We've received a lot of questions about pest management and chemicals. Hopefully the following information will be helpful. First, we'd like to remind all gardeners that the Community Beds Rules explicitly prohibit the use of any non-organic chemicals. We encourage all gardeners to select OMRI approved products to help manage pest or other issues. Growing organically requires diligence and an understanding of which products to use and how to use them to control pests.
Some common approaches to pest management include companion planting -- for example, planting basil and marigolds with your tomatoes; or planting nasturtium near your squash. Companion plants work to attract beneficial insects or to attract pests away from your crop plants. See this article for more information. Diligent observation of your plants can also help -- if you're able to find and squish clusters of eggs on your squash leaves, for example, you'll avoid an outbreak of dozens of squash bugs.
If you have to resort to chemical approaches (and given how bad the bugs are this season, you might have to), some common OMRI-approved strategies include:
To repel aphids, mix a solution of 1 tablespoon of Dr. Bronners liquid castile soap (unscented is best) with a quart of water and spray the insects you see (try to spray the bugs, rather than the whole plant). Do this every day for a few days and chances are good you'll eliminate aphids. Make certain you're using a soap and not a detergent -- these are different; detergents will strip the natural oils from the plant leaves and cause damage. Dish soap can also help treat other pests like whiteflies and thrips.
Neem oil can be used to repel aphids and many other pests. It has antibacterial, antifungal and insecticidal properties, and is beneficial to earthworm activity. Be certain to purchase a concentrate of 100% cold-pressed Neem oil, and then dilute that according to the severity of your infestation. Mix your Neem oil with some soap to help it emulsify and spray your plants, making certain to get both sides of the leaves, as well as the places where the leaves meet the stem.
To reduce caterpillar damage on brassicas, you can use a diluted solution of BT (Bacillus Thuringiensis). BT is a bacterium found in soils that is toxic to caterpillar larvae. You'll have to spray your plants about once/week while the larvae are active, but it's very effective when applied diligently and will help keep your kale producing all season long. Learn more about BT for pest control here.
Finally, when nothing else seems to work, you can try spraying your plants with spinosad, another natural pesticide derived from soil bacteria. Spinosad will help eliminate cucumber beetles, flea beetles, thrips, and other pests. Be aware, however, that spinosad, unlike Neem or BT, is harmful to bees, so it's really important to use this carefully and spray at a time when bees are less active -- meaning you should apply this spray only very early in the morning or in the evening. Spinosad is also somewhat toxic to earthworms, so be sure to apply carefully only to your plants -- don't drench the soil surrounding your plants. Learn more about using spinosad here.
Thanks for your continued dedication to the use of organic products in the Community Beds! We hope to include more education around pest management soon!