White froth on hemlock needles means a pest has invaded


April 02, 2000

Q. I have several hemlocks in front of my house that have little bits of white froth all over the needles. Is this natural or some sort of pest I should be concerned about?

A. The white waxy masses are the ovisacs (containing the adult females) of the hemlock wooly adelgid. These are aphid-like sucking pests that are a serious pest of eastern and Carolina hemlock. Heavy infestations can weaken and kill mature trees, particularly when they are stressed (e.g. growing in poor soil on a dry site). Spray trees with ultra-fine horticultural oil in late June or early July when the crawlers emerge from the ovisacs and begin to feed on needles. Follow up with a dormant oil spray between next November and March. Be sure to water your trees during a drought.

Q. I hang a hummingbird feeder every spring from my deck, but this year I want to plant annuals and perennials they like. What should I look for in the garden centers?

A. Some good choices are cardinal climber (annual), cardinal flower, columbine, bee balm, bleeding heart, daylily and hollyhock (all perennials).

Q. I love fresh onions out of the garden. When I tried to grow transplants, the plants got tall growing under lights and I was scared to cut them back. Is it better to just start seeds outdoors or start from transplants?

A. When possible, start with transplants. Bulb onion plants grow best during cool spring weather and the bulbs size up best during hot summer weather. So planting transplants will give you a head start and larger bulbs. Seed should be sown indoors 6-8 weeks before the last expected frost. The plants can be clipped with no harm done. Harden off pencil-size transplants and set them out two weeks before the last expected frost.


1. Remove the silken webs of the Eastern tent caterpillar from wild cherry and crab apple trees. Infested branches can also be pruned out.

2. Work well-rotted manure or yard waste compost into vegetable and flower beds. Never add fresh manure to vegetable beds in the spring.

3. Divide and replant overgrown perennials. This will help rejuvenate the mother plant.

Garden tips are provided by the Home and Garden Information Center of the Maryland Cooperative Extension . For additional information on these questions, or if you have questions of your own, call the center's hot line at 800-342-2507, or visit its Web site at www.agnr.umd.edu/users/hgic.

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