Hemlock Elongate Scale

Fiorinia externa

Elongate hemlock scale, Fiorinia externa, is an armored scale that is a common pest of Eastern and Carolina hemlock in the Eastern United States. This scale pierces the underside of the needle with its mouth parts and removes fluids from the needle. Trees that are severely infested will exhibit needle yellowing or dropping, thinning canopy, and eventual death.

Treatment Strategy

The treatment of hemlock elongate scale can be challenging because timing is so critical.  In most regions, crawlers are active in the late spring through mid summer, making soil-applied systemic insecticides that last for the season the preferred choice for most professional arborists. These products also have the advantage of controlling another common insect of hemlocks, hemlock woolly adelgid.

Purchase Hemlock Elongate Scale Treatments Now!

Hemlock Elongate Scale Treatment Option 1

Controlling hemlock elongate scale can be difficult with spray applications, because most products only control active insects for 14 days. Several applications of a product such as Up-Star® Gold, applied at least once per month, are typically needed to get an infestation under control.

Application Method – Foliar spray

DIY Equipment/Product Needed:

• Up-Star® Gold

• Hand pump sprayer with wand

• Gloves

• Safety glasses

Hemlock Elongate Scale Treatment Option 2

Fortunately, current technologies have provided us with soil-applied systemic treatments that can last throughout the growing season. One application of a product such as Transtect will provide approximately 90 days of control for hemlock elongate scale by moving through the tree where the insects feed – the conductive tissues. Transtect™ applications can be made to the soil in the spring and provide control for the majority of the scale’s life cycle.

Application Method – Soil drench

DIY Equipment/Product Needed:

• Transtect

• Soil drench kit

• Diameter tape or measuring tape

• Watering can

• Gloves

Hemlock Elongate Scale Treatment Option 3

None

Hemlock Elongate Scale DIY Kit

Option 1

Application Method – Foliar spray

DIY Equipment/Product Needed:

• Up-Star® Gold

• Hand pump sprayer with wand

• Gloves

• Safety glasses

Option 2

Application Method – Soil drench

DIY Equipment/Product Needed:

• Transtect

• Soil drench kit

• Diameter tape or measuring tape

• Watering can

• Gloves

How Is It Spread?

Hemlock elongate scale has one to two generations each year. Females deposit eggs under their waxy coverings throughout spring and early summer. Eggs hatch in 3-4 weeks and crawlers move to new growth to feed on the underside of needles for 3-4 weeks. Once mature they either lay eggs or can overwinter as an adult. The staggering life stages of elongate scale means that crawlers are active throughout the spring and summer.

Susceptible Trees

The primary hosts are Easternand Carolina hemlocks, but northern Japanese hemlock, fir, and spruce can also be affected by hemlock elongate scale.

Symptoms

• Yellow foliage that drops prematurely giving the tree a thin appearance.

• Yellow banding may occur on the upper surface of infested needles.

Dieback of major limbs starts at the bottom of the tree and progresses upward.

• Death of the tree can take as little as 10 years.

Lookalikes

None

Related/Similar Problems

Hemlock woolly adelgid

Timing

Spring-Early summer

Urgency

High

Risk of Spreading

Moderate

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