An Organic Primer Part 2
In An Organic Primer Part 1, Chris Bond looked at the organic certification of farms, food and seeds. He also provided a general overview of organic gardening practices and soil amendments. In Part 2, Chris looks at the ways growers can control or prevent pests, diseases and weeds using organic practices.
The goal of organic food production is to grow healthy, nutrient-dense crops that are free of insects and diseases without using harsh, synthetic compounds. Read on to learn a few ways this can be achieved in your indoor and outdoor gardens.
Organic Pest Control
Organic approaches to pest control are more widely varied than conventional, chemical ones. Many organic gardeners who do not wish to use any sprays or treatments use a triage approach. If there are only a few pests present and they do not seem to be causing any damage, I suggest doing nothing until action is warranted. If there is sufficient pest pressure to necessitate action, then a variety of approaches can be enacted.
Hand-picking the pests is the least invasive way of approaching organic pest control, but for smaller pests like aphids this can be impractical. This approach is better suited for caterpillars and beetles.
Luring or intentionally releasing beneficial predators and parasitoids into your garden is another effective method of non-chemical pest control. Hundreds of species of beneficial insects feed on, or otherwise use, many of the pest species that plague gardens. Ladybugs are an excellent defense against aphids. They can consume 50 or more a day. Praying mantids and beneficial nematodes are other great mercenaries that can be conscripted into the defense of your food plants. These are often available at local garden centers, or can be obtained online or through mail order.
Plant-derived solutions and sprays registered for use with organic gardening are also available. Two common active ingredients are pyrethrins, derived from the chrysanthemum plant, and neem oil, from the Azadirachta indica trees of India and Africa. Both of these ingredients are commonly found in commercially available sprays labeled as organic. They often kill pests by smothering their bodies or inhibiting their respiration or other vital functions.
Watch for man-made versions of natural compounds. For example, pyrethroids, which are a man-made version of pyrethrins and are not compatible with organic gardening. To further complicate the matter, some sprays contain certified organic active ingredients, but their delivery method is not compatible with organic gardening, such as in the case of many propellants. If all else fails, remember to look for the OMRI label to know for sure if a product is indeed organic.
Finely ground, fossilized diatoms, known as diatomaceous earth, is another useful insect control measure for the organic gardener. Spread around the base of plants, diatomaceous earth inhibits many crawling insects such as snails and slugs as it will cut them open as they travel across it. If a plant is so infested by pests that treatment will be extensive, it is usually better to remove the plant entirely and dispose of it in an area far away from the others, rather than spray it with chemicals.
Organic Disease Control
The same triage-like approach used by some organic gardeners to combat pests can be applied to organic disease control as well. Some common diseases such as powdery mildew are unsightly, but essentially harmless to plants. Other diseases such as the bacterial wilts on cucurbits (cucumbers, squashes and pumpkins) cannot be treated to a salvageable point once the disease has set in. In these cases, it is best to remove the plant and all of its debris so it does not decompose and go back into the soil.
Good old-fashioned baking soda is an effective control for many fungal diseases, including powdery mildew and some leaf spots. Mix 1 tsp. to 1 tbsp. of it with 1 gal. of water. Include about a half teaspoon of mild soap to help the baking soda stick to the leaves. Mix it well and spray it on the upper and lower surfaces of the leaves. It can be sprayed once every seven to 10 days until the fungus is under control. Any solution with more than 1% baking soda can burn the leaves due to the salt content. A little goes a long way.
Copper and sulfur have been an effective disease control on many food plants for decades. When combined with lime and water, it is known as Bordeaux mix. It can be sprayed on fruit trees, berries, grapes and even ornamentals in the winter to prevent many fungal and bacterial pathogens. Many plant diseases are spread by insects. An effective approach to prevent plant diseases is to combat the pests that spread them.
Organic Weed Control
Weeds are as much of a nuisance for organic gardeners as they are for conventional gardeners, but organic gardeners have many more options to combat weeds than merely using a glyphosate-based weed killer.
Smothering weeds, outside of hand-pulling them, is generally the best option. Numerous mulching options exist. Bio-degradable plastic, which is corn based and has come onto the market in the last few years, is a great option as it can be placed in the garden like traditional plastic. It has the added benefit of degrading over the course of the season so there is no additional labor in pulling it up at the end of the season.
Other viable options include cardboard, newspaper, shredded paper, craft paper, scrap paper, straw (not hay), hardwood mulch (aged), wood chips (aged), compost, leaves and grass clippings. Any paper products used as weed control should be wet down once in place so that they do not blow away.
The inks used on the paper were at one time a legitimate concern, as many were metallic based, but now most are soy or vegetable based.
Planting a cover crop around your desirable crops is an even better option. A crop such as white clover will fill in quickly, out-compete the weeds, can be walked on and adds nitrogen into the soil. An added benefit of the clover is that it is a great food source for honeybees, which will be attracted to your garden and improve the pollination of your other food plants.
For those who absolutely must kill weeds, there are solutions. Vinegar, either of the type obtained in a grocery store or of the horticultural variety, is an effective foliage killer. This is a non-selective approach and any foliage the vinegar makes contact with will be affected. Do not use on a breezy day to avoid unwanted drift.
Boiling hot water is an effective foliage killer as well, as long as the same precautions are adhered to as with the vinegar. Either method might have to be used repeatedly until the desired results are achieved because neither of these methods is likely to affect a weed’s roots.
You will need to cause the roots to deplete their stores to eradicate them. The continual replacement of the foliage will wear them out in due time, and there is no negative residual soil activity with either of these methods.
A controlled flame can also be used to burn the foliage of weeds. Several products, known as flame weeders, are available on the market. As with handling boiling water, the same precautions should be taken when using an open flame.
There are commercial, organic weed killers as well. Granular ones often contain corn gluten as their active ingredient. Immediate results should not be expected with these products, but continued use over time will result in a reduction of weeds. The corn gluten acts as an inhibitor of both root and seed development. It has the added benefit of adding nitrogen to desirable plants.
Other products include plant and fruit oils such as citrus to kill weeds. Apply the same precautions with organic weed killers as you would with conventional ones, which includes using the proper and required personal protective equipment.
A final approach to organic weed control is to intentionally plant or allow weeds that benefit your garden.
Learn more: Advantages of Organic Weed Control
This may seem counterintuitive, but some weeds in your garden are actually a good thing. They provide food and shelter for beneficial insects and their offspring, and they help keep the soil temperatures even and more humid. Many common weeds are actually edible and a great source of nutrition. Dandelions, purslane, mint, garlic mustard and chives are all a great addition to salads and pastas. If you can’t beat ’em, eat ’em!
The definition of organic varies from context to context. It is generally agreed upon by both professionals and practitioners that the goal of organic food production is to grow healthy, nutrient-dense crops that are free of insect and diseases, without using synthetic compounds and with as few natural or organic ones as is possible. In the end, healthy soils will produce healthy plants, which bear forth nutritious fruits and vegetables.
In case you missed it...check out An Organic Primer Part 1!
Written by Chris Bond | Certified Permaculture Designer, Nursery Technician, Nursery Professional
Chris Bond’s research interests are with sustainable agriculture, biological pest control, and alternative growing methods. He is a certified permaculture designer and certified nursery technician in Ohio and a certified nursery professional in New York, where he got his start in growing.