Extension’s garden help line is a must for plant lovers

Posted: July 26, 2014

Special to The Winchester Star

Winchester — Local residents are enthusiastically using the Frederick County Green Help Line to answer their gardening questions.

And phone calls, walk-ins and emails are already surpassing last year’s total, according to Mark Sutphin, Frederick County associate Extension agent.

This year’s number of visits, calls and e-mails tally 112 since early April. Last year’s total for the year was 150 to 175, and more questions are expected before the gardening season ends — typically after the first hard frost in mid-October, Sutphin said.

“The Green Help Line, staffed by volunteer Master Gardeners, definitely provides an important service, and local residents are taking advantage of this free program to have their gardening questions answered,” he said.

The Green Help Line typically receives about 10 questions a day during the summer months, but has had as many as 30 in one day, he said.

The emerald ash borer is one pest that many residents are calling about, he said.

It has been identified in northwestern Frederick County since spring 2012, and a large infestation has been found in forested areas. It is also being discovered in residential areas across the region and has been found in young and mature ash trees.

Residents may not always see the beetle to identify its presence on an ash tree, said Sutphin. Instead, they may see a D-shaped exit hole, about the size of a pencil.

Dieback may be seenin the canopy and sucker growth on the main stems, branches and trunk, he added, along with woodpecker activity on the tree — which indicates that the tree is under stress.

Treatment includes using a systemic insecticide with the active ingredient imidacloprid, he said.

This is most effective one to two years prior to infestation and can be applied by soil drench, foliar spray or trunk injection. As with all pesticides, users should read and follow the label’s directions.

If the outer layer of bark on the ash tree has begun to slough off in some places, it is typically too late to save the tree, Sutphin said.

Leyland cypress are also generating many questions from homeowners, he said. The area experienced extreme cold and oscillating temperatures during the winter, which caused winter desicca tion among boxwoods, Leyland cypresses and other evergreens.

Most of the plants affected should be showing signs of regrowth by this point, he said.

To minimize damage in the future, homeowners should ensure that plants receive adequate water during the growing season and irrigate plants deeply before the ground freezes, if conditions have been dry, said Sutphin.

The area is also seeing Seiridium canker on Leyland cypress, and the first noticeable symptom is scattered branch dieback.

No effective treatment for this disease is available, other than pruning dead branches to healthy tissue, he said.

Leyland cypress is predisposed to this disease by water stress, so the best prevention is to water the trees during times of drought, he said.

The Virginia Cooperative Extension does not recommend planting Leyland cypress en masse in landscapes in the future, he said. They were planted by homeowners in the area because they grow quickly and provide a useful screen and wind-break.

However, because they were overplanted, “we are also losing them en masse here,” he said. Better choices include green giant arborvitae, hollies and spruce trees.

“It’s always best to have a diverse landscape rather than one species,” Sutphin said. “We are seeing more invasive pests and species come to this area, and if a homeowner loses out to a pest, they can lose their entire planting.”

Spider mites are also being reported in dwarf Alberta spruce, arborvitae and on roses and other landscape plants, he said. It’s a seasonal issue that can be treated with a miticide or insecticidal soap.

One common complaint heard by gardeners about their tomato plants is that they are withering from the bottom up, said Sutphin.

This is likely the result of a fungal disease called septoria leaf spot, common in areas with high humidity. Symptoms include small circular brown leaf spots on the lower leaves, eventually causing the entire leaf to turn brown — and the infection moves up the plant, he said.

Regular application of a registered, preventive fungicide will control the disease, as will spacing plants adequately and staking or caging plants to promote air circulation help to prevent infection, Sutphin said.

For more answers to gardening questions, visit the Frederick County Extension Office at 107 N. Kent St. (second floor) or email greenhelpline.frederickco@gmail.com or call 540-665-5699.

— Teri Merrill is a Master Gardener with Virginia Cooperative Extension.