Q: Can you identify the tree and berries in the attached photo? — Brooks W., Lakota, N.D.

A: When trees or shrubs no longer have leaves to assist identification, we depend on bud shape and arrangement, twig characteristics, fruit or seeds, bark type and any other clues we can glean.

From the photos, there are several clues. The dark black fruits are clustered in a certain arrangement. The diagnostic tool I find most helpful for this species is the "sub-opposite" bud arrangement visible on the twigs, in which one pointed bud is slightly below the other. This species also has white "lenticel" dots on younger twigs.

The plant is common buckthorn, whose botanical name is Rhamnus cathartica, and it grows as a large shrub or small tree. The fruits are inedible for humans, usually causing severe gastrointestinal upset. Birds, on the other hand, consume the fruits readily, spreading the seeds randomly in their droppings. As a result, common buckthorn pops up in unexpected places and can spread uncontrollably. For that reason, it’s classified as a nuisance or invasive species in many regions.

Unfortunately, the toxic fruits are sometimes mistaken for chokecherries. Last year a caller made jelly from the fruits before questioning their identity. When we identified the tree as buckthorn instead of chokecherry, she was able to dispose of the jelly before giving it as gifts, avoiding an unpleasant circumstance.

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Q: How can I control the small flies that are flitting around my houseplants? The small black flies are a nuisance, and I even feel them tickling my nose when I’m close to the plants. I’ve tried spraying, but they keep coming back. — Marge, Fargo.

A: The small black flies are probably fungus gnats. The adult flies lay eggs in the soil, which hatch into larvae that in turn become adults. Spraying the gnats with houseplant insecticide can temporarily kill the adults, but eggs in the soil soon produce new adults, and the life cycle continues. Although the adult gnats cause little harm, the soil-borne larvae can feed on houseplant roots, opening the way for rotting organisms.

To effectively control fungus gnats, the life cycle must be broken. This can be accomplished with a product called Mosquito Bits, which might sound funny, but the label also indicates that it controls fungus gnats. The product’s active ingredient is a special strain of the organic insecticide Bacillus thuringiensis, which kills the fungus gnats in their small, larval stage as they live in the potting soil.

The granules are spread on the soil following label directions. I’ve seen Mosquito Bits sold in garden centers, farm supply stores and national chains.

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Q: I’d like to plant several apple trees in our yard, and I’m considering Honeycrisp, Haralred and one developed in Canada called Ambrosia. What are your thoughts? — Carol, Fargo.

A: Honeycrisp and Haralred are great choices that have a good track record of growth in the Upper Midwest. Honeycrisp is an all-purpose apple that can be used in baked recipes but also has an appealing flavor and texture for fresh eating. It stores well through winter.

Haralred is essentially a form of the popular Haralson, but with a more uniform red color. Some feel Haralred is slightly less tart. Haralson and Haralred are great apples for pie and other baked goods because they hold their texture well. Both store well under refrigeration.

But the Ambrosia apple isn’t on the list of best-recommended apples for our region. Sometimes when we hear a variety is developed in Canada, we automatically think winter-hardy. But Canada is a wide country, and coastal regions can be quite mild.

Ambrosia apples originated from a chance seedling discovered in an orchard in the fruit growing regions of British Columbia, on Canada’s mild Pacific coast. Most sources I researched list Ambrosia as winter hardy in zone 5, whereas our apples must meet the hardiness criteria of zones 3 and 4.

Although Ambrosia sounds like a tasty apple from its descriptions, it likely would not survive our growing conditions. Instead, you might consider Zestar, Prairie Magic, State Fair or Sweet Sixteen as companions for your Honeycrisp and Haralred.

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.