February 10, 2013

Maine Gardener: Progress (or not) on pest front

By TOM ATWELL

The hemlock wooly adelgid is progressing farther in Maine, but the damage has not been as severe here as it has been in warmer regions of the country, state horticulturist Ann Gibbs told the Maine Landscape and Nursery Association in January.

The presence is limited to coastal areas from York to Sagadahoc counties.

"In Maine, it is not killing trees really quickly," Gibbs said. "It's really been killing trees in the Smokies. It's a sad sight."

The pest -- an aphid-like insect that leaves white, wool-like wax filaments under the hemlock's branches -- can be controlled quite easily on home landscapes, but chemical treatments are not practical in the state's forests, Gibbs said. 

"With the milder winters we have been having, it has spread fairly quickly along the coast," she said.

She said that the state has released two biocontrols -- beetles -- that might control the adelgid. The two beetles are Sasajiscymnus tsuga from Japan and Laricobius nigrinis from the Pacific Northwest.

Gibbs said they both have survived since being released in Maine, but it is too early to know if they are having any effect on controlling the adelgid.

Hemlocks also have a new problem: elongate hemlock scale, which can harm fir trees as well. This scale causes a yellowing of the needles, scale coverings on the underside of the needles, and premature needle drop.

The scale was found in southern Maine and probably came in on nursery stock from the Carolinas.

"When it works with the adelgid, it is three times as bad as when there is just one of them," Gibbs said.

THE EMERALD ASH BORER, Gibbs said, is getting closer to Maine, with the beetle showing up in several towns in Connecticut, and one beetle showing up in one trap in Massachusetts -- although scientists could not find an infested tree.

The emerald ash borer has just about wiped out ash trees around Michigan, and is spread mostly by moving firewood. Maine has banned bringing firewood into Maine.

The state will again set out traps trying to catch the emerald ash borer, with the effort supported by the state and federal governments as well at the Maine Indian tribes.

"The tribes are very concerned, because the ash is a sacred tree to them, very important in basket making," Gibbs said.

THE ASIAN LONGHORN BEETLE, which feeds mostly on maples, remains in the Worcester, Mass., area, and has not been spreading. But the state has some concerns about trees downed by Superstorm Sandy being chipped and sent to Maine.

The beetles supposedly cannot survive if the chips are cut 1 inch or smaller in at least two directions, but Gibbs said people might want some more research conducted before allowing such chips in Maine for use as fuel.

THE WINTER MOTH, which a year ago was a problem in Harpswell and Vinalhaven, was reported in 33 towns in Maine late last fall and earlier this winter.

While the moths show up from November through January, the worms hatch out in the spring and will damage a wide variety of leaves.

The pest will stay in the soil all summer, and will be moved in pots or when people do transplants. Some biocontrols are being studied.

BOXWOOD BLIGHT has hit Maine, but it has been learned only recently that the blight also will damage pachysandra, part of the same plant family and a popular ground cover in Maine.

Impatiens downy mildew was another topic, but I covered that two weeks ago.

MELNA AWARDS AND MORE

ROBERT BANGS of Windswept Gardens in Bangor won the Al Black Award for 2013, given by the Maine Landscape and Nursery Association for outstanding contributions to the horticulture industry.

Bangs started his company in 1972 as Robert Bangs Landscaping, and has expanded to include a full garden center as well as full landscaping. He has a regular television segment on WABI-TV in Bangor, and has been active in MELNA operations and committees.

Jake Pierson, nursery manager at Pierson Landscaping, a wholesale nursery in Dayton, won MELNA's young horticulturist award. He lives in Portland and is the son of Dale Pierson, the nursery founder.

Sara Tryzelaar of Greenbush won the Donglin Zhang Scholarship for students studying horticulture at the University of Maine, and Paul Bronder won the scholarship for students at Southern Maine Community College.

THE PORTLAND FLOWER SHOW, which will be held March 6-10 at the Portland Company Complex at 58 Fore St., is looking for volunteers.

Some are needed to put up posters before the show, but most volunteers are needed in four-hour shifts March 7-10. The shifts start as early as 9 a.m. and run as late as 7 p.m.

If interested, contact Kerry Ratigan at 615-6271 or ratigankerry@gmail.com.

Tom Atwell has been writing the Maine Gardener column since 2004. He is a freelance writer gardening in Cape Elizabeth and can be contacted at 767-2297 or at:

tomatwell@me.com

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