Answer: As you've discovered, some plants are susceptible to leaf burn whether the product is organic, homemade, or manufactured. It's the oil that, when it coats the leaves, can effectively block the exchange of oxygen (leaves can't breathe). I've had this happen with tender leaved plants such as fuchsias and roses. The best course of action is to first read the label and make sure that both the targeted pest and the host plant are both listed. If it is not safe to use on a plant, that plant will not be listed on the label. If I use compounds on plants I know have tender leaves I wash the product off after 15 minutes. This usually keeps the leaves from burning. Also, don't apply oil based products in the hot afternoon sunshine. Use them in the early morning or early evening and wash them off after 15 minutes.
Your plants will recover, but they'll take some time to grow new leaves.
Best wishes with your garden!
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