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LifestyleColumnistsJessica Damiano

Why tree topping is bad, what you should do; getting rid of whiteflies

Whiteflies on an African Violet.

Whiteflies on an African Violet. Photo Credit: Sandra Wechsler

DEAR JESSICA: Can I transform a Styrax japonicus from a tree to a bush? It was planted too close to an aged oak tree about seven years ago and is now about 20 feet tall. The initial trunk has grown to about 3 inches in diameter. Three additional trunks have arisen from the base of the trunk and are now about 8 feet tall. Transplanting is not a consideration, and I question whether or not it can be cut back and trained to be a bush. If so, can the main trunk be cut at the base, leaving the three remaining smaller trunks? Should this be done in stages, and what height should be established? And could you please address fertilization during the transition?

— Albert Marino,

Port Jefferson

DEAR ALBERT: It’s not uncommon to train a shrub into tree form by removing lower branches, but the opposite is problematic. You really can’t cut the terminal leader (main trunk) off a mature tree without seriously compromising it and creating external hazards.

Removing or shortening the main trunk — also called “topping” — would stress your Styrax japonicus (Japanese snowbell) for several reasons: Much of the tree’s food-producing foliage would be lost, the large wound left behind would leave the tree susceptible to insect and disease damage, and — because the tree’s response would be to produce many side shoots that would compete for dominance — the sudden loss of energy would further weaken its structure.

In addition, cutting the main trunk midway could cause the tree to become unstable and hazardous, as side shoots would grow to the point where they’d make the tree top heavy, putting it at risk of toppling and potentially causing injury to people and damage to property. Because of that, you’d also be setting yourself up for routine maintenance to keep that growth in check. What’s more, the center portion of your tree would look like those street trees that utility workers decapitate to keep from growing into power lines. Not a good proposition no matter how you look at it.

However, if your only alternative is eliminating the tree altogether, and the tree is not in an area where injury to people or damage to property could occur in the event it topples, then you may not have anything to lose. Topping is never a good option, but I have a backup plan that would minimize the risks and damage: Cut the leader back to a lateral branch instead of lopping it off at the base or mid-trunk.

This means seeking out a branch that’s growing horizontally from the leader and cutting the leader on the diagonal just above where the two meet, following the angle of the lateral branch crotch. For aesthetic purposes, select a lateral branch that’s taller than the three smaller trunks.

Keep in mind that removing more than 20 or 25 percent of a tree’s canopy under any circumstance will put the tree’s health at serious risk. The best time to prune is in late winter or early spring, when the tree is dormant, but July is second-best, so you can safely do so now. Afterward, apply a 5-10-10 fertilizer to aid recovery.

DEAR JESSICA: I have had African violets for many years. I just found white flecks on some plants. What are they and how do I get rid of them?

— Sandra Wechsler,

North Bellmore

DEAR SANDRA: Looks like you’re dealing with a whitefly infestation, and you can manage it by bathing your plant.

First, take the plant outdoors and shake it. This will cause some of the insects to fly off the plant. Obviously, don’t do this near your outdoor plants.

Next, take the plant back indoors and carefully dip it upside down in a gallon of room-temperature water to which you’ve added a tablespoon of ordinary dish soap (not automatic dishwasher detergent or any soap that contains bleach or antibacterial ingredients). Take care not to spill soil. Repeat this every five days until you no longer see evidence of the pests.

Alternatively, you can spray the plant with insecticidal soap, following package directions and ensuring complete coverage, including the undersides of leaves.

Be sure to isolate the affected plant from other houseplants until control is achieved to avoid spreading the infestation.

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