The Q&A Archives: home remedy to ward off bugs?

Question: I have been having an issue with aphids on my President Hibiscus trees and pesticide has only been keeping them off of the flower buds for three days after spraying. I was told to use the home remedy of 2 tsp. dish liquid soad + 2 tsp. vegetable oil per 1 gallon water. I did and the bugs were gone the next day, but a week later 30% of the leaves on the trees were yellow w/ tiny black spots. I also sprayed this solution on my red banana tropical plants and their leaves yellowed as well. Can I use this home remedy on these plants? Do I have the soution mixture right? Did this solution damage the planst or did I overwater?

I really look forward to your response and appreicate your insight. Thank you and have a great day!

Answer: You've experienced one of the problems with homemade solutions - they can be phytotoxic to plants. Commercially prepared Insecticidal Soaps are generally not phytotoxic because the oil is light-weight and the soap is plant derived so doesn't contain detergents. The best bet for you is to purchase an Insecticidal Soap and to use it diligently over a period of several weeks to get every last aphid. Here's the story on aphids - most are females and they give birth to live aphids in addition to laying eggs. This means that you can have several generations in different stages of maturity feeding on your plants all at the same time. So while the Insecticidal Soap will kill those it contacts, those that are not sprayed will continue to give birth to even more generations. So, thorough spraying is important; both sides of the leaves, in the nooks and crannies where stems meet and all around (and in) the folds of the flower buds. If you spray every 3 days for 2-3 weeks, you should knock out the population.

Best wishes with your project!

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