Mealy Bug Infestation on Beaucarnea - recurrent

Calgary, Canada

First post to DG though I have been using/lurking on this site for plus 10 years. I have a vast indoor garden (which lives outdoors in the summer). Have had problems with mealy bugs over the past two years on Beaucarnea, Hoya and Hibiscus but thought I had the problem licked using 50% Isopropyl/ Orange Pekoe Tea [20 bags are soaked in 1 liter of 50%]. Recipe was given to me by retired Hort teacher. Tried Safer Soap in past with poor results.
Just brought my 'babies' in from the backyard and the Beaucarnea has mealy bugs down into the crown on both plants[same pot]. Some are very tiny but there are quite a few that are mature. I usually don't see these until Jan/Feb. Had though to remove the center crown on both plants, but concerned that will affect the meristem and kill the plants. In web searches have found mention of completely removing the leaf crown, covering the cut with wax and waiting for new growth, though nothing is mentioned after that.
These two plants (along with Hoya, Hibiscus, Sanservia) came with me from West Palm Beach, Florida in 1981 when I moved to Calgary as a newly-wed and have done well until the past few years. Stems are now abt. 26" and with foliage, abt. 3 feet tall. Soil is 50/50 sterile beach sand & potting soil.
Has anyone completely removed the crown from a Beaucarnea with positive results? Mealies appeared to travel from Beaucarnea to Hoya and Hibiscus in the past, so I believe Beaucarnea is the primary target. Other suggestions for treatment are appreciated.

Baja California, Mexico(Zone 11)

You can behead the plant (I've seen the results of this but not tried it myself), however I don't see that as a solution as the bugs will probably just migrate to the new head.

The best thing to try right now would probably be a systemic insecticide (like imidacloprid, available under various brands including Bayer). The plant takes it up and it works from the inside, making the plant toxic to insects who try to snack on it. I use the pesticide only after I have tried manually removing the bugs with soap water. The reason why I say try it now is that it works best when the plant is most active (growth season) because the roots have to take it up into the plant to make it work. During the winter with low light (probably one of the causes of your problem) the plant is sort of sleepy and not as active.

To get the soap to work, you really have to blast the soap stream into every nook and cranny to hit all the bugs you can see (and a few you can't). It's not that toxic to them but once you dislodge the bugs they tend to be gone. Often a second or third treatment is needed to get the leftovers. No big deal because the soap is not toxic to the plant and the effort is minimal.

In my experience mealies tend to show exactly the same kind of preference you describe, homing in on their favorite targets time after time, so vigilance is the best approach to keeping them under control. Often a serious problem is a sign that you need to adjust something about how you're growing the plant, but obviously your options are limited when they have to come inside for the winter.

Hope this helps.

Reno, NV(Zone 6b)

I used Beyer 3-In-1 Insect, Disease & Mite Control. My Beaucarnea had a terrible case of mealy bugs for years. I battled them with insecticidal soap and Bonide before giving up. In desperation, I drenched the plant with the Beyer 3-in-1 three times in one day - every time more bugs climbed up to replace their fallen comrades. That pretty much got rid of them.

I suspect the Bonide didn't work because Beaucarnea aren't kept damp enough as it did work on everything else that had mealies. Use the Beyer 3-in-1 in a well ventilated area and wear a mask. It seems to be effective until the foliage gets wet or about 30 days.


Baja California, Mexico(Zone 11)

The simple insecticide sold by Bayer (I use a bottle labeled Fruit, Citrus & Vegetable Insect Control) has the same active ingredient, minus the two other ingredients, which are irrelevant to mealy control. Unless you're concerned about other diseases, and especially indoors, I would choose the product labeled specifically for insects.

Decatur, GA

I have use a liquid dishwashing detergent and water solution (make it strong, 1/8 cup per gallon) in a container big enough to submerge your plant, pot and all. Leave it for 10-30 minutes and then rinse thoroughly. I've saved a curly leaved Hoya doing this that had been badly infected with mealy bugs for years. You can reuse the solution over and over.
Its not too practical for really huge plants but will immediately clear up the problem.
I have also used imidacloprid systemically with really good results. Its labeled for outdoor fruit trees or something so its a total off label use on indoor succulents. If I am diligent it keeps my Adeniums, orchids and other caudiciforms clear of mealy bugs all winter. I use approx. 1- 2 teaspoon per gallon of water and apply it to the roots/growing medium about once a month. - I think I got this dosing from a former DGer who honestly said she was guessing about how much and how often. I followed her advise.
Good luck. Mealy bugs are a pain.

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