Question

Column Cactus   I have a 5' tall Column actus (Cereus Urugauayanus?) with three separate sprouts. As you can see in the attached picture, one of the arms has what seems like a white powder or perhaps scales on it. They seem to fall off to the touch and the underlying plant seems healthy (for the little I've looked so far). The other two arms do not have any issue. We bought the plant several months ago and there was no indication of this problem. Can you identify and recommend a course of action?

Thanks,

Steve

Answer
Hi Steve,

Your Cactus has a mealybug infestation. I'm sure the juvenile mealybugs were there when you bought the plant but in such small numbers that you didn't notice them. There is also a good chance that the infestation has already started to spread to the other columns, as well. So you will need to treat the entire plant.

Mix a solution of 5 parts water, 1 part rubbing (isopropyl) alcohol and a squirt of liquid dish soap in a spray bottle. Then, thoroughly spray the entire plant so that all surfaces are dripping wet. You should cover the soil with plastic or newspaper to keep excess runoff from entering the soil.

If you are thorough a single treatment is usually adequate, but you should be alert for any return of the mealybugs. After the spray dries, you may observe that the carcasses remain in place. They are harmless, but you may want to wipe them away with a soft, damp cloth.

I have written an article on indoor plant pests that I will email for free to you (or anyone else) who sends a request to me at [email protected].

Please let me know if any of this is unclear or if you have any additional questions.

If this information has been helpful, please click the Rate Volunteer bar below and enter a rating and nomination for me. I am a volunteer on this site so Ratings are the only compensation I receive for answering plant questions.

Need more information? Visit my website at:
A link to HorticulturalHelp.com

or email me at [email protected] or call me at 917-887-8601 (EST)
 
Regards,
Will Creed, Interior Landscaper
Horticultural Help, NYC

Visit my website at: A link to HorticulturalHelp.com