What Are Ornamental Plants?
Ornamental plants include indoor and outdoor flowering and foliage plants, annuals and perennials, trees and shrubs, and turf. You'll find ornamentals in greenhouses, landscapes, interiorscapes, homes, lawns, golf courses, athletic fields, parks, cemeteries, sod farms and nurseries.
Ornamental plants are grown for both aesthetic and functional value. Healthy turf is not only an attractive groundcover; it stands up to tough use in lawns and athletic fields. Indoor plants create a warm environment and freshen the air. Landscape trees and shrubs enhance property values and can provide wind breaks, sun shade and privacy. IPM programs should preserve both the beauty and function of ornamental plants with a minimum of pesticide use and risks.
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Steps to Take
Monitor. By "scouting" or carefully checking your plants or turf, you can detect problems early while they're still small. Weekly scouting is a good practice. Keep detailed records of what you find. Which of your plants are most prone to pest problems? These key plants need to be checked most carefully and frequently.
Identification. Know which pests and beneficials to look for. Of the dozens of insects you might find in a planting, only a few, if any, are capable of causing any damage to the plant. What are the most important or "key" insect, disease or weed pests for your location? When is the best time to look, and which is the most efficient method for monitoring those pests?
Treat only when needed. Intervene in the natural process only when the benefits outweigh the costs. In nearly all cases, a single pest is not justifiable cause to treat. How many pests are truly too many? Young, rapidly growing plants in the spring may not be able to withstand as many pests as in the summer or fall season, or as many as older, more established plants can support without ill effects.
Customers buying ornamentals will often find plants with minor pest damage acceptable. Homeowners, park-goers or golfers are unlikely to object to or even notice a few aphids on landscape plants. The "aesthetic action level," or time to treat, is reached when pest levels are high enough to reduce your customers' perceived value of the plant – not when your trained eye spots the first pest.
Choose the best option. Can you reduce time, trouble and pesticide use and risks by removing a pest-prone plant from your landscape? Is there an alternative plant that is resistant to the key pests in your area? Lace bugs on the azaleas will not feed on the lilacs, so spot treat the azaleas, not the whole landscape.
Treat at precisely the right time. Pests respond to the weather, not the calendar. Use degree days when possible to time treatments to the most susceptible stage of your pest.
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Key Ornamental Pests
Scale insects. Scale insects are covered with a soft or hard "shell" that protects them from predators and some spray materials. Timing treatments against the young "crawlers" after they have left the protection of the scale and before they have formed their own shell, can be an effective strategy.
Spider mites. Check mite-susceptible plants frequently, especially in hot weather. Spider mite problems are notorious for exploding in just a few days in hot, dry weather. Drought stress can pre-dispose the plant to more serious mite injury. Applying beneficial mites or thrips that feed on pest mites can be effective in some situations. If you use a soap or oil spray that works by "suffocating" or dehydrating mites, be sure to get thorough coverage, especially on the undersides of plant leaves.
Aphids, planthoppers and plant bugs. These sap-sucking insect pests are usually more serious early in the season, and can often be ignored on late season plants. Many naturally occurring beneficial insects feed on aphids, so check closely to be sure treatment is truly needed.
Gall insects. Stem, twig and leaf galls are not the pest; rather, they are the plant's reaction to the pest. A gall is a plant structure formed by abnormal plant tissue growth. This growth is the plant's reation to a parasitic attack by bacteria, fungi, nematodes, mites or ticks, or insects. The gall forms a "bubble" around the attackers in order to separate them from the rest of the plant. Stem and twig galls can result in the death of plant parts and are generally more serious than leaf galls, which will often be shed by the plant without additional problems. Once the gall appears, it's generally too late to treat. Get the problem identified properly, and be ready to prevent it the next time.
Wood-boring insects. Boring insects often specialize in attacking plants stressed by old age, poor soil, poor location, drought or depressed vigor. Maintain optimum plant health as your best defense. Don't let borers move from declining trees to newly planted trees; remove infested plants before establishing new plantings. Treating after finding bore holes can be too late to do any good. Be better prepared next time.
Defoliators. Leaf-feeding caterpillars, Japanese beetles, lace bugs and others may consume entire leaves or "skeletonize" leaves, removing leaf tissue between the leaf veins. Healthy plants can often withstand a good deal of defoliation, especially late in the season.
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Greenhouse and Interiorscape IPM
Enclosed environments present unique opportunities for IPM and pesticide use and risk reduction. Many pests can be excluded from the growing environment by screening windows and vents. Environmental conditions such as temperature, relative humidity and soil moisture can be tightly controlled to keep them at ideal levels for pest suppression. Sterilize soil or potting media to reduce rot or nematode problems. Newly incoming plant material can be segregated, limiting contact with other plants until perfect health is verified. Beneficial insects that might disperse before completing their work in outdoor environments can be held captive in greenhouses and interiorscapes.
Consider removing and destroying pest-infected plants rather than nursing them along with costly pesticide applications. Thoroughly sanitize facilities after moving one crop out – before starting or moving new plants in.
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Successful Monitoring Programs
Unfortunately, despite the best intentions at the beginning of the season, monitoring programs often fall victim to the time crunch, dropping off the bottom of the priority list. Yet effective monitoring programs for your ornamental plants can and do save thousands of dollars in pesticide costs and improved customer satisfaction. Here are some tips to help you out:
Employees. Who will be doing the monitoring, if not you? A designated employee should be trained and enrolled in a continuing education program.
Schedule. Monitoring must be a priority, with sufficient time allotted to do the job thoroughly and correctly every week, not just as time allows.
Plan. Effective monitoring follows a regular routine, checking a specified number of plants, with particular attention paid to problem plants and plant parts. A haphazard, cursory check will not turn up problems until they're much more difficult to solve.
Tools. A knife, hand lens, sticky insect traps, collecting vials or bags, pest guides with color identification photos, a relative humidity meter, soil thermometer and moisture probes, a pH meter, notepad and pen are tools of the trade.
Communication. Your designated scout needs to have a way to relay results to those who need to know. Does your plant buyer know that one of your suppliers has been delivering infested plants? Does the irrigator know that excess water collecting in one corner of the nursery is promoting root rot? Add a written report, along with a circulation list, to the monitoring routine.
Evaluation. How well is the program working? Are customer complaints increasing or decreasing? How much does your scouting program cost? How much is it reducing your overall spray bill, customer callbacks or returns? What can be done to improve efficiency or results?
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