A soft, often white, fuzzy growth on cacti sparks curiosity. This distinctive characteristic serves various functions for the plant. Understanding this fuzz helps appreciate the unique adaptations of cacti.
What is Cactus Fuzz and Why Do Cacti Have It?
Natural cactus fuzz consists of specialized structures like trichomes or woolly hairs emerging from areoles. Areoles are cushion-like areas on the cactus surface where spines, glochids, and woolly hairs develop. These structures serve several biological purposes.
The fuzz protects the cactus from harsh sunlight and sunburn. It also minimizes water loss by creating a microclimate, decreasing transpiration. Some cacti use these hairs to trap moisture from the air, like fog, for absorption. The fuzz can also deter herbivores, making it harder for animals to access the succulent stem.
Natural Fuzz vs. Pests: How to Tell the Difference
Distinguishing natural cactus fuzz from pest infestations, like mealybugs or woolly aphids, is important. Natural fuzz originates uniformly from areoles, appearing as an integral part of the cactus. It remains fixed and does not spread.
Mealybugs appear as irregular, cottony masses, often in crevices, at spine bases, or on stem undersides. These small, soft-bodied insects (about 4mm long) are covered in a white, waxy secretion. They can move slowly. If prodded, the “fuzz” might smear or reveal the insects, sometimes turning brownish. Mealybug infestations also leave sticky honeydew, which can lead to black sooty mold.
Dealing with Cactus Fuzz
Caution is necessary when handling cacti with natural fuzz, especially species like Opuntia which possess glochids. Glochids are tiny, barbed, hair-like spines that easily detach and can cause skin irritation. Wearing thick gloves, such as leather gardening gloves, and using long-handled tools or tongs can help prevent contact. If glochids embed in the skin, apply white glue or adhesive tape to the affected area, allow it to dry, then peel it off to lift them.
If the fuzz is identified as a mealybug infestation, prompt action can prevent further damage. For small infestations, a cotton swab dipped in 70% isopropyl rubbing alcohol can be used to dab and remove the pests. The alcohol breaks through their waxy coating, killing them on contact.
For more widespread infestations, insecticidal soap can be applied. A solution of a few drops of mild dish soap per quart of water can be used as a homemade option, or a commercially prepared insecticidal soap labeled for plants. Ensure thorough coverage of the plant, including hidden areas, and reapply treatment weekly until the pests are eliminated.