Q: I have dandelions that are well-established throughout my lawn, some with 2-inch diameter taproots, some a lot smaller. I also have a colony of bees that lives in the ground in my yard and comes out every spring. Because of the bees, I’ve avoided “weed and feed” or anything like that. An English walnut tree dumps leaves on the yard, affecting the quality of the soil.
What would you recommend to begin to remove the dandelions and augment the soil to prevent them from coming back? What would be important to do to protect the bees? The rest of the lawn is a mix of daisies, buttercups, clover, grass and another flower I don’t know the name of. I probably can’t dig out the dandelions as there are so many of them.
A: There are no products that effectively control dandelions that can be broadcast over an area without harming the other plants and possibly the ground-nesting bees. Some people have decided to simply live with dandelions rather than endanger bees and other plants with a broadcast application of chemicals.
Aside from digging them out, your best approach may be to use glyphosate (such as Roundup) as a targeted spray applied to individual plants. These products can be purchased in small spray bottles for this type of application. However, it is important to read and follow all instructions and precautions on the product label.
This information is from Oregon State University’s Pacific Northwest Weed Management Handbook: “Glyphosate … moves more efficiently from leaves to perennial roots if it is applied to actively growing foliage, usually in midseason just before bloom; consult label for details on specific weeds. Glyphosate is strongly adsorbed into soil and has no activity once it contacts soil.”
Dandelions are opportunists, as are most plants we consider weeds. They grow in almost any conditions and there are no soil conditioners or amendments that will prevent them. The most effective way to prevent large numbers from taking root is by keeping the soil covered with mulch, dense plantings or a thick, healthy lawn.
— Bill Hutmacher, OSU Extension master gardener
Trimming back pussy willows
Q: How can we trim our pussy willow branches so they don’t grow so high they are up to the roof? In the past we have just cut them straight across. There must be a better way. We are sick of pruning them every year but we don’t want to lose the plants.
A: Willows are vigorous growers that respond to pruning by making many more fast-growing branches. If you cut the willow back severely to about a foot above the ground, it could grow back to its original size in 1-2 years.
When this plant is close to a house, pruning yearly may be the only option outside of moving it to a place where it can ramble. This is just one of those fast-growing trees/shrubs that won’t quit.
— Nicole Sanchez, OSU Extension horticulturist
A jasmine with red spots
Q: My jasmine has some kind of blight that seems to be killing it. It dropped lots of leaves during the summer and looked like it was dying from the inside out. The remaining leaves are dark red. Whatever the problem is, it’s spreading. Newly infected areas have distinct red spots on the tops and undersides of the leaves. Is this rust or something worse? Is there a way to save the plant?
A: Star jasmine is marginally hardy in the Pacific Northwest. The red spots and blotches are a response to low temperatures. A more severe indication of excessively low temperatures would be dropped leaves.
If low temperatures threaten again this winter, consider temporary protection during the coldest hours. You can use a commercially packaged frost blanket, which is a non-woven fabric you can obtain at a garden center. Or, in an emergency, throw a bed sheet over the trellised plant. Be certain to remove the protection during daylight hours when temperatures rise.
— Jean Natter, OSU Extension master gardener diagnostician
Houseplant may need more water
Q: How do I know if my money tree is drooping from lack of water or too much water?
A: The correct water needs for houseplants are a challenge to determine, and it’s unlikely I’ll be able to diagnose the issue for you without seeing the plant.
However, I do have suggestions to help you care for your plant. There are multiple plants commonly called “money tree.” If yours is Pachira aquatica then it is a plant from rainforest areas that flood regularly. The Missouri Botanical Garden says, “If grown away from water bodies, plants need consistent moisture. Houseplants perform best in bright light with moderate but even moisture.”
Let the potting mix dry on the surface between waterings, and check that your pot’s drainage is good. Soggy soil or standing water can cause the plant to die from root rot.
— Jacki Dougan, OSU Extension master gardener
How to prune a Japanese maple
Q: I have a 5.5-foot-tall Japanese maple that has never been shaped or trimmed. Is this a job for a professional or is this something a homeowner could attempt? It has one large dead branch on the main trunk that needs to be cut off. What precautions should I take? If you believe I need a pro, what qualifications should this person have?
A: As a gardener who has killed a Japanese maple, I recommend that you consult a professional to take out the dead branch and see what they suggest for care. Your tree seems very close to pavement, which may cause issues if we get another very hot summer like last year, and a professional may have some suggestions for heat mitigation. They may also be able to tell you about the cause of the dead branch.
Search on the internet for Tree Service or Arborists Near Me, and be sure to choose an ISA-certified arborist, preferably one who has knowledge of Japanese maples. Try to get three estimates/opinions, and check that they are licensed and bonded. You can also ask neighbors about tree work they have had done.
If you decide to try it yourself, it’s key to:
• Take out as little as possible — less than 1/5 of the tree.
• Keep your pruners sharp and sterilized.
• Remember that all cuts wound the plant, so don’t prune when leaves are emerging or dropping as these are low-energy times for the plant.
— Rhonda Frick-Wright, OSU Extension Master Gardener
Got moss? No problem
Q: We recently found a bald spot on our Japanese maple. We believe this showed up after some recent high winds in the area. Our questions are: Should we be concerned? If so, how can we best treat this? There is quite a bit of moss on the tree. Is that of concern as well? Should we attempt to remove it?
A: The white on the trunk looks like lichen. Both moss and lichen don’t harm trees and you don’t need to take action.
— Weston Miller, OSU Extension horticulturist
Salmonella may still be harming birds
Q: In the past week, my wife and I have found five dead golden finches in our yard. We do not have a cat nor do our neighbors, and there was no sign of harm or foul play. It’s been cold, obviously. Any word of this happening elsewhere, or any advice on what we can do to keep these little guys alive?
A: I cannot say for certain, but I suspect from my own observations and those of others locally that last year’s salmonella outbreak is continuing. In the past, there would be outbreaks, everyone would take down their feeders for a while and the outbreak would abate. Now it seems like it’s just a continuous issue.
Salmonella gets passed via contact with waste/excrement on the feeders, with many little feet picking it up, carrying it elsewhere and “sharing it” in feeding flocks and depositing it on other feeders and surfaces.
Just because the birds are dying or being found in your yard doesn’t mean that the birds are (only) picking up salmonella on your feeders. Winter songbirds are likely traveling the neighborhood and sharing many people’s feeders. This provides a very strong reason for each of us to clean our own feeders frequently — between fills and at least monthly is a good practice — and to encourage our neighbors to do likewise.
The CDC has some good tips for easy disinfection of feeders, as well as tips to keep ourselves healthy when disposing of the birds at bit.ly/3qsfPmr.
— Dana Sanchez, OSU Extension wildlife specialist
Ask an Expert is an online question-and-answer tool from Oregon State University’s Extension Service. To ask a question, visit extension.oregonstate.edu/ask-expert.