I have had several inquiries lately about tea scale management from nursery growers in eastern NC. This insect is a common pest in camellias and large leaved hollies (ex. Ilex cornuta or crosses with the same).
Nursery Management of Tea Scale on Camellias and Hollies
In smaller production sizes with short production times, this insect is not usually a problem. When grown in larger containers (7 gallon and up) or in field production over multiple years, populations build and leaf chlorosis caused by feeding becomes an issue. The challenge with management is that they feed on the lower surface of leaves making foliar application of insecticides difficult.
It doesn't take many years for populations to build since there are multiple generations a year. To learn more about the lifecycle review this Tea Scale Entomology Insect Note and its resource links. Tea scales have multiple generations from February to November and thus monitoring crawlers can be important to determining treatment timing with insecticides.
The following products are listed in the NC Agricultural Chemicals Manual for management of tea scale:
Most of these products will provide best results if applications are made when crawlers are present, so utilizing double sided tape on branches near where adults are present to monitor for them can be useful. Also periodically removing leaves and checking with a hand lens or dissecting scope to determine crawler emergence is another option. Acetamiprid does have translaminar systemic activity so if you can direct applications to the tops of infested leaves, that product will help reduce populations of scales on the lower surface. Azadirachtin, buprofezin and pyriproxyfen are insect growth regulators and must be used to target crawlers.
Dinotefuran is a systemic neonicotinoid that is effective and can potentially provide better population reduction when foliar application is difficult. It can be applied as a drench to container or field grown plants, as a basal bark spray, or in the field as a banded soil spray application. Check the label of products containing dinotefuran for more information on these treatment options.
After insecticide applications are made, since the covering does not disapear, you can determine how well applications worked by turning over the dark females as described in the fact sheet to determine if they are alive. As with most scale insects, growers need to be diligent with scouting and management of tea scale to avoid population buildup that might affect sales.
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