Ask an expert: Tips for controlling woolly beech aphids –

Ask an expert: Tips for controlling woolly beech aphids

Gardening is in full swing and if you’ve got questions, turn to Ask an Expert, an online question-and-answer tool from Oregon State University’s Extension Service. OSU Extension faculty and Master Gardeners reply to queries within two business days, usually less. To ask a question, simply go to the OSU Extension website and type in a question and the county where you live. Here are some questions asked by other gardeners. What’s yours?

Q: There is some disgusting fungus growing under all the leaves on my little tree (it’s about 6 feet tall). I don’t know what this tree is. I need to know if tree can be saved and how to do so to get rid of gross fungus. – Washington County

A: Your tree is a tricolor beech, Fagus sylvatica ‘Tricolor.’

The fuzzy white stuff is not a fungus, but are woolly beech aphids (Phlaphis fagi). Because the tree is so small, you should be able to manage the aphids by yourself. These woolly aphids commonly afflict beech trees. They may return during most years.


  • Begin by using a harsh water spray to blast the aphids off the undersides of the leaves.
  • After the leaves dry, spray the aphids with direct hits of a commercial insecticidal soap. Read and follow the label directions, also repeat as needed.


  • Don’t use a homemade spray as it is likely to damage the tree.
  • Don’t use the commercial soap spray – or any other pesticide – if the temperature is, or will be, 85 degrees F that day.

– Jean R. Natter, OSU Extension Master Gardener Diagnostician

Could these weeds actually be shoots from a nearby tree? Ask an expert.OSU Extension Service

Q: I have these plants and have no idea what they are. It seems no one else does, either. If left alone they grow into little trees, I hate them. They are taking over my yard. I cut them down in their initial growing area, now there are sprouts everywhere. – Lane Counts

A: I would bet these tree sprouts are coming from the root system of the tree beyond your fence. I could not see the leaves of that tree, but usually it is a cherry or a plum that runs roots underground, which then sprout into new trees at all the nodes. Cherry trees have a very distinctive bark and leaves, plum a little less so. They are very invasive. You can dig a ditch on your side of the fence and cut any roots you see and then work at cutting out, not just down, the shoots. – Pat Patterson, OSU Extension Master Gardener

Plant strawberries in full sun for best production, say gardening experts.Beth Nakamura/Staff

Q: Is it possible to grow ‘Seascape’ strawberries from their seeds? – Washington County

A: It is possible; however, ‘Seascape’ is a hybrid. The ‘Seascape’ strawberry (Fragaria x ananassa ‘Seascape’) is a hybrid everbearing strawberry variety. Strawberry plants produce runners that put down roots and form new plants. You can propagate strawberries by planting the runners, from seeds or by the roots.

You can pot up the mother strawberry plant and wait for runners or stolons and put small mounds of dirt around the “daughters.” That will give the ‘Seascape’ strawberry.

However, since this is a hybrid, the seeds may not grow true to the ‘Seascape’ taste or size. To save the seed, grow the seeds into strawberry plants. Then wait until the strawberry is starting to become very mushy and dry the seeds from it.

Here is an article regarding starting strawberry seeds. – Sheryl Casteen, OSU Extension Master Gardener

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Q: This spring, we had to remove our paper birch trees because of the bronze birch borer. We are considering replacing them with a dogwood. When will be the best time to plant it? – Linn County

A: Here is an excellent publication detailing landscape trees and their care. You should be able to find the tree you like available at a nursery this fall. I don’t know which dogwood you are considering, but the Pacific dogwood and the western dogwood are both native to our area.

From the publication Selecting, Planting, and Caring for a New Tree, available in pdf or app:

“Plant shade and ornamental trees during the dormant season when there are no leaves on the tree. In western Oregon, plant trees between November and April. In eastern Oregon, there are two planting seasons: early to late fall (September to November) until the ground freezes; and in spring just after the ground has thawed until late May. Avoid planting trees in hot, dry weather.” – Anna Kinkley, OSU Extension Master Gardener

Sunscald damage on a dogwood tree.OSU Extension Service

Q: I have three ‘Venus’ dogwoods and today my landscaper came over to do some work and noticed the trunk of one of my trees was cracking on the surface and he thought it might be temperature related. He removed a couple pieces of the bark and it looked to him like it was healing. The area underneath wasn’t cracked, it was smooth. I was concerned about anthracnose. – Washington County

A: Your tree trunk was damaged by sunburn/ sunscald a year or more ago. It most likely occurred during the first year it was in the ground.

The damage doesn’t need any treatment other than to make certain you water the tree to at least 8 inches deep every week or two, especially during our dry months.

Then, too, a coarse mulch of bark chips at the base of the tree, extended outward to the dripline, will help conserve soil moisture. Keep it several inches away from the base of the tree.

You would be wise to remove the stakes on these young trees unless they’re unable to stand on their own. If they still require stakes, that indicates that their roots aren’t yet well established in the soil, most likely due to insufficient water.

Dogwoods are normally understory trees, where they are protected by larger plants/trees around them. In this sparsely populated planting, your dogwoods may require more supplemental watering than you had planned for. – Jean R. Natter, OSU Extension Master Gardener Diagnostician

BeansOSU Extension Service

Q: I’m having problems with bean plants. The edges of the leaves are withered and dying, and the plants themselves are stunted. It’s worse with pole beans in a large container. ‘Contender’ bush beans nearby are somewhat affected (I’m controlling by pulling the most symptomatic leaves, don’t know if this is effective), ‘Royal Burgundy’ bush bean in the same bed looks pretty healthy. Nasturtiums in the same bed show similar symptoms. Pole beans of the same type 30 feet away are doing just fine. Is this a virus, or is there a cultural problem I can fix? Do I need to pull the affected plants, and can I ever grow beans in that soil again? – Deschutes County

A: These beans look like they are getting too hot and too intense an amount of light. Is there a way you can reduce these a bit or move the container? Is there extra reflected light coming off some shiny material behind the beans? How is the air flow and ventilation in what appears to be an enclosed space where they are growing? Otherwise they look fine and I hope you get nice beans off them. – Toni Stephan, OSU Extension small farms expert

CarrotsOSU Extension Service

Q: Most of my carrots were delicious and well formed, however a few were disfigured. Can you suggest who might have caused this damage. – Multnomah County

A: Carrot storage roots are prone to splitting, with larger-rooted cultivars more affected than small ones, as they can take up more water. An erratic supply of water, such as heavy irrigation after a dry soil period, is the main cause of roots splitting in carrot. Under these conditions, the roots abruptly take up a great deal of water and undergo a surge in growth that their structure cannot cope with. Excessive nitrogen and fluctuating temperatures can also favor splitting of carrot storage roots. Luckily, only a few carrots suffered splitting in your planting, and it doesn’t appear that any secondary disease problems occurred. Sometimes these split-open roots are attacked by soft rot bacteria. – Cynthia Ocamb, OSU

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