Question
Hi Darlene,

Reading through some of your past answers, I note that you frequently advocate watering plants with undiluted alcohol as a method of fungus gnat eradication. With so many safe, efficacious methods of pest control available, it never would have occurred to me to water plants with isopropyl.

Given that undiluted isopropyl can cause considerable damage if applied directly to the foliage of certain plants, I am surprised by your claim that watering plants with it causes no harm. On the contrary, I would have thought that isopropyl's solvent properties would negatively impact plant roots. Interested to learn more, I will be appreciative if you will direct me to scientific research on the subject. Thank you.

Marilyn

Answer
Marilyn,

I would be very interested in seeing a list of plants that 70% isopropyl alcohol will damage so that I do not use it on those plants. I can only speak about my 17 years of experience. As I said I am not a scientist and that is not a prerequisite of being on the all experts panel. As I said I can only speak from my experience and I mention that in my answers. Have a great day and I hope your beautiful plants never get attacked by insects. I would be interested in exactly what insecticides you feel are safe for use in the home?  Thank you for the debate.

Darlene

Marilyn,

I am not a scientist, I am a master gardener. I have raised 300 or more houseplants every year for the last 20 years. For the last 17 years I have sprayed many of those plants with undiluted rubbing alcohol on the foliage and poured it on the soil. This has included jades infested with mealy bugs. Jades are extremely sensitive to pesticides. I have also recommended rubbing alcohol to a lot of people on All Experts. I have never had a plant damaged from it, not even jades (crassula). I have never had anyone that I advised to use it come back and tell me that it damaged their plants.

Prior to my use of alcohol (I also sometimes use insecticidal soap or dish soap diluted with water.) I used the chemical treatments and killed a lot of plants, especially jades. I also developed extreme chemical sensitivities and I believe the use of pesticides contributed to that. I do not believe pesticides should be used in the home.

I can only speak from my experience but that is extensive, including growing bonsai trees. Rubbing alcohol at 70% dilution which is what you usually buy in the stores has never injured any of my plants. It kills insects on contact but has not injured any of my plants. It has no residual effects so it will not kill insects that come to the plant from any other plants tomorrow. That is why you have to be persistent and apply it regularly for a period of weeks to get eggs that hatch.  I can only speak from my experience.

Darlene