Stubborn Aphids

[Nanotyrannus]

Hi all. I recently discovered that one of my newly purchased herbs was contaminated with aphids. They've jumped to a couple of my downstairs plants, including a Den. kingianum. I've been spraying them every few days with soap solution but they're still kicking.

I want to take this to the next level and just submerge the entire orchid in soap solution to make sure every crevice is treated. Is this advisable? So far the orchid seems unaffected, however I don't know how the roots will react to the soap.

[PaphMadMan]

If you are using an intended insecticidal soap at recommended concentration it should be no problem for Den king. I would flush the pot out with plain water after a day, and repeat the whole procedure after a week even if I saw no more aphids.

If you are using some dish detergent concoction, I would not recommend it.

[katrina]

I've let orchids sit in soapy water for a time w/no negative impact on the plants. When I get new plants or find a heavy infestation on a plant, part of my protocol is to unpot and clean the medium and then let them soak for 15-30 minutes in the soapy solution and then I use a soft toothbrush on the growths to scrub off whatever I can see...including the dried bracts that tend to hide hitchhikers. I've even been known to just soap up a plant and use a soft toothbrush to clean...then rinse well...and into the pot w/fresh medium it goes.

I use dish soap and my preferred brands (due to skin allergies) are Method and Meyer's. I have a friend who used Dawn on her plants w/no problems. Just be sure to rinse them well when you're done.

If the infestation is super heavy, my orchids also get at systemic treatment. Or two. Just to be sure I've gotten them all. I wouldn't use systemic on my herbs but you need to get them off the herbs or keep the herbs away from the orchids because aphids are prolific and you'll keep finding new one until you stop the cycle. A little peppermint essential oilmixed into your soap solution (or Dr Bonner's peppermint soap) is really good for getting aphids on herbs and vegetables. I've heard rosemary essential oil is also good but I've not tried that one myself. Whatever you opt to use...you need to make sure that you're doing treatments repeatedly until you no longer see the little suckers.

I've never had aphids on my orchids but I have dealt w/them in my perennials beds more often than I care to remember.

[Nanotyrannus]

Thank you both. I'm using regular dish soap, but I will look into insecticidal soap if it comes to it. I've just been leaving the soap on the plant - I didn't know I was supposed to rinse it off afterwards! Hopefully I didn't do any long term damage.

I read that the way soaps kill aphids is by washing off their protective coat, which exposes them to the elements. I don't want to risk re-contamination during treatment, so I had the idea of putting each individual plant in a plastic bag. Would that lower the soap's effectiveness?

[desertanimal]

I really like isopropyl alcohol for aphids. A sprayer, a couple days thorough spraying, and then a couple more days when the next generation shows up. It has worked way better for me than soaps.

[katrina]

No need to buy special insecticidal soap ...your mixing some soap, water and maybe even a little alcohol is basically the same thing. And, the DIY is cheaper.

Don't worry about leaving the soap on the plant once or twice...a couple times isn't going to do any longer term damage but I wouldn't want to do it repeatedly over an extended period.

[PaphMadMan]

Dish "soap" may be effective in many cases, but is not at all the same thing as insecticidal soap. It is a much harsher chemical detergent (not soap) to begin with, and may have bleaching or antibacterial components, artificial colors and scents that just aren't necessary, and truly can be deadly to more sensitive plants. Many orchids have tough leaves with a waxy surface, and roots that are adapted to harsh exposed conditions. But jewel orchids, Paphs (roots mostly), many miniatures and any that are sensitive to hard water or high fertilizer concentrations are much more vulnerable, for instance.

Anyone is free to treat their plants as they wish, and dish detergent is cheap, readily available and effective in many cases. But insecticidal soap is designed for the purpose, it isn't expensive, and it is much safer for most plants when used correctly. If you can't find insecticidal soap, then a true liquid soap (Dr. Bronner's and Murphy's are a couple brands available in the US, don't know about other areas) rather than a detergent based product is a better choice.

[katrina]

I guess since I use only Method and Meyers I hadn't thought about the other aspects. Still, a friend has been using Dawn for years with no trouble so I'm sure it's fine for most orchids/plants...provided you don't always leave on the plants. Good points though, paph.

[wintergirl]

I have used Dawn/water/alcohol on many plants without any harm. I have not used it on any sensitive type plants though.

[WhiteRabbit]

I've noticed my kingi can be an aphid magnet - I use rubbing alcohol, or just a stream of water - every few days. When I used soapy solution on buds, they withered.