Q: Can you tell why this plant is dying? — Barb L.

A: Thanks for sending the photos of your Schefflera houseplant. Diagnosing plant problems often requires detective work, and there are often multiple factors that cause similar symptoms. When there aren’t concrete, visible causes, such as insects present, we can consider various possibilities, eliminate those that obviously don’t pertain and then act on those that might. A combination of causes can also be responsible for plant decline.

Your Schefflera has lost many leaves and several existing leaves are showing browning in the center. Possible causes include summer sunburn or improper water quality, such as water that’s been mechanically softened. Such water often leads to salt or mineral buildup in the soil. Lack of fertility is rarely a cause for houseplant decline, so fertilizing an ailing plant isn’t recommended until its health improves.

What’s the best remedy for this plant? Sometimes we need to let go of a suffering houseplant, and start over with a fresh plant. If a plant has sentimental value, or you’re up for a challenge, here’s what to do: Cut the plant back to about 3 to 6 inches above soil level, even if only bare stems remain, and repot into totally fresh, high-quality potting mix. Place in direct light close to a window. A little sunshine is good during winter, but summer’s intense sunlight should be filtered.

A drastic cutback and repotting can often stimulate a plant into production of fresh new growth. Sprouts should begin to be visible within about two weeks. If you try this, please keep us posted.

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Q: I have a 4-year-old Prairie Magic apple tree and this year I had the start of a great crop until hornets began eating into the apples, causing spoilage. Do you have any suggestions for preventing this next year? — Jeff W.

A: In late summer and fall, wasps and hornets change their feeding preference from proteins to sugars, making ripening fruit extremely attractive. Besides damaging fruit, these aggressive insects also make picking dangerous.

Unfortunately, there don’t seem to be sprays, repellents or other products that can be recommended or applied that would effectively control these insects, while being safe to use on ripening fruit. Finding the nest is often difficult.

Suggestions include the following: Remove all fruit damaged by birds or other causes quickly, as these insects are quickly attracted to them. Harvest fruit promptly when ripe, and remove fallen apples.

Wasp and hornet traps are available, which can be located slightly away from the fruit tree. Place the traps before fruit begins to ripen, because once the wasps and hornets have found ripe fruit, the traps will be of little benefit.

One novel suggestion that’s worth a try is to locate a container filled with muskmelon or watermelon rinds, or similar fruit refuse, a slight distance from the tree. Do this before the apple tree ripens, and wasps will swarm to the currently available sweet food source, possibly lessening the attraction of the apples.

Q: I moved my Thanksgiving cactus to our dining room table so we could enjoy the blossoms, since it’s blooming so nicely this year. But now all the flowers are all falling off and it looks terrible. What did I do wrong? — Jane W.

A: I’m a good person to speak about plant mistakes, because I’ve made most of them myself. One such mistake is moving Thanksgiving and Christmas cactuses while they are in bloom.

These holiday cactuses flower in their existing location through an interaction of cool nighttime temperatures and shorter daylight hours. When their needs are met in that specific location, they reward us with flower buds and blossoms, showing they’ve become well-adapted to that site.

Unfortunately, when these plants are moved away from the location in which they’ve grown comfortable, the change often results in dropped flower blossoms. The slight difference in temperature, air movement, light level or humidity might be responsible.

Holiday cactuses are much more temperamental about moving than most indoor plants. If you’d like to try moving a beautiful flowering holiday cactus to a more visible location temporarily, hold your breath and cross your fingers. Sometimes it works, often it doesn’t.

If you have a gardening or lawn care question, email Don Kinzler, NDSU Extension-Cass County, at donald.kinzler@ndsu.edu. Questions with broad appeal may be published, so please include your name, city and state for appropriate advice.