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Pest Facts: Hemlock Woolly Adelgid (HWA)

October 28, 2019

Just visit a Western North Carolina forest to see how much destruction this non-native invasive insect pest has caused—and is still causing—on the native Carolina hemlocks (Tsuga caroliniana) and Eastern hemlocks (Tsuga canadensis)! After our recent rains, this is a good time to treat your hemlocks if you see a white cottony substance on your hemlocks.

Hemlock Woolly Adelgid

History

  • HWAs were discovered in Shenandoah National Park in northern Virginia in 1988, likely when crawlers clung to the legs and feathers of migrating birds, such as the black-throated green warbler and solitary vireo that visit or nest in hemlock trees.
  • HWAs were discovered on hemlocks in North and South Carolina in late 2001 and early 2002.

HWA (Adelges tsugae) Life Cycle:

  • HWAs hatch from eggs and then go through a crawler stage—almost invisible to the naked eye. These crawlers cannot fly on their own but can drift in the air from tree to tree, and cling to the legs and feathers of migrating birds.
  • After settling on host trees, the HWAs insert a bundle of mouthparts at the base of a needle and spend the rest of their lives—a few months—sucking nutrients out of the tree.
  • The name “woolly” comes from the fact that adult HWAs are covered with a protective white fluff once they settle.
  • The HWA goes through two generations a year (one in March and one in October in Western North Carolina) and each female—even without being fertilized by a male—can lay between 100 to 300 eggs.
  • This reproductive process is called “parthenogenesis”—the offspring are genetically identical clones of their mother.

Controls

Chemical: Registered pesticides containing imidacloprid or dinotefuran are the most effective chemical treatments for control of HWAs. These are applied as a soil injection or trunk spray. These insecticides are water soluble and move into the tree’s vascular system along with water. Dinotefuran has a faster uptake, but imidacloprid has a longer residual protection. Control of HWAs using imidacloprid can last for 4-5 years. Dinotefuran may require retreatment within 2 years.

Biological:

The species that has so far shown the most promise as a biological control agent is Laricobius nigrinus, a predator beetle native to the Pacific Northwest. L. nigrinus is active from October to March; both adults and larvae will consume all stages of HWAs: eggs, nymphs and adults.

After exhaustive evaluation in quarantine labs, it was cleared by the USDA for use as an HWA biocontrol in the eastern United States in 2000 and has been released in NC since 2003.

Original Article by Glenn Palmer, Extension Master GardenerSM Volunteer, Revised by Bob Wardwell, Extension Master GardenerSM Volunteer

Hemlock Restoration Initiative https://savehemlocksnc.org/

National Park Service Great Smoky Mountains Hemlock Woolly Adelgid

https://www.nps.gov/grsm/learn/nature/hemlock-woolly-adelgid.htm

University of Massachusetts HWA Fact Sheet https://ag.umass.edu/landscape/fact-sheets/hemlock-woolly-adelgid

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Categories Invasive Insects, Pest Management, Trees Tags Biological Control, Hemlock Woolly Adelgid, insects, pest control, trees

Firewood: Garden Pest Carrier

February 11, 2019

Chimney Fire! As someone who used firewood to heat my home for twenty years, I used to think that was all I had to worry about. Now I know how wrong I have been!

Firewood provides an avenue for forest diseases and insects to invade. Most of the insects that spread these diseases can move between 5 and 10 miles per year.  With human assistance, though, they can move hundreds of miles a day—hitchhiking on firewood you transport in your vehicle!

Staying warm by the fire

Insect Pests in Western North Carolina

  1. Emerald Ash Borer (Agrilus planipennis—EAB) is a green beetle in the Buprestid family. It is native to north-eastern Asia and feeds on white ash (Fraxinus Americana) and green ash ( pennsylvanica) in WNC. Females lay eggs in bark crevices on the trees, and larvae feed underneath the bark of ash trees, emerging as adults in 1 to 2 years. First detected in Michigan in 2002, EAB spread northeast to Vermont, south to Georgia, and west to Missouri. The entire state of North Carolina is under USDA Animal Plant Health Inspection Service (APHIS) quarantine for EAB.

    Emerald Ash Borer
  2. Walnut Twig Beetles (Pityophthorus juglandia—WTB) are very small—1/16 inch (1.5 mm)—reddish-brown bark beetles in the Curculionid family. In NC, they attack black walnut (Juglans nigra), boring through the outer bark and into the phloem of trees’ branches and main stems. With the help of a fungus, Geosmithia morbida,they bring Thousand Cankers disease. In 2012, a Walnut Twig Beetle adult was captured in a trap in Haywood County.

    Walnut Twig Beetle
  3. Other insect pests under quarantine in North Carolina, but not in the Western region of the state, include European gypsy moth (Lymantria dispar), and the red imported fire ant (Solenopsis invicta).

What can YOU do?

  • Respect any quarantine requirements regarding firewood movement.
  • As of March 1, 2015, only heat-treated firewood bundled and certified by the USDA or a state agency may be brought into the Great Smokies Mountain National Park and the Blue Ridge Parkway. Campers may collect wood found in the park to use in campfires.
  • If you have to move firewood over a long distance, make sure it is packaged, heat-treated firewood with a USDA APHIS heat treatment seal, or a state-based (such as a State Department of Agriculture) heat treatment seal.
  • Burn any firewood you collect within a 50-mile radius of its origin.
  • If you buy firewood and don’t burn it all, DO NOT take it home with you or to your next destination!

The use of firewood, a renewable resource, for heat has many advantages.

Firewood Basics

  • Firewood is sold in what is commonly called a “cord”. This is defined in North Carolina as equal to the amount of cut and tightly stacked roundwood that can fit inside a container that measures 4 x 4 x 8 feet, or 128 cubic feet.

    Split and stacked firewood
  • Cut AND split firewood typically reaches its driest state after 9 or more months, to include one summer. During this period, the wood should reach a moisture content of less than 20%.
  • Stack firewood with the bark facing upwards to allow water to drain off, and any standing frost, ice, or snow off the wood surfaces.
  • Be aware that storing wood close to a dwelling or inside for an extended period increases the likelihood that insects, such as termites, can become established indoors.
  • Each species of wood has a different potential for providing heat. This is expressed in British Thermal Units (BTU).

Article by Bob Wardwell, Extension Master GardenerSM Volunteer

Invasive Species and Firewood Movement https://www.ncforestservice.gov/forest_health/pdf/5%204_WUI_CR_NNISandFirewood%20Movement_wNCFSLOGO.pdf

Preventing Firewood Movement https://www.ncforestservice.gov/forest_health/pdf/5%205_WUI_CR_PreventFirewood%20Movement_wNCFSLOGO.pdf

Comparison of firewood heating values

https://outreach.cnr.ncsu.edu/woodworkshops/documents/ChimneySweepsWoodBTUChart.pdf

More on Firewood Insects

https://outreach.cnr.ncsu.edu/woodworkshops/documents/FirewoodInsects.pdf

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Categories General Gardening Tags emerald ash borer, Firewood, Thousand Canker Disease, trees, Walnut twig beetle

November Garden Tasks to Save Time and Money

November 3, 2014

November 1st brought first frost, first freeze, and first snow, all in one morning! Winter is on the horizon, but there are still some essential gardening tasks to be done.

Soil tests save time and money! Your lawn and gardens will grow better, and you will not waste money on unneeded fertilizer. Free soil tests are available for samples received in Raleigh by November 25th. After that, they will be $4 per sample. Soil test boxes and instructions are available at the Extension office. For more information about soil testing, go to http://content.ces.ncsu.edu/a-gardeners-guide-to-soil-testing.pdf

Regardless of soil test results, now is the time to fertilize your lawn with one pound of slow-release nitrogen per 1000 square feet. Lime may be applied if a soil test indicated pH below 6.0. Keep leaves off your lawn, and save those leaves for composting.

Autumn leaves

Any remaining diseased foliage should be removed and bagged for the landfill. Perennials can be divided and dead foliage removed. Remember that wildlife needs shelter for the winter. Often this is dead foliage and fallen evergreen branches, so consider leaving non-diseased foliage in place until spring. The birds, bees, and other small critters will appreciate it.

Clean and oil your garden tools and equipment so they will work better and last longer.

For the best return on your investment, now is the time to plant trees, shrubs, ground covers, and spring-flowering bulbs. Roots will grow through the winter, and plants will do better when summer heat returns.

Article written by Diane Puckett, Extension Master Gardener Volunteer.

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Categories Seasonal Chores Tags fall garden chores, fertilizer, garden tools, leaves, lime, soil test, trees

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