Alcohol as a pesticide

Shmuel · Post by **Shmuel** » Mon Sep 13, 2010 8:26 am

As Iann mentioned alcohol in his post on my sulfur thread, I thought I would open it up on a thread of its own.

It is well known that a dab of alcohol spells death to a few mealy bugs. I have a number of questions on alcohol though.

1) Is a cotton swab applicator really the way to go, or can a squirt from a medicine dropper be dribbled into the crown of the plant or down crevice, etc?

2) The old phytotoxicity issue. Obviously not to do it in the sun, but can the whole plant be sprayed with alcohol?

3) which alcohol is best? Here one can purchase 70% isopropyl or 95% ethyl alcohol. The ethyl is much cheaper by the liter (used for home-made liquors like coffee etc

) Should it be used straight or diluted?

4) I saw a formula for a spray which is a combo of alcohol, 409 cleaner, and water. Also I saw one that suggested combining the alcohol with an oil, such as neem. Anyone have experiences with this?

I would really love to use alcohol as it is handy, easy, not so toxic to me or other critters (besides the bugs), and disappears quickly without residual smell. Your thoughts and experiences are highly appreciated!

Shmuel

Avirosa · Post by **Avirosa** » Mon Sep 13, 2010 4:02 pm

I have used methylated spirit both as a spot treatment and sprayed on (sprayed to the point of run-off) if the mealies are harder to reach. Neither has had any adverse reactions from the plant, though i am always carefull not to apply in sunlight.

Post by **daiv** » Wed Sep 15, 2010 4:54 pm

I have tried it on mealy bugs and have not found it to be very effective. The fuzzy coating on the bugs makes it hard to actually spray the bugs. I noticed that most of it just evaporates off. It also seems ineffective against eggs. I give my plants a once per year systemic treatment and have never had problems since!

Wallydraigle · Post by **Wallydraigle** » Wed Sep 15, 2010 10:28 pm

I always just go nuts with a spray bottle. I use isopropyl alcohol. 70%, 99%, just whatever I have. I've never had a problem with it not killing mealies, but I really let them have it. It's cheap, and it evaporates in a minute or two, so why not?

Shmuel · Post by **Shmuel** » Thu Sep 16, 2010 8:20 am

Daiv said:

I have tried it on mealy bugs and have not found it to be very effective. The fuzzy coating on the bugs makes it hard to actually spray the bugs.

I saw one formula that was a combination of alcohol and 409 cleaner (is that the same as what the call "Fantastic"?) The 409 was apparently to be like an insecticidal soap. I think soaps and alcohol mix well - that could be a great combination to get at the critters.

Daiv said:
I give my plants a once per year systemic treatment and have never had problems since!

I have used the systemic out of desperation, but I really like to keep the chemicals to a minimum. I also understand your plants in a greenhouse need different treatment. I should have taken a photo of a really wild-looking some-kind-of-ladybug larva crawling on a plant I was about to spray and poking into all the crevices for some scale or mealy to eat. I would hate to bast them with a general spray. Also we have a lot of sunbirds around the garden (The Israeli / African equivalent of hummingbirds) and I would hate to have them sipping toxic nectar. Also the systemic (Ibosomethingclonimid?) was really expensive.

I like having as many weapons in my armory as possible. What I am looking for is an easy non-toxic to me solution (pardon the pun) for quick fixes that won't necessarily be 100%, hence this alcohol thread.

By the way, in LA many years ago the pesticide of choice for cacti was Cygon 2E. I don't know if that is still around, but I have an old bottle of it and have used it with no phytotoxic problem at all.

Shmuel

Day · Post by **Day** » Sat Oct 16, 2010 2:01 pm

I just discovered mealy bugs on my Mammilaria rhodantha ssp. pringlei, between the thorns. It's a young plant so I'm really concerned, hope this will help, I will buy some 70% to 90% ethanol, and try to spray it on the little bastards.

Does ethanol damage the plants? if it gets in the soil?

Shmuel · Post by **Shmuel** » Sun Oct 17, 2010 7:44 am

Day wrote:

Does ethanol damage the plants? if it gets in the soil?

Alcohol seems to act as a dessicant - it dries out things and sucks out the water.

I suggest watering the plant first - generally pesticides should not be applied to dry plants. Also, I do it at night so the plant has dried before any sun gets there. I still keep them out of direct sun because I am paranoid of phytotoxicity.

I am nervous about roots and alcohol, that's a reason to water first. But it may have no effect there. I just don't know. If ti is just the runoff from spray, I would not anticipate a problem.

The biggest difficulty seems to be the waterproof coating of mealybugs. It could be adding a little soap will help to stick. Also, it seems that an acidic spray is more effective than an alkaline one, but I don't know the pH of alcohol. I also don't know what would happen if one adds a bit of vinegar to the alcohol...

I have mealy monsters on some Agaves that I plan to alcoholize - I hope to report what happens.

Good luck, Day. Keep us posted what happens.

Shmuel

Day · Post by **Day** » Sun Oct 17, 2010 2:20 pm

I really suck at waiting, so I took a pierce of wire, and started killing the little buggers in between the thorns. it's sunday so I can't go and buy a bottle of ethanol, however I have some antibacterial gel, which contains 85% alcohol. So I applied a blob of gel at the top of my mammilaria, and then air blew it into the cracks all over it.

I hope it wont kill my plant, but I simply can't watch and do nothing.

The size of my mammilaria:

Harriet · Post by **Harriet** » Sun Oct 17, 2010 5:34 pm

I'd be as worried about the "green goop" as the mealies. Is your container draining well enough?

Day · Post by **Day** » Sun Oct 17, 2010 10:13 pm

Harriet wrote:I'd be as worried about the "green goop" as the mealies. Is your container draining well enough?

Well I'm a little new to the whole right soil thing, so I'm not sure how well it needs to drain, but I usually only water when it's dry all the way through.

What I do know though is that it's not the ideal soil, I has worked for now, until I get some sand to mix into it.

Anyways, I'm thinking the green stuff is algae, don't know if that can affect it somehow.

iann · Post by **iann** » Sun Oct 17, 2010 10:39 pm

The green goop almost certainly is algae. It is inevitable when you put moist soil into a transparent container. Water plus light = green! It isn't horribly toxic or anything, but best to try and avoid the conditions that cause it. Orchids might need light on their roots, but cacti don't

Day · Post by **Day** » Mon Oct 18, 2010 7:11 am

iann wrote:The green goop almost certainly is algae. It is inevitable when you put moist soil into a transparent container. Water plus light = green! It isn't horribly toxic or anything, but best to try and avoid the conditions that cause it. Orchids might need light on their roots, but cacti don't

Yeah, I should probably put something around to shield for the light. In general, maybe I should just get a hold of real plant containers instead of buttom half bottles

Edit: On a positive note, the alcohol seems to have worked on the mealy bugs, now it's just a matter of time to see if it unfortunately also has affected the plant.

madadi · Post by **madadi** » Sun Jan 23, 2011 6:34 am

i would be worried about using the gel because it will leave too much of a residue. if there is algae in the soil its most likely staying too moist and for an adult plant it could be dangerous, especialy around the colder months.