I recently helped one of my students, Melissa K. of San Marcos, TX install a couple of raised bed gardens in her back yard. Great fun!
Just the other day she arrived at class begging for help...
"Help! Everything in my garden is getting eaten up by something!"
Spraying garden chemicals to get rid of bugs and weeds not only causes health risks, but these chemicals often aren’t even very effective. Initially, they will kill off a lot of pests, but eventually these pests can develop resistance to the pesticide and come back even stronger. Another problem is the side effects many synthetic pesticides can have on unintended targets (think of DDT and birds).
The best plan is to avoid the need to use pest control in the first place by starting with healthy fertile soil, matching your plants to the soil type, ensuring proper sunlight levels and watering conditions, and using appropriate organic fertilization and pruning, when necessary. But, if that doesn’t work there are many alternatives to chemical pesticides that can reduce pests while leaving a healthy environment for your plants, pets and family. Think of defending you garden (and home) from pests as a multi-level deterrent program.
Barriers and repellents help keep bugs out of the garden. They can act like a wall preventing crawling insects from accessing your home or vegetables. For example, by planting carrots in toilet paper rolls (see photo below) cutworms can’t get to them. Plants can provide a living barrier to insects, too. Peppermint, spearmint and pennyroyal naturally deter aphids and ants, so plant them throughout your garden and these pests will stay away.
Simmering cedar twigs in water and then pouring the (cooled) water over plants will deter cutworms, corn earworms and other pests. Snails won’t cross a line of lime, just as ants avoid cayenne pepper or iron phosphate — a natural inorganic material widely used as a nutritional supplement — keeps slugs at bay.
In addition to the many “do it yourself” pest remedies, you can purchase organic pest control products that work on just about anything lurking around the garden or home.
Ladybugs, green lacewings and praying mantis are but a few of the beneficial insects that will prey on the garden pests you don’t want. These “good” bugs can be lured into the garden with attractive habitat (food, shelter and water) or they can be purchased and released into the garden — you’ll still need a healthy habitat for them to survive.
There are many reasons to introduce beneficial bugs into your garden. Over the long term, they are safer and more effective than chemicals, but you’ll need to do a little research first to determine what your specific pest problem is and which beneficial insects to enlist to help. Luckily, the Internet provides a wealth of resources, as does your local extension service or a good quality garden nurseryman. The picture below shows three of the goodguys.
Naturally occurring insect diseases caused by protozoa, bacteria, fungi and viruses, biological pest controls are effective against their target insects but are nontoxic to humans, pets, wildlife and beneficial insects. They are also less likely to build pest resistance than chemical pesticides and they break down quickly in the environment.
One of the better-known biological pesticides is Bacillus thuringiensis (Bt), which is often used against leaf and needle feeding caterpillars. This bacterium is found naturally in soils around the world and paralyzes the digestive tracts of the insects that eat it. It has been around for decades and has been researched and proven to be safe.
Spinosad is an insecticide derived from the bacteria Saccharopolyspora spinosa and can be used as an alternative to malathion sprays. Spinosad has been found to kill medflies, but not the predators that eat them, and it is approved for use on food crops. It also helps control thrips, caterpillars, leafminers, fruit flies, borers, and much more.
A third (of many) biological pest controls is milky spore powder which targets the white grubs of Japanese beetles. When the grubs come to the surface of the lawn to feed (usually May, June, July or August depending on where you live) they ingest the bacteria. These milky spores germinate and multiply inside the grub, killing it.
Natural insecticides are generally botanical, meaning they are derived from plants that have insecticidal properties. Compared to chemical pesticides they have fewer toxic effects and break down much more quickly in the environment. However, they are still poisons so only indulge as a last resort.
caterpillars, gypsy moth, leaf miner, loopers, mealybug, thrips, whitefly
aphids, spider mites, thrips and other sucking insects
aphid, cabbageworm, flea beetle, flies, harlequin bug, leafhopper, Mexican bean beetle, spider mite, squash bug
aphid, cabbage worm, carpenter ant, Colorado potato beetle, cucumber beetle, flea beetle, fleas, Japanese beetle, loopers, Mexican bean beetle, mites, spittlebug
aphid, codling moth, corn earworm, oriental fruit moth, thrips
armyworm, blister beetle, cabbage looper, cucumber beetle, harlequin bug, leafhopper, stink bug
If you are trying to get or keep organic certification be sure to check the Organic Materials Review Institute (OMRI) or the National Organic Program (NOP) for a list of materials approved for organic use in the United States.
Insecticidal soaps and oils are most effective on soft-bodied, sucking insects such as aphids, spider mites, whitefly and mealybugs. While less effective against many hard-shelled, adult insects (such as beetles), they can be used to control their immature larval stages and eggs. As a result, timing the application is an important factor when using these natural insecticides.
The fatty acids in most insecticidal soaps (these are not the same thing as dish soap) penetrate the insect’s outer covering and cause the cells to collapse, thereby killing the pest. Insecticidal soaps must be applied directly to the insect and will not be effective once the insect is dry. Insecticidal soap is considered a least-toxic pesticide and will not harm beneficial insects such as praying mantis and ladybugs.
Horticultural oil is a highly refined paraffinic oil, that once mixed with water is sprayed on plant foliage. It works by coating and suffocating insect pests and their eggs and can be used throughout the year as both a dormant and growing season spray.
d-Limonene, made from the oil extracted from citrus rind, is a relatively new organic insecticide that works by destroying the waxy coating of an insect’s respiratory system. Ideal for use in the kitchen and around the home, d-Limonene can be used to combat fleas, ants and cockroaches. In a recent study, d-Limonene was shown to reduce cockroach populations more effectively than Dursban, the toxic ingredient in Raid®.
Note: d-Limonene is approved by the FDA as a food additive, and is found in products such as fruit cakes, cleaners, air fresheners and pet shampoos.
Often plant diseases can be avoided by ensuring good draining soil and adequate air circulation. But, when that doesn’t work and your plants start to show signs of rust, moldy coatings, blotches, wilting, scabs and rotted tissue it’s time to apply a fungicide.
Sulfur and copper are two organic fungicides that have low toxicity to animals, including humans. However, you still need to exercise caution and read the instructions before applying them. It’s also important to respect their temperature limitations.
A new broad spectrum bio-fungicide that is approved for use in organic production is known as Serenade Garden Disease Control. Containing a strain of Bacillus subtilis, it provides protection against many of the most common fungal and bacterial diseases, including bacterial leaf blight, botrytis, early blight, fire blight, late blight, powdery mildew and scab.
The key is to be able to minimize that damage or disease without harming the beneficial things in the garden, or worse yet, family, friends and pets! In most cases organic is the way to go, far less harmful to people and animals, far less harmful to beneficial garden insects, and most importantly very effective!