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How to Grow: IPM for Organic Pest Controls
No matter how well you grow your foodscape plants, eventually other critters, insects and diseases will want to enjoy them as much as you. Certainly a healthy, well watered and fed plant will be able to withstand attacks better than one that is struggling. But you should be ready to prevent damage and then jump in early to reduce a problem once an attack happens.
I like to follow the integrated pest management (IPM) approach to foodscape gardening. In this approach you rely on techniques such as planting resistant varieties, using crop rotation, erecting barriers, using proper sanitation, and installing traps before resorting, as a last defense, to sprays. When you do spray there are a number of organic sprays on the market that are less ha
rmful to the environment, wildlife, pets and people and still effective at controlling problems.
When a problem arises, it’s good to spend a little time sleuthing before reaching for a spray. Often plants can withstand a little damage and grow fine. You might be fine with a little scarring on an apple or some tunneling on a spinach leaf.
Here are the steps you should go through once you find a problem worth solving in your foodscape.
1) Identify the Problem– Take a close look at the damage and try to assess what’s the cause. Just because a certain beetle is hanging around the damaged leaf, doesn’t necessarily mean it caused the damage. Look for insects and eggs on the plant with the damage. Look around for animal footprints in the soil. See if other plants have similar damage. Look for patterns of damage that will tell you who the culprit might be. Sometimes damage may be caused by hail, rain or frost and look like it’s an insect or disease attack. All of this sleuthing may require a little research or at least help from a more experienced gardener to identify the possible suspects.
2) Know They Enemy– Once you’ve figured out who or what is causing the damage then you need to understand how that creature works. Where does the insect lay its eggs and what do they look like? I’ve easily controlled squash bug infestations by diligently squishing the eggs every few days on the underside of my zucchini and winter squash leaves. Does the disease thrive under wet conditions? Consider thinning out branches or removing plants to increase airflow to make a less friendly an environment for a disease. Where does the animal doing the damage live? If you can find where it likes to live you can alter the environment to make it less hospitable. For example, chipmunks and voles love living in woodpiles and stonewalls. Not planting close to these may limit some damage.
3) Cultural Controls- Integrated pest management works best when you have healthy plants. But there are other strategies that work well, too. Rotate crops not planting the same family of crop in the same location for at least 3 years, to reduce any disease and insect build up in the soil. Plant a diversity of flowers, veggies, fruits, and herbs to attract and provide habitat for beneficial insects. These will help keep an errant insect and disease population in check. Clean up the damaged plants well in fall so insects and diseases are less likely to over winter and reinfect plants next year.
4) Mechanical Controls- Once you realize you need to do something more aggressive to control a pest, look at creating barriers and trapping. You can often block damage before it happens by covering susceptible plants with a floating row cover to thwart egg laying of insects, such as squash vine borer, or placing cardboard collars around stems to prevent cutworm damage. Handpicking individual insects, crushing eggs and spraying small insects off the foliage with a blast of water from a hose are sometimes the easiest and most effective way to stop a big infestation before it gets started. Sometimes removing a diseased or damaged plant early on will prevent the problem from spreading to other plants. For animals, nothing beats a good fence to keep bunnies, deer and woodchucks out of your foodscape or netting to keep birds off the blueberries and cherries.
Traps can be another effective way to reduce the damage. There are traps for a variety of insect pests such as Japanese beetles, apple maggots and cucumber beetles. Although they don’t provide 100% control, they will go a long way to reduce the invading population.
5) Sprays- If you’ve tried all of the above techniques and product ideas and still can’t reduce your damage to an acceptable level, then you may have to resort to organic sprays. Always follow the label directions as to what plants you can spray, when and how to spray a specific pesticide. The first line of defense is preventive sprays. These sprays deter pests by stopping them before they’re a problem or making the plant unappetizing to the pest. Dormant and summer oil sprays are used to smoother eggs and shelled insects such as scale. Use these at the appropriate time for your plants. Kaolin clay covers the leaves with a light clay coating that makes it hard for insects such as flea beetles to get started. Some oils, such as Neem oil, may not kill insects and diseases but create an environment they don’t like or interrupt their lifecycle to thwart their feeding.
Animal repellent sprays make a leaf or plant bad tasting or smelling for your critter. These are best used in combination. Use 3 or 4 different types, containing products such as rotten eggs, garlic, cayenne pepper, dried blood, and predator animal urine, and rotate them every few weeks so the animal doesn’t get used to the scent or taste. Reapply as plant grows and after heavy rains.
Baking soda, copper and sulfur sprays are often used as deterrent to diseases such as powdery mildew, black spot and blight. It’s best to use these early on in the infestation to be effective.
If you really need to kill an existing insect or disease, then you may have to use other sprays. Try to find sprays that are targeted to that pest. In this way you’re less likely to harm beneficial insects and other creatures in the garden or soil. Biological sprays, such as Bacillus thuriengensis (Bt), come in many forms to specifically kill certain insects. One form kills cabbageworms, tomato hormworms, tent caterpillars and another kills insects in the Lepidotera or caterpillar family. Another type of Bt kills Colorado potato beetle larvae. And yet another kills mosquito larvae. Look for the form that you need in your garden. Some microorganisms have been found to kill other microbes or insects. Bacillus subtilis (Serenade) is a bacterium that fights fungus such as powdery mildew and black spot. Spinosad is a bacterium that kills a wide number of insects such as spider mites, stink bugs, tent caterpillars, fruit tree borers, and many beetles. Insecticidal soap is a home and commercial remedy that kills a number of insects such as aphids, thrips and Japanese beetles.
Broad-spectrum organic pesticides, such as pyrethrum-based sprays, should be a last resort in the garden. These kill a wide range of good and bad insects. It’s a good example of a spray that although organic, is still a pesticide and has to be treated with respect. Even seemingly safe insecticides, such as spinosad, can harm hone bees so should be applied in the evening or when bees are less active
By using a combination of these IPM techniques, you should be able to prevent problems before they happen or slow them down long enough to get a good harvest. All the time, you still can feel safe about the healthy food you’re growing and feeding your family.
Excerpted from the book, Foodscaping, (CSP, 2015)