best treatment for magnolia scale NOW

kitova(z6 NJ)May 2, 2006

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.

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ginkgonut(4)

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

    Bookmark   May 2, 2006 at 8:35PM
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ginkgonut(4)

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

    Bookmark   May 2, 2006 at 11:49PM
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kitova(z6 NJ)

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.

    Bookmark   May 3, 2006 at 11:02AM
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kitova(z6 NJ)

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

    Bookmark   May 3, 2006 at 11:22AM
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rhizo_1 (North AL) zone 7

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?

    Bookmark   May 3, 2006 at 11:23AM
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kitova(z6 NJ)

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

    Bookmark   May 3, 2006 at 11:29AM
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ginkgonut(4)

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

    Bookmark   May 3, 2006 at 12:21PM
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kitova(z6 NJ)

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?

    Bookmark   May 3, 2006 at 2:07PM
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chefann

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?

    Bookmark   June 19, 2007 at 1:00PM
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kitova(z6 NJ)

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..

    Bookmark   June 19, 2007 at 1:56PM
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chefann

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" !!!

    Bookmark   June 20, 2007 at 9:39AM
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kitova(z6 NJ)

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

    Bookmark   June 20, 2007 at 10:08AM
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rhizo_1 (North AL) zone 7

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.

    Bookmark   June 20, 2007 at 11:03AM
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goldis_sbcglobal_net

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

    Bookmark   June 22, 2011 at 12:43PM
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mllrgrl2_hotmail_com

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?

    Bookmark   June 23, 2011 at 10:12PM
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