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Question:

How do you manage cochineal scale (mealybug infestation) on your Opuntias? It forms fuzzy white patches on the cactus and sucks all the moisture out, making individual pads turn brown and die. I live in a central California high desert environment with hot, dry summers and cold, dry winters (average of 13″ of rain a year). I have two large prickly pear cacti in containers in full sun, one with a severe infestation and the other mild. In the summer I water them twice a week. Now, in the fall I am watering them once a week; in the winter not at all. I have treated them with a sulfur spray and a rosemary-clove spray but nothing seems to work.

Answer:

Mealybugs are such pests! The best solution I’ve found to eradicate them is 70% isopropyl alcohol. Pour this into a spray bottle, and thoroughly spray down the mealybugs where you find them.

Since cochineal scale tend to be a little more “attached” than typical mealybugs, you should also hose down your Opuntia to blast the bugs off as much as possible. This hose attachment set from Bonsai Jack would work perfectly. The brass nozzle is powerful but shouldn’t damage your cacti.

It may be necessary to spray with alcohol again anywhere you weren’t able to remove the scale.

Other people have suggested using soapy water to deal with mealybugs, but alcohol is the best solution I’ve found.  This is also something I go over in great detail in my online course!

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