Sunday, April 26, 2009

Landscape - Scale Insects: Elongate Hemlock Scale

This is the 18th in a series on scale insects in the landscape. This post is on the Elongate Hemlock Scale. Information is from the University of Maryland.

Elongate Hemlock Scale (Fiorinia externa Ferris), Family Diaspididae

Plants Damaged: Hemlock is the predominant tree we see this scale damaging in Maryland but it also attacks spruce, pine and Taxus yew.

Damage Symptoms: This scale feeds on the needles and leaves of infested plants. Feeding causes chlorosis of foliage and needle drop and dieback of the plant.

Life cycle: There are two generations per season of hemlock elongate scale. Crawlers are active in May. The nymphs settle on the foliage of the plant where they spend their whole life cycle. The generations overlap for this scale which makes it somewhat challenging to control. Crawlers can be produced throughout the summer and into the fall.

Monitoring: Examine needles on the undersides for the presence of this scale

Control: Distance can be applied to the crawlers. Horticultural oil can be used to control overwintering females. Soil applications of dinotefuran (Safari) are effective in control of this scale.

Information from "Scales Commonly Encountered in Maryland Landscapes and Nurseries" by Stanton Gill, Extension Specialist in IPM for Nurseries and Greenhouses,and Suzanne Klick and Shannon Wadkins, Technicians, Central Maryland Research and Education Center University of Maryland Cooperative Extension.

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