Magnolia Scale

jmccafferty · 15th July 2009, 11:30 AM

I have had problem over the last few years with what a few local (Detroit area MI) tree services have called oyster shell scale on my magnolia tree. Two have sprayed, and it keeps coming back. The last guy I had out said I will never be able to get rid of it, only control it, and he said to cut it down.

I would like to keep the tree

, but I have no desire to fight this on an anual basis. Is it true that it will never go away? Is there something I can do to treat in at a reasonable cost? What conditions bring about this pest?

Thanks for your time.

Eric Frei · 16th July 2009, 12:55 AM

How big is this tree?

Cannot you spray it yourself?

Seems May June is the typical time they infest, apparently you cannot do much till these buggers head for the banquet as the are shielded under an amour plate scale.

MSU Landscape Alert newsletter

Quote:

Between 40-150 small, grayish white eggs will be found under each female scale in the spring. Crawlers are active in late spring, usually two to three weeks after apple bloom. The crawlers move about for a few hours before settling on the bark and inserting their long, hair-like mouthparts to begin feeding. The formation of their waxy scale coating begins soon afterwards. There appears to be a single generation per year in Michigan.

Like other “armored” scales that overwinter in the egg stage, dormant oils applied in the spring or fall are not effective in controlling oystershell scale. “Soft” scales overwinter as exposed nymphs which are susceptible to dormant oils. Control of armored scales requires insecticides be applied at the time the crawlers are active, which for oystershell scale is in mid- June. The presence of crawlers can sometimes be determined by sharply tapping an infested twig or branch over white paper. Crawlers are often orange, brown or purple and appear as moving specks of dust. Because of their waxy protective covering, other stages of scales are not readily controlled by contact insecticides. Insecticide sprays will not reach crawlers that have settled under old scales. Besides overwintering habits, another difference between armored scales and soft scales is that the soft body of the armored scale insect can be easily separated from its scale covering (see photo). In soft scales, the body of the insect and its scale covering are firmly joined and cannot be separated.

In general, controls will be more effective if heavily infested twigs or branches are pruned out. In some cases, large sized scales can be scrubbed off with a stiff brush. Horticultural oils offer a safe alternative to traditional contact insecticides and are especially good choices for sensitive areas, such as where people will be present soon after treatment. Because of their short residual, they help to conserve beneficial species. They are very effective against both active and settled crawlers.

15th July 2009, 11:30 AM	#1
jmccafferty I'm new here so be nice Join Date: Jul 2009 Location: MI Posts: 1	Magnolia Scale I have had problem over the last few years with what a few local (Detroit area MI) tree services have called oyster shell scale on my magnolia tree. Two have sprayed, and it keeps coming back. The last guy I had out said I will never be able to get rid of it, only control it, and he said to cut it down. I would like to keep the tree, but I have no desire to fight this on an anual basis. Is it true that it will never go away? Is there something I can do to treat in at a reasonable cost? What conditions bring about this pest? Thanks for your time.

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