Researching Maintenance

Shear agony We maintain a large apartment complex. Recently, the managers told us to stop shearing the shrubs because this was unhealthy for the plants. However, shearing seems like the only economical way to keep the shrubs under control. Who's right?-California

Shearing simply is bad pruning for many plants. Exceptions exist, of course. Boxwoods, yews, privets and many other plants accept shearing well, which is why such species are the usual choices for hedges. The problem is that some operators shear everything. The list of frequently abused species is a long one, but consider these common examples:

* Azaleas. Obviously, the primary value of azaleas is their bloom. Shearing destroys the bloom, and it's usually not necessary because most azaleas are well-contained with little or no pruning.

* Forsythia. Forsythia is a fast-growing shrub that definitely requires attention. However, shearing eliminates the dramatic "wands" of flowers and turns the branching structure into a chaotic mess. A better method is selectively cutting the oldest stems down to ground level. Some horticulturists even cut all the stems to the ground annually.

* Heavenly bamboo, Nandina domestica, is popular mainly for its foliage and form, which shearing will destroy. As with forsythia, it's best to reduce its size by selectively cutting the oldest and largest stems at ground level.

Ironically, shearing sometimes results in more work because it creates debris that must be raked. By contrast, selectively cutting stems or branches often results in a small stack of brush that can be carried away under one arm-no raking.

Additionally, most plants maintained with a more natural form-unlike sheared plants-do not rapidly develop an unkempt appearance as a result of new growth. Consequently, a shrub that might require a light selective pruning once a year may need shearing two or three times annually.

Operators who think they're saving time and money by shaping everything in the landscape with power shears should stop to consider that, in many cases, they could save time and create healthier, more attractive plants with a little restraint.

From the land down under Do you have any information on the Austree tree?-Oregon

The Austree is a hybrid of two willows: Salix matsudana and S. alba. It was developed and released by the New Zealand government. "Austree" actually is the name of the licensing arm of the New Zealand government, and other Austree varieties are available. However, the Salix hybrid is the best known.

U.S. distribution rights belong to Rocky Mountain Austree Inc. (Colorado Springs, Colo.), which sells direct via its website ( as well as through certain nurseries with which it has distribution agreements.

According to Dennis Warnecke, president of RMA, people use Austrees primarily in landscapes, windbreaks and screens. Its extraordinary growth rate of 8 to 15 feet per year makes it well-suited for creating shade and windbreaks in a hurry.

The Austree appears to have several advantages over other fast-growing trees. It is hardy in Zones 3 through 10 and, according to Warnecke, does not spread by suckers or seed. Further, it seems to be relatively long-lived and free of pests. Some arborists, still mindful of past "super trees" such as the now-infamous Lombardy poplar, have taken a wait-and-see attitude with Austrees. However, they've been grown successfully long enough in the United States now to be gaining some acceptance.

The Austree is not generally picky about conditions, though it does require ample water to thrive, especially during its first few years. Thus, explains Warnecke, it isn't a tree for no-maintenance sites where it will receive no care at all.

Surviving the floods How did plants fare during the North Carolina floods?-Massachusetts

Dr. Stuart Warren, a horticulturist with North Carolina State University, says that, in general, flood-related injury to ornamentals was not as severe as originally feared. Most of the common shade trees-red maples, sycamores, willow oaks and birches-naturally grow in moist or wet sites, so they tolerated 1999's flooding well. On the other hand, azaleas seemed to be especially susceptible, and many were lost.

Many Carolinians are still simply trying to put their lives back in order, so not a lot attention has yet been paid to how landscape plants fared. Thus, Warren explains, we may not yet comprehend the full consequences of the flooding. The silt and debris deposited during the waters buried the trunks and stems of many plants, creating the same effect as planting too deeply. Resulting problems may manifest themselves over the next several years.

Japanese beetles-hard to resist What are some Japanese-beetle-resistant plants?-Ohio

The Japanese beetle is here to stay. It makes sense, therefore, to use resistant plant varieties and avoid those that are particularly susceptible if you're in an area where this pest is prevalent. The U.S. Department of Agriculture's Animal and Plant Health Inspection Service (APHIS) has published a list of resistant and susceptible plants. The table below is drawn from the APHIS list.

On May 16, the Canadian House of Commons Environment Committee issued its report, Pesticides, Making the right choice, For the protection of the health and the environment. Written from an overtly anti-pesticide perspective, it contains many of the same buzzwords found in the Food Quality Protection Act (FQPA), which Congress enacted in 1996. Endocrine disruption, cumulative and aggregate risks, and "sensitivity of children" all receive particular attention in the report.

The committee's suggestions include:

* "To homeowners and residents of urban and rural areas, we say dandelions are harmless and beautiful. They do not pose a threat to health; herbicides do, particularly to children. Therefore, it is desirable to accept dandelions as a natural presence in the Canadian landscape."

* "Accept diversity as an integral part of a healthy environment. A lawn is not an artificial carpet. It is a living area which contains a host of inoffensive and even highly useful organisms (plants, insects and earthworms)."

* "The Committee urges the develop a strategy for the gradual phase-out of pesticides used for cosmetic purposes."

In place of synthetic pesticides for landscapes, the committee suggests, among other remedies, domestic ducks for controlling garden weeds and "natural teas" made from rhubarb, onion, garlic and soap to repel insect pests.

The report's release follows the late-1999 introduction in the Canadian Parliament's House of Commons of Bill C-388, "An act to prohibit the use of chemical pesticides for non-essential purposes."

Marlene Jennings, the House member who introduced C-388 explained, "This bill seeks to impose a moratorium on the use of chemical pesticides for esthetic purposes on home lawns and gardens and on recreational facilities such as parks and golf courses."

As of this writing, C-388's fate is not certain. However, many members of the Liberal Party, which holds substantial majorities in both houses of the Canadian parliament, support this legislation, so its chance for passage seems good.

Corn gluten meal, developed by Dr. Nick Christians at Iowa State University, is the only commercially available "natural organic" pre-emergence herbicide. Though relatively expensive, and not as effective as traditional herbicides, corn gluten's unique status has garnered significant attention.

Corn is not the only grain from which gluten-a combination of two proteins-can be derived, however. Wheat also is a significant source. Researchers from Montana State University recently conducted a study to better define wheat gluten's herbicidal properties.

The researchers, Dr. Robert Gough and Ron Carlstrom, tested wheat gluten meal on 17 weed species. Depending on the rateused, germination was reduced by 50 percent or more in 12 of the 17 species. Particularly sensitive species included leafy spurge, pigweed, shepherd's purse, henbit, quackgrass, annual bluegrass, Canada thistle and orchardgrass.

If this laboratory performance translates to field tests, wheat gluten will hold great promise as a practical weed control. In these experiments, wheat gluten meal provided control similar to corn gluten meal at just one-third the rate. This is significant because the high rates (compared to synthetic herbicides) required for corn gluten meal are responsible for its relatively high cost. And this cost is difficult to reduce because the price of gluten, which is derived from grain, is controlled by commodity markets. If wheat gluten is effective at lower rates, it could result in a significant new choice for turf managers interested natural organic controls.

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