Manage the Problem
Management techniques are implemented, from the least toxic on up, after determination is made that the condition is unacceptable. These techniques are cultural practices, mechanical and biological management. The fourth technique, chemical, will be covered in the next article. With each of the first three management practices, you will find a few examples of how to implement them in your garden. In practice, when faced with each problem, determine the least intrusive method of containing the problem with the goal in mind of maintaining a garden in harmony with nature.
A Practical Example
Let’s look at the decision to weed the garden as an example. Why do you have a weed? Did the weed seed blow in from a neighbor’s or a vacant lot? We are powerless to prevent all problems. Is the mulch thick enough? Are there bare spots in the turf? Re-seeding with turf grass seed may be the solution (for a lawn), leaving no space for the seed to germinate. Is the soil healthy enough to support the plant you prefer to grow in that location (cultural methods)?
If it is not acceptable to you that even a new, emerged weed be present in your landscape, start looking over your options. You may decide to jump to the second level: mechanical management (sometimes referred to as physical management) and handpick the weed, cultivate the ground to uproot the weed, or cut off the weed. If the weed is bindweed, a biological method might be used, such as the bindweed mite. You may choose to use the highest level, the chemical level and spray the weed with a soil-safe, non-selective, 20% vinegar solution or other organic herbicide. The step of last resort is using a synthetic, toxic herbicide, often with residual value, and harmful to the soil life (depending on the herbicide).
You have a choice to make; each choice has consequences. Pulling out the weed could bring up buried weed seeds. Cultivating could bring up weed seeds, as well as losing soil moisture, and perhaps destroying roots of vegetables and other ornamentals. If you decide to pull out the weed you might choose to prevent disturbed weed seeds from re-emerging by then applying corn gluten meal to that spot. There are many choices with every problem. If you don’t determine the best appropriate cultural management technique to apply to the problem, the problem will re-occur and you will be faced with jumping to the second or higher levels again in the future.
Cultural practices means our gardening techniques. Most of the problems in the landscape are caused by bad gardening techniques either by omission or practice. The three main areas most gardeners fail are plant choices, soil management and maintenance techniques.
Choosing appropriate plants for the area, which includes disease and/or pest-resistant varieties, is one of the most important decision for avoiding problems in the landscape.
Diverse plantings (companion plantings), resistant varieties, crop rotation, planting in the proper season, and shifting planting times to avoid peak insect periods are cultural methods we can implement to avoid pest problems. Each genera of plants has many species within it. Choose the species or variety best adapted to our climate and soil conditions. For instance, in planting tomatoes, choose varieties with resistance to verticillium wilt, fusarium wilt, nematodes and/or tobacco mosaic virus, shown as V F N and T on the plant label.
A diversity of plants should include pollinator friendly plants to draw beneficial insects into your garden. Plant a variety of plants that pollinators can use, with a variety of flower shapes, colors, habitat, and consecutive flowering seasons. Limit sterile, pollen-less hybrids that pollinators cannot use.
Stable ecological environments have a great many plant and animal species. The more complex the diversity of life, the more numerous and varied are the interactions between and among them. This is good for your garden. "Biological diversity increases biological complexity, which increases biological stability (or balance) . . . Balance is what happens when nature is in harmony with itself." (Grissell, 2001), Balance occurs when the natural order of things is allowed to proceed without our intervention, by using pesticides, for example.
The absence of diversity is one factor that makes your lawn and garden highly susceptible to attack. Monocultures are abnormal. Expanses of single or a few plants make it easier for predators (insect or otherwise) to pinpoint their next meal.
Preparing the soil with adequate organic content and drainage is the second most important principle for avoiding problems in the landscape. Healthy robust plants are the best and natural defense against pests. Amending new planting beds for organic content and drainage, aerating and adding a minimum of one inch of organic matter to existing beds yearly (medium and high feeders) is necessary. Reduce plant stress with proper watering, and soil amendments. Avoid the use of any compost or manure exposed to the class of persistent synthetic chemicals, the pyralids (see section on Killer Compost under the next page Chemicals). A diverse soil life contributes to preventing pathogen infections.
Other common gardening cultural practices to consider in preventing problems:
- Make effective use of microclimates. Properly site plants in the landscape with attention to their requirements: water (hydro-zone your plants), light (sun/shade), wind, soil, and temperature (to minimize freeze damage and sunscald).
- Planting trees, shrubs, perennials, bulbs etc., at the proper depth.
- Use mulch.
- Keep equipment clean to prevent spreading weed seeds, bacterial, fungal and viral problems.
- Avoid injury and damage to trees, shrubs and perennials from construction, mowers, and especially weed trimmers.
- Proper pruning techniques
- Proper use of any chemicals in the landscape; never over-use and misuse.
- Never use the class of persistant chemicals, the pryalids, on your landscape
Hand picking weeds, picking off insect pests and removing infected leaves or plant parts is the best mechanical management method. It is the least intrusive to the environment and least expensive. Pick the weeds before they go to seed. In garden beds, just drop the picked weed on the soil for rapid decomposition and return of its nutrients to the soil, or remove it to the compost bin. If the weed has seeded out, snip the seed heads off and dispose in the trash bin before composting the remainder. There is no need to spray tomato plants if tomato horn worms are present. If you are too timid to pick them, snip them with your garden shears. Check the undersides of leaves, too, for smaller, developing worms.
Spraying a stream or jet of water to dislodge the insects, such as aphids, is a mechanical method harmless to the environment. Inspect the plant on a regular basis; it may be necessary to jet spray 3 or four times during aphid season. Aphids feed on tender new growth. Once leaves harden, aphids cannot pierce and suck.
Use traps to capture pests (but not bug zappers). Setting out dishes of beer is a favorite method to capture slugs and snails. Creating barriers, such as with diatomaceous earth (DE), not salt. If using DE, use only in small areas of your garden; they will kill beneficials as well. Buy the type recommended as an insecticide, not for use as a pool filter. Wear a mask to prevent breathing in the dust particles, which can damage your lungs.
Row covers, fine mesh screens, cardboard and metal collars inserted at least an inch deep and up 2+ inches around certain plants are examples of some other barriers that can be used.
Remove infected plant material to the trash can; don't compost it. Throw out deposits of sap, bark, sawdust and leaves that may contain pathogens or insect eggs. Prune off infected and damaged branches and limbs.
Clean pruners and saws with isopropyl alcohol (rubbing alcohol) or a 10% bleach solution to avoid infecting a plant with the next cut.
Solarization of the soil can be used to kill major weed infestations, insect eggs and pathogens down to an inch of soil. First, till the soil, smooth and irrigate the area to be solarized. Cover the area tightly with a clear plastic cover for at least 4 weeks during the warmest months. The temperature needs to reach at least 140ºF under the plastic. Avoid tilling the soil after solarization to prevent bringing up new weed seeds or pathogens.
Management through biological applications mimics natural control. In a natural, harmonious environment, there is a relatively constant population of pests and pest predators. Disturbances of weather, of the environment (by building or construction, causing change in the habitat) and/or use of pesticides create imbalances of the pest and predator populations. Our area gardens have been subject to all three disturbances from time to time.
Biological management of pests usually means the introduction into the garden of the pest’s natural enemies: living organisms such as parasitoids, predators and pathogens. Most of the natural enemies used are specific to the pests; a few are generalists and attack more than one insect pest. Familiar natural predators are lady bug beetles, praying mantids, katydids, dragonflies, damselflies, wasps, beetles, lacewings, flies, mites, true bugs, earwigs, thrips and ants. Wasps such as the Trichogramma species are parasitoids. Using sprays of BT (Bacillus thuringiensis) bacteria, which are toxic only to caterpillars, and Bacillus popillae for milky spore disease to use against Japanese beetle grubs, are two common pathogen examples. Still another alternative is to introduce beneficial insects that target your specific insect threat. Lady bug beetles, aphid midges, green lacewings, bindweed mites, or beneficial parasitic nematodes are predators commonly introduced.
Promote an inviting environment for your local lady beetles, praying mantids and other predators that are already in your garden. If they find their natural habitat and their source of food, they may stay. A few pests are necessary as food for the predators; otherwise they will either fly off in search of richer hunting grounds, or dine on each other.