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IN THE GARDEN: Hibiscus can fall prey to several insect species, but treatment is possible

by Janet B. Carson December 31, 2022 at 1:31 a.m.
Sap sucking insects like whiteflies often attack hibiscus plants indoors, where neem oil, insecticidal soap or showering are all treatment options. (Special to the Democrat-Gazette)

Q: Here are the yucky pictures. I have had to cut all of the hibiscus plants back. That is a new bud, but it looks infected/infested, so I cut it off too. I have treated all four plants with neem oil. Please tell me what do.

A: Hibiscus plants can be plagued by several insects — whitefly, aphids and mealybugs — all of which suck sap out of the foliage and can give off a sticky honeydew. The red and black spotted insect looks like an Asian ladybug which will eat the aphids. The holes in some of the leaves could have been caused by a beetle or caterpillar, but that isn't anything to worry about now. The neem oil should have done the trick, but if you continue to see new insects, try using an insecticidal soap indoors. You can also remove their water collecting trays and move them into your bathtub, and shower them first. Often these insects multiply more rapidly when it is dry, and the shower (with tepid water) can remove them. Then follow up with a spray of insecticidal soap.

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Q: Our son was helping us to complete some yard work. He came across this invasive tree on our walnut tree. Our question is should we cut this invasive tree off and how? Thanks so much for your assistance. Have a great New Year.

A: It could be a root sucker or a seedling tree that grew too close. Regardless, you need to remove it. You can use loppers or a heavy-duty pruner to remove the top growth, and then try to cut the base of the sprout as close to the ground as you can with a pruning saw, trying not to cut into or damage the walnut tree trunk. Just cutting it will not kill it. It will sprout back out, but if you keep cutting it, eventually you will wear it out and it should stop. Good luck, and Happy New Year to you as well.


Q: I know you are probably bombarded with readers asking about their plants and what to do with winter damage. I have babied gardenias for years, and I did try to cover them (I live slightly north of Conway) but the blankets were in my neighbor's yard the next morning. What do you think the chances of them having survived this cold snap are? Is there anything I can do to improve their chances?

A: Many gardeners are worried for their plants, but for now, all you can do is pray for a good outcome. At this point the jury is still out, plus we have at least two more months of winter. Once they thaw out, you could see some burned leaves, but for now, ignore them. Any damaged leaves can serve as protection for the remainder of the season. Let's not do any pruning until we know for certain what to prune — and that won't happen until spring.

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Q: I have a two-car garage where I store one car and use the other half to overwinter my plants. They have always done well with this scenario, but perhaps it got colder than normal, because some of them look dead now. Should I just toss them, or is there a Hail Mary that will give them a fighting chance?

A: Tropical plants typically thrive in warm, humid environments but can survive as long as temperatures do not fall below freezing. Depending on your garage, and the insulation, number of windows, etc., temperatures might have fallen below freezing during our most recent cold snap. Clustering the pots as close together as you can, as close to the house as you can, making sure the soil is not bone dry and adding a little extra protection around the pots can help in the future. Even if the top growth is damaged, it is possible the base of the plants and the roots are alive. You have already moved them in, so why not wait and see what happens next spring? Then cut them back and see what grows.

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DEAR READERS: A reader has some bonsai wire she no longer needs. If you have need of it and live in Central Arkansas, let me know.

Retired after 38 years with the University of Arkansas Cooperative Extension Service, Janet Carson ranks among Arkansas' best known horticulture experts. Her blog is at arkansasonline.com/planitjanet. Write to her at P.O. Box 2221, Little Rock, AR 72203 or email jcarson@arkansasonline.com


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