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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.