Landscape & Irrigation

May/June 2017

Landscape and Irrigation is read by decision makers throughout the landscape and irrigation markets — including contractors, landscape architects, professional grounds managers, and irrigation and water mgmt companies and reaches the entire spetrum.

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32 May/June 2017 Landscape and Irrigation www.landscapeirrigation.com LANDSCAPE AND TURF MAINTENANCE The Science of Shrub Care ■ BY BRANDON M. GALLAGHER WATSON Shrubs are key to landscapes in just about every setting. With all their various shapes, sizes, textures and colors, shrubs dominate homeowner associations, commercial properties, corporate campuses, even residential areas — and are often vital to the structure of the landscape design. While trees have arborists who specialize in their health, and turf care professionals can address grass issues, the care of shrubs almost always falls to the landscape managers. If your clients are looking to you to not only keep the shrubs trimmed and manicured, but healthy and vibrant as well, there are some things for which to be on the lookout. Insects and diseases Insect or disease issues on shrubs run a wide gamut from very species-specific issues (such as boxwood blight) to more general pests (such as aphids). Rather than get into any particular management strategy, it is useful to use broader categories such as "potentially fatal issues" and "cosmetic issues." The first group is pretty straightforward; left unmanaged, this issue will likely lead to the death of the plant. This could be something such as the ficus whitefly (Singhiella simplex) or the aforementioned boxwood blight caused by the fungus Cylindrocladium buxicola. Left to their own devices, these pests will kill the host plant. Landscape managers are left with the choice of either treat for the issue or plan to have the plant removed and replaced. The second broad category of health concerns — the "cosmetic issues" — is a little less straightforward. Admittedly, I'm biased by my tree care background. In arboriculture, we are taught to educate the client on why aesthetic issues are "just unsightly — it won't kill the tree so don't worry too much about it." Occasionally we run across the client who doesn't want a leaf out of place, so we still offer some of these services, but it is not considered standard practice. Shrubs, however, are a little different than trees in this regard. We can talk a client into ignoring some leaf spots on their oak when the spots are 30 feet above their heads, but when the leaf spots are at eye level, as they are with shrubs, the client may not be as easily swayed. Untreated cosmetic issues on shrubs lead to an undesirable plant that is simply removed and replaced. Thus, aesthetic issues really do become potentially fatal issues for shrubs, and warrant management more often than not. Scouting for insect and disease issues should be a routine part of walking your clients' properties. Symptoms to keep an eye out for include underdeveloped tissues (such as stunted leaves, shorted internodes, and failures of flowers or fruits), overdeveloped tissues (such as galls, witches brooms, or unusually PGRs keep shrub growth in check.

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