July 12, 2003
Saturday

Sitka, AK - Sitkans weren't the only ones who enjoyed last winter's mild weather and relatively few days of below-freezing temperatures.

The spruce needle aphid, a mite-sized insect that feeds on spruce needles, also took advantage of the mild winter.

"Aphids build up before the damage is detected, and in order to be effective, controls should be carried out before extensive defoliation has occurred."... Patrick Heuer, Silviculturist

According to Patrick Heuer, silviculturist for the Tongass National Forest's Sitka Ranger District, aphids are a periodic problem in Sitka and other coastal areas throughout southeast Alaska.

"For many trees in Sitka this will be five years of defoliation in six years," said Heuer. "Most of the trees defoliated will experience thinned crowns and reduced growth. Tree mortality, though uncommon, is possible among smaller spruce trees and the most heavily defoliated trees."

Spruce aphids can reproduce throughout the year and increase in numbers during mild winters. Aphid damage occurs during late winter and early spring, but is not readily noticeable until mid-summer when needles on infested trees turn brown and begin to fall off.

"This is what we are currently experiencing here in Sitka on many spruce trees," said Heuer. "Harsh winter weather is the most important natural control for spruce needle aphids."

Early detection is the key to help remedy the problem.

"After mild winters homeowners should expect aphid damage and must recognize the importance or early detection of the insects," he said.

"Aphids build up before the damage is detected, and in order to be effective, controls should be carried out before extensive defoliation has occurred," explained Heuer. "Careful and periodic examination of the needles, beginning in February after a mild winter is necessary to determine the presence of aphids. Aphids will first appear on the shaded portion of the lower crown and can be seen on the under side of the needles."

Treatments can help fend off the insects.

"When aphids are sighted a high pressure water spray or spraying will soapy water may dislodge many of the insects from the needles, but will need to be repeated often and works best on smaller trees," said Heuer. "Other treatment options including application of insecticide can be effective. Spring and fall fertilization also can help promote tree vigor and minimize tree damage."

For more information, including specific treatment options, call the Cooperative Extension Office in Sitka at 747-6065.

Source of News Release:

USDA Forest Service - Tongass National Forest
Web Site

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