/ipm/homegrnd/htms/33hoils.htm

    http://forums.gardenweb.com/forums/load/citrus/msg1214034830908.html

  • rhizo_1 (North AL) zone 7
    17 years ago

    The application of horticultural oil can be complicated sometimes. Timing is critical. For example, a summer mixture can be applied in the heat of the summer, but can do damage in the newest spring foliage.

    My suggestion to anyone who has experienced plant damage in association with a chemical product is to call the 800 number you will find on the label. Be sure to tell them the whole scenerio, including the neem. The neem use may have be the culprit, or the timing, or weather, etc. You haven't used any detergents, have you?

  • kitova
    Original Author
    17 years ago

    hi rhizo.. no i haven't. i'm going to call the 800 number now... but must calm down first... :/

  • ginkgonut
    17 years ago

    Just curious how new the magnolia is? It kind of sounds like a serious infestation for a new plant.

  • kitova
    Original Author
    17 years ago

    hi, ok so i set my hose on shower and gave the magnolia a good washing. looks like i'll lose at least 30% of the leaves but will have to just wait and see.

    ginkgonut, we put the magnolia in last fall, i'd say in september. it's obvious now that it was infested when we bought it at the nursery, although it must not have been a very big infestation since we would have noticed if there were masses of bumps on the stems and trunk. we found only a few (5 or 6) old adult shells this spring still clinging onto the plant. the masses of tiny black things sucking on the trunk now must be the overwintered nymphs.. i am guessing they are still young. to prevent a major infestation by summer/fall, i wanted to do some preventive treatment.

    as it is, before i hosed down the plant with water, i went in manually with some paper towels soaked in plain water and wiped down the whole plant to remove all the black scale that i could. i'd say i got at least 90% of the critters off the bark.

    when i called the 800 number they offered the same remedy i already did, which is to hose down/wipe down the plant. they figured that the application of neem and horticultural oil combined with a sunny day could have suffocated the leaves leading to the burn occurred... they recommended i do not apply any systemic until 2-3 weeks to let the plant recover.

    i guess i'll just wait and see now. at least i am more calm than this morning! i have other magnolias in my yard which are not affected, so my conclusion is that the infestation came from the nursery. bummer, ain't it?

  • chefann
    16 years ago

    I feel your pain! We have been battling scale for YEARS on our magnolia tree. Does it ever completely go away? If not, I am really ready to throw in the towel on the whole thing and just take it out. Am also not comfortable with the insecticides being used so close to our patio and bird-feeding areas. Does anyone know if there is a permanent solution, or is this something chronic?

  • kitova
    Original Author
    16 years ago

    hi chefann, so far so good this year, no sign of scale reinfestation. i can only guess based on my limited experience that a manual wipe down with damp cloth while the scale insects are still small black sesame seed sized critters would be the best and safest method of removal. it certainly wouldn't harm your tree. although in practice, you might have a harder time wiping down a tree than i had with my 5' tall star magnolia.

    Have you tried spraying in the fall (when scale crawlers are susceptible to contact sprays) with an organic contact insecticide like neem oil? Neem oil is actually a biological product - oil taken from the neem tree (http://en.wikipedia.org/wiki/Neem_oil) that works as an organic insecticide and insect repellant but is safe for mammals and birds.. just be careful with it, don't spray when it's really hot, and also i think it's toxic to bees..

  • chefann
    16 years ago

    Thanks kitova: I suppose we should give it one more shot. Looking over the arborists proposal right now, and I do see where they are scheduled to spray it again in the fall with horticultural oil. My guess is that it will be the oil you have recommended (although I have never heard of a neem tree...that is a new one for me!) The tree is too large at this point to wipe down. I appreciate the advice and am so glad I found this website. We have a big yard with lots of trees and many gardening "issues" !!!

  • kitova
    Original Author
    16 years ago

    hi chefann, i'm glad to hear it. we have lots of trees too and also lots of gardening "issues"! it sometimes makes me want to pull my hair out! but nothing ventured nothing gained, it's always amazing how much you learn and appreciate once you have you little bit of green to take care of..

    neem oil is just one of the oils you could use. i found a link about horticultural oils that might be useful: http://ipmofalaska.homestead.com/files/hortoils.html

  • rhizo_1 (North AL) zone 7
    16 years ago

    I promise you that your arborist will NOT be using neem oil, unless you specifically ask for it. Horticultural oil is not the same as neem.

  • goldis_sbcglobal_net
    12 years ago

    I need a person to spray the top of my 40 foot tall Magnolia tree for black scale.

  • mllrgrl2_hotmail_com
    12 years ago

    I have a 20 foot tall and 30 foot wide Magnolia which started weeping this year. A sticky substance began falling under the tree to the degree that we couldn't sit or stand under the tree for any amount of time. Thank God my boyfriend called the master gardener in our area and alerted us to the problem. We picked up the systemic and treated tonight and are planning to use the horticultural oil to spray it tomorrow. Any tips before we proceed?

  • ronalawn82
    8 years ago

    kitova, the most effective treatment would be Imidacloprid by injection. The treatment is best done by a professional - and a certified one at that!

    The injection puts a calibrated quantity of the insecticide into the sap of the plant which then becomes toxic to sap - sucking insects and bees! Drenching spreads the chemical unnecessarily into the environment. The only suggestion I can offer for the protection of these pollinators is to pluck the flowers before they open - a tough decision but a necessary one - in my opinion.

    The foregoing is based upon observation of the control of the "Spiral Whitefly" - a mini plague which swept up the gulf coast of Florida two or so years ago.

  • ronalawn82
    8 years ago

    kitova, I must condemn, in the strongest terms, the use of WD-40 for any other purpose than what is on the label. To further proclaim the unlawful treatment "...a permanent solution to killing magnolia scales..." is to do a great disservice to the participants who come here seeking solutions and those who seek to offer responsible pathways.

  • vbromero1952
    8 years ago

    WD 40 is mainly fish oil and said to be safe. Sheridan Nursery recommended the Bordo Copper Spray. I applied it yesterday on my magnolia tree and am still waiting for results. I checked it this morning and I don't see any significant change yet.

  • ronalawn82
    8 years ago
    last modified: 8 years ago

    kitova, this is the WD 40 to which I referred. Bordeaux Mixture is a Fungicide! LINK

  • ken_adrian Adrian MI cold Z5
    8 years ago

    I applied it yesterday on my magnolia tree and am still waiting for
    results. I checked it this morning and I don't see any significant
    change yet.


    ==>>. dead scale looks just like live scale..


    exactly what do you expect to find.. 24 hours later ...


    and what ron said about the efficacy of using a fungicide to kill scale


    ken

  • karlslapshot
    8 years ago

    how many times can you spray neem oil after waiting 7 days inbetween

  • gardengal48 (PNW Z8/9)
    8 years ago

    "WD 40 is mainly fish oil and said to be safe"

    WD 40 is NOT "mainly fish oil" - it is a petroleum based product. It is volatile and flammable and is not registered for use on any plant. It is not the same as using a horticultural oil and the legality of its improper use aside, it could very well cause damage to any plant to which it is applied.

    Neem can be used as many times as necessary to control insect problems, however you can limit the frequency if you apply during the appropriate life cycle stage of the insect in question. The most effective use of any horticultural oil as a control for scale is to apply when the insects are in their crawler stage. Begin by properly identifying the type of scale you have, then you can research its life cycle and determine when is the most appropriate and effective time to apply.

    "Sheridan Nursery recommended the Bordo Copper Spray. I applied it
    yesterday on my magnolia tree and am still waiting for results. I
    checked it this morning and I don't see any significant change yet."

    LOL! You may be waiting a long time to see any changes with your scale problem. As noted, Bordeaux mix is a fungicide and will have little to no impact on an insect problem. And even using a proper insecticide for the scale is unlikely to generate overnight results, particularly if you are not applying at the proper time for that insect.

  • mb_garden10
    8 years ago

    I have had a professional dual insecticide injected into my tree. I went from 4,000 bees (I counted them as my tree was humming) down to about 300 in 5 days. A second application 1 month later still has not relieved me of the last 200 or so bees. This is year 2 of fighting these ugly critters! A related question.... The honeysuckle that hits the ground turns my walkway black as all the plants under the tree too.

    What is the best way to wash the plants of this ugly honeysuckle. I have sprayed them multiple days with water and that helps some but the leaves on many are just covered in black. I have way to many to use a spong and wash them individually, is there a soap I can use?

    I have a 30x40' tall tree. It's sick to stand under it and I am still afraid of people getting stung by the drunk bees. Funny my bee guy laughs at the bees they really do act drunk.... they don't care about anything you can even hold the bees they just want more honeysuckle and dont care about anything else.

  • gardengal48 (PNW Z8/9)
    8 years ago

    You are trying to rid your plants of bees?? Please, please don't do that!! Bees are essential pollinators - our agricultural industry hinges on them - and they are threatened enough already by various environmental factors.....and not just honey bees. If you are allergic to bees, consider replacing the bee-attracting plant with something that doesn't but do not try to kill them off.

    And are you sure these are bees and not hornets or wasps? From the rest of your post, it appears you have been infested with some type of sucking insect that excretes honeydew (not honeysuckle) and wasps and hornets are highly attracted to this sweet substance, whereas bees are prefer actual plant nectar but will feed on honeydew if nothing else available.

    It is a mold - sooty mold - that grows on the honeydew that causes the black discoloration. It is difficult to remove just by hosing down with water. Some sources suggest a liberal spraying with insecticidal soap or even diluted dish soap and leaving it in place for awhile will help to loosen the mold which can then be more easily hosed off.

    But your best way of controlling both the bees/wasps/hornets AND the honeydew and sooty mold is to control whatever sucking insect is causing it in the first place. Have you identified what that might be?

  • rhizo_1 (North AL) zone 7
    8 years ago

    GG, I'm hoping that there's a language problem here. I'm wondering if mb is talking about the bees and wasps after the honeydew from the scale insects. The systemic pesticide has been killing the scale, thus reducing the amount of honeydew equals fewer wasps, etc.

    At least, I HOPE that's what he means, lol! If not, we may have to spank him.

  • mb_garden10
    8 years ago

    No spanking! Not in this day and age :-)

    No I am NOT killing the bees, although someone suggested spraying insecticide into the tree... I yelled NO at them!!! Just trying to stop them from swarming into my tree all day long. They just need to be pollinating flowers, other trees, etc. vs. ugly honeysuckle. The benefit is the immediate neighbors are getting bees from my trees as they leave....

    I have magnolia scale and an arborist is actively treating it... It has been a month and the scale is not all dead yet. We still have a few spots where it is still dripping honeysuckle.

  • mb_garden10
    8 years ago

    I will try a watered down dish soap that does not have a degreaser, and see if that helps the plants leaves. The dead scale has not dropped from the tree yet either, which I was told it would. Or do I need to use a high powered spray hose to dislodge them?

    This is what I have...


    Thetreegeek - Magnolia-scale

  • ronalawn82
    8 years ago

    kitova, "Funny my bee guy ...." "I have magnolia scale and an arborist is actively treating it ...." I infer that the poster has two professionals treating a magnolia tree that is infested by a scale insect. I trust that each professional knows what the other is doing.

    It might not make much difference; but other species of scale can be present - "Numerous pests occasionally prove problematic on magnolia, including species of armored scales like the California red, greedy and oleander scales and the soft tuliptree scale." SOURCE

    "The absence of foliage makes winter a good time to observe the large brown shells on twigs ...." Good Source By regular inspections, you can minimize the damage in the future.










  • danvauvh46
    7 years ago

    Update:

    Last summer I used WD-40 to kill the magnolia scales on my tree. Many posters here were understandably bothered by this. I just want to say that the scales remain dead and gone and my tree is doing well. All scales are gone. The bark in some spots is darker where I sprayed and the spray has impacted the bark by drying it out and cracking the bark in some areas. However, like I said in my previous post, the tree would've died anyway because the infestation was so bad and the wasps were terrorizing us just outside my front entrance. The tree has rebounded nicely, the flowers have bloomed and the leaves have all come out. If you are looking for a permanent solution and have had it with horticultural oils and other concoctions, give it a try. I'd also Recommend using the straw that comes with the WD-40 to minimize overspray and wear a mask and safety glasses. You can always just try a test patch on a few scales first to see for yourself if this solution is right for you.

  • kimmq
    7 years ago

    WD-40 is a moisture displacing lubricant meant to aid in preventing rust on garden tools but not as something to kill off problem insects. The manufacturer of the product does not recommend that use, and neither should anyone else.

    Will the product kill scale? Sure, and a lot of other things as well. It is not meant to be used as a pesticide.

    kimmq is kimmsr

  • Ttbm Ttbm
    7 years ago
    last modified: 7 years ago

    A definitive solution for my magnolia scale infestation:

    My 32 yr-old magnolia started to have scale infestation 6 years ago and I have tried many approaches mentioned in the internet including Bayer's systemic treatment, but all to no avail. There were years I had to trim off over half of the infested branches, and then dislodged whatever scales left with water pressure washer, half a dozen times over the summer--thankfully, the tree is only about 14-ft tall. Still, it was a losing battle and I wasted much time/money in it.

    In desperation, I tried another approach this year, willing to sacrifice the tree if necessary. Just about after blooming and before the leaves appear, I thoroughly sprayed the tree with a concocted solution composed of weldbond glue diluted with water, six parts of water to one part of weldbond in volume, and mixed in with horticultural oil per recommended proportion. Weldbond is known to be non-toxic and environmentally friendly, and so it's worth a try.

    Now, we're in early July, and I'm ecstatic that the leaves/branches are a lot denser that previous years, and that I found only 3 scales in one of the scars left by a cut off branch. Apparently, I missed spraying this spot!

    Here is my hypothesis of how this process works. Diluted weldbond solution dries fairly quickly--in less than an hour--and thus will likely entomb non-moving small particles such as insect eggs and overwintering nymphs. Well, it worked beautifully, but I am not sure if horticultural oil has any contribution to it.

    In the fall, after the leaves fall off, I'll spray this weldbond solution once again for a complete extermination.

  • Louise May B
    7 years ago
    last modified: 7 years ago

    gardengal48 and danvauvh46 - Petroleum oil is specifically marketed here in Australia for exactly this concern. It's called "White Oil" and it's active constituent is Petroleum Oil. It is a "Plant Insecticide & Leaf Shine", recommended specifically for : Aphids, Mealy-Bugs, Red, White Wax and certain other scales (not San Jose Scale), Sooty Mould, Spider Mites, White Fly and White Louse.

  • gardengal48 (PNW Z8/9)
    7 years ago

    Hhmmm - according to this AU fact sheet, 'white oil' is a vegetable based oil. No? In this country, white oil is a synonym for mineral oil, which is petroleum based. In a pinch, either could be used in place of a horticultural oil, which tend to be very highly refined and purified petroleum based oils (although plant based oils are becoming more common and popular but also highly refined (thinned)).

    But even hort oils are not very effective against any armored scales unless they are applied at the appropriate life stage of the insect.

  • Eli Gray
    6 years ago

    danvauvh46, Can you give us an update? It has been another year since your last update. I have a magnolia with scale. Had a number of arborists come out, basically $300 per year to control (bush is small, only about 7 feet tall), with no guarantee of eradication. Not going to happen. So tree either dies or gets the WD40 treatment for about $1 worth of the stuff. After you spray them, how did you know when they die? Do they fall off? They basically just look like mold, so not sure how you would know unless they fall off.

  • danvauvh46
    6 years ago
    last modified: 6 years ago

    @EliGray

    Hi Eli,

    When I sprayed the scales they loosened their grip (I'm assuming die) and fall off or you can spray them off with the hose.

    You're correct, it's been 2-3 yrs. since I started spraying WD-40. The scales came back in less numbers last summer and I sprayed them again. I sprayed conservatively because too much will dry out and split the bark. The following summer (this summer) I have been unable to find any scales. The tree is growing very well. It's about 12ft now and grows full. No more black drops of scale honeydew (secretion) on my patio and no more wasps. I'm very happy. My only problem now is how to control the growth. The tree is getting too big. I'm not familiar with pruning a magnolia. I'll have to do some research.

    Like I've said before, I understand the hesitation and environmental concern of some here in this forum when it comes to using WD-40. However, I was at the end of my rope with the scales and wasps. I don't claim to know what WD-40's active ingredient is. All I can tell you is that it worked for me. Try a test patch and see for yourself. Of course the choice is yours. Best of luck which ever way you decide to go.

  • Gaby C
    5 years ago

    danvauh46


    and where did you sprayed the tree? My tree is very tall or do you just spray the trunk? Approximately how many w-40 cans did you used?

  • danvauvh46
    5 years ago

    Try your best to only spray the scale bugs not the tree. If you spray too much onto the branches, it can cause the bark to crack and split however my tree has recovered and remains scale free. It took about 2 summers to get rid of them all. The idea is to use the straw to aim the spray at as many bugs as you can but try your best to keep the spray off the branches/trunk as much as possible. Of course some spray will drip onto branches but try your best not to.

  • sesvulcan
    3 years ago

    My 20 ft magnolia tree became heavily infested with magnolia scale. I did not treat it the first year as it was minimal and I hoped it would just go away. The second year it was heavily infested and I sought help from local nursery. I applied the neem solution around the base of the tree as advised and as directions recomended during the appropriate time. A second neem treatment was required some time later. I also drastically trimmed it back quite severely and manually scraped off all the bumps with a loose branch till I could see no more of them. It has been a couple years now and have seen no more evidence of scale but am still being vigilant. My tree is full and healthy but has not yet rebounded as blooming is minimal and is not anywhere near what it was. This year shows an abundance of blooms and am hoping for the best. I do fertilize with tree spikes. Is there a recommended tree fertilizer that may help with blooming? Thanks

  • ken_adrian Adrian MI cold Z5
    3 years ago

    tree spikes are useless ...


    if you fert your lawn ... that should be good enough ...


    ken

  • iKats
    3 years ago
    last modified: 3 years ago

    Hi all - we recently planted 4 30 gallon southern magnolias. They all looked good when planted. Then we noticed that one of them began to have wilted leaves. Over a week all leaves became wilted but not dry so they aren’t falling off. Our yard guy said to water it more, which we did, right before it completely wilted. Then he came out and said the roots were in the water and we should water less. Anyway, we have been very careful with watering but it is still wilted. And then today I found the attached white / grey speckles on the Underside of the leaves of this tree. Surprisingly, this was also found on one of the healthy tree leaves, on which the leaves aren’t wilted. I don’t want for the trees to die so any advice on what this is and how to treat it would be appreciated. also in the last couple days we have put in jobe’s spikes in the ground and also sprayed Bayer tree and shrub insecticide around the trunks.


  • ziyouzizai
    3 years ago
    last modified: 3 years ago

    Ttbm Ttbm,

    how is your Magnolia tree now since your weldbond concoction a few years back? Did you have to reapply ever since?


    danvauvh46,

    Beautiful tree, by the way and how is your Magnolia tree doing now? Can I please ask you when do you apply the WD40? Do you do it after it blooms, mid season, and in the fall, or just whenever you see the crawlers?


    The leaves of my two Susan Magnolia started falling this weekend in Chicago and I see white oval discs on the branches, again. The trees are about 8 ft tall. I had trimmed off the scale infested branches last season and both trees put on a great show this year with very lush leaves. I did not think the scales return until now. It was really hard to see given all the leaves! Two years ago, the smaller of the three Susie's had to be dug out due to scale. I really don't want to lose these two other trees to scales again :( forecast says we'll be in the 60s for three more days and then back to the 30s. Hoping to do anything that can help the trees now....