Ask an expert: There may be help for this maple with possible root rot – OregonLive

Gardening season has been put to bed for winter, but you may still have questions. For answers, turn to Ask an Expert, an online question-and-answer tool from Oregon State Universitys 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, type it in, and include the county where you live. Here are some questions asked by other gardeners. Whats yours?

Q: We have a previously very healthy hybrid maple (Acer saccharinum x rubrum) that appears to have developed a black weep and crack on the trunk.

We planted it in 2009 as a balled-and-burlaped nursery stock tree, and it has thrived until a year ago. (The trunk went from 2-inch diameter to about 15-inch diameter in 12 years.)

The weep developed after we had a professional pruning a little over a year ago. From what I can find on the internet (photos), it appears to be phytophthora fungal infection.

Is it possible to restore the trees health, or will the rot result in a potentially structurally unsafe tree over time? What should we look for in an arborist? I know you probably cannot point us to specific companies, but if you can give us a tip, thatd be really helpful. Multnomah County

A: Argh, that doesnt look good. But it may not be the end of the tree. Phytophthora is probably a pretty good guess, but there are several other possibilities. Here is a link to the PNW Plant Disease Management Handbook re: maple and phytophthora diseases.

This includes both cultural and chemical solutions, although chemical methods are generally protectants, there are phosphonate fungicides that appear to slow the phyphthora down.

First you may want to look at the drainage situation around the tree. Does it appear compacted and perhaps there is standing water a lot of the time? This can facilitate phytophthora. Is there any way to improve the drainage issue if you think it may be a problem?

Regarding arborists, you may want to try a consulting arborist one that can do diagnosis and recommend treatments, but wont be the one to do the treatments, so they are not likely to recommend things that arent absolutely needed.

Here is the PNW ISA (International Society of Arboriculture) website with a find an arborist page, with a directory.

In the directory, the arborists will note whether they are consulting arborists or not. Dave Shaw, OSU Extension forestry specialist

Apple treeOSU Extension Service

Q: I just noticed this as I started pruning my Liberty apple tree. What is it and how should I deal with it? The entire branch is nonproductive perhaps I should cut it back to the trunk?

A: This is likely apple anthracnose canker. Infection generally occurs during fall rains and first appears as a small, circular red spot on the bark; new cankers are most visible when the bark is moist. The discoloration extends into the tissue as far as the sapwood, which contains the functioning vascular tissue.

Disease management relies heavily on pruning out the cankers to remove the inoculum source. Stems or trees that are heavily infected with cankers should be removed from the orchard and burned. The mainstay of apple canker control is pruning out the cankers. If the canker pathogen is a fungus, prune off the cankers in early summer. After that, spray the area with a Bordeaux mixture or approved fixed copper materials. Since fungal cankers only attack apple trees suffering from drought or other cultural stress, you may be able to prevent these cankers by taking excellent care of the trees. Chris Rusch, OSU Extension Master Gardener

How is this conifer doing?OSU Extension Service

Q: Im not sure what the correct name is of this conifer. It looks nice on the outside, but underneath there is a lot of dry leaves. Last year it was the same. Is that normal? Should I do anything? Multnomah County

A: Actually, the conifer is in excellent condition. And thats in spite of the direct heat from it receives from both the west and the south; the limited rooting area; and the heat reflected from paving on two sides! The dense growth is simply shading out some of the interior growth, a normal occurrence. Such shade is not a problem and that sort of dead growth may be removed whenever it is seen, The only thing you need to do is to remove each brown branch at its source, but dont cut the brown off in such a way that leafless stubs remain. With conifers, bare branches dont re-sprout. Jean Natter, OSU Extension Master Gardener diagnostician

There are many azalea hybrids. This one is fragrant.OSU Extension Service

Q: Can you please tell me what type of plant this extremely fragrant, yellow-flowering bush is called? Linn County

A: This is an azalea (Rhododendron species). There are many azalea hybrids, so what species it is exactly is unclear. However, Rhododendron luteum would be a good guess as it is both yellow and perfumed. James Mickley, OSU Extension Herbarium curator and instructor

Either seeds or seedlings can be planted in a straw bale garden. Oregonian file photo. Marv Bondarowicz/staff

Q: Can I set straw bales up in February for the rain to soak them then fertilize two weeks prior to planting in April? Lane County

A: That will usually work. Often in the first year the first planting is done in a trench in the bale with fertilizer. Adding fertilizer now will also help prepare the bed. The straw breakdown creates some heat from composting once temps reach into the mid-50-60s. Pat Patterson, OSU Extension horticulturist, retired

ClematisOSU Extension Service

Q: The photo Ive attached show a clematis vine on an L-shaped trellis (I dont recall the plant variety). I have another, too. They were planted about two years ago and never bloomed very well (probably due to my lack of care!)

They began blooming this year in early to mid-April. The best blooming plant faces south (but my house is about 25 feet away) and only has growth at the base and at the top (no growth in the middle). The other struggling plant faces west, but is shaded in the afternoon by another wing of my house, but it has absolutely no growth from the base to the top, and is only flowering at the top.

The plants get about six hours of sun. I dont know if I should prune it, and if so how much and when? What would cause the bare portions of the stems? I have not fertilized it. Washington County

A: Some clematis literally jump out of the ground the spring after they are planted whereas others slog along, takingseveral years to gear up. Those available with their rootball wrapped in plastic are often sluggish. Except for the bare stems, yours currently look fine.

I doubt theres anything to be concerned about as long as the bare portions didnt have leaf spots or other problems. Clematis growing in clay-based soil seldom need additional fertilizer, but may do well with a boost after they are pruned.

Clematis thrive with annual pruning, with the timing varying according to the group the clematis belongs to. In general, a useful guideline is after bloom. A practice that works well with large-flowered spring-bloomers such as yours is to cut back the stems to about 12 inches, then wait for the abundant new growth that will support next years flowers.

You can fertilize after pruning to help the clematis put on new growth. If it has a second bloom later in the year, dont prune again. A second bloom is likely to be less showy than the first. Youll find lots of clematis info, with the bulk of the basics on the first several pages, here: A Clematis for Every Garden

-- Jean Natter, OSU Extension Master Gardener diagnostician

Shiny geranium (Oregon State University)LC-

Q: My yard is mostly shady. It was invaded by shiny geranium (Geranium lucidum) about two years ago. We can keep it out of the raised flower beds pretty well but the lawn is awful. Weve tried heat killing it with black plastic (reused) tarps. It works, but they just re-invade. We dont want to use Roundup. We are not physically capable of hoeing them myself anymore and the yard guy is understandably reluctant to keep fighting such a tedious battle. What other options are there? Clackamas County

A: Shiny Geranium is an aggressive and tenacious invasive weed. It sets so many seeds that areas with the plants develop a heavy seed bank in the soil. There are details offered in some resources Ill share, yet the basics are control it twice a year, cover the seeds with deep mulch to inhibit germination and establish plants to cover or inhibit the geraniums growth.

In the lawn your strategy could include regular mowing to reduce seeding and keeping the turf very healthy. This means appropriate fertilization, mowing, watering and rejuvenation when the grass thins.

Healthy lawns require sunshine, though. Is there a way to get more sun to the area? Alternatively, other plantings might be a solution. Or regular organic mulch application?

Heres a prior answer about shiny geranium options.This Oregonian article has Extension Service information. And,thisposting from King County in Washington is fairly detailed. Learninghow and wherethe plant grows is useful when needing to disrupt it. Jacki Dougan, OS Extension Master Gardener

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Ask an expert: There may be help for this maple with possible root rot - OregonLive