My Cactus Has White Fuzz Spots on It

Cactus plants (family Cactaceae) make easy-to-maintain additions to the home garden as well as to indoor spaces. From low-growing cacti to taller plants that can reach up to 50 feet tall, these versatile plants grow in a wide variety of colors and forms. While cacti are typically healthy plants, they can suffer from certain types of issues. White fuzz spots on your cactus plant are likely a sign of a pest infestation. Be sure to act fast to protect the cactus from severe damage.

Provide regular care to cacti to maintain vigorous plants with a greater resistance to pests. Though cactus plants can handle a lot of neglect, they are not immune to continued poor conditions. Grow your cactus in areas, indoors or out, that offer full direct sunlight for optimal development. Providing ideal conditions goes a long way toward having a healthy plant.

Maintain extremely well-drained soil conditions. While tropical cactus plants thrive on soil that is high in organic content, desert cacti grow best in soil that's not so organically rich. To help support growth, consider adding monthly applications of 5-10-5 fertilizer from June to September. Irrigate cacti as they grow between March and September. Allow the soil to dry out thoroughly between each watering to avoid excessively wet conditions that encourage problems like root rot. Decrease irrigation to once every three weeks during fall and winter as cacti become dormant.

If you notice white, fuzzy spots on your cactus plants, the plant is likely infested with mealybugs. Mealybugs are soft, flightless insects that target plants like cacti. These tiny, slow-moving pests display gray, pink, or white bodies measuring approximately 1/20 to 1/5 inch in length. Targeting succulent plants like cactus and coleus, mealybugs create the appearance of white fuzz on plants because they exhibit a white, cotton-like wax all over their bodies.

As they gather, their groups look like clumps of cotton. This makes them easy to identify visually. Once you know what the problem is you can begin treating it. Try to take action quickly to prevent damage to the cactus.

Mealybugs are sucking pests that remove plant sap from tender plant tissue by piercing it with their mouths. As mealybugs feed, they excrete a sticky-sweet substance called honeydew that falls onto plant parts.

Honeydew promotes the growth of a secondary problem called sooty mold. This growth is fungal in nature, developing into a black-hued mold that covers plant parts, potentially obstructing sunlight from reaching the cactus. Mealybug feeding leads to stunted growth, wilting, loss of plant color and overall decline.

To control mealybugs on cactus plants, remove and destroy severely affected parts, if possible. Saturate a cotton swab with rubbing alcohol and rub the white fuzzy spots off of the plant to kill the mealybugs and manage the infestations.

For severe infestations, apply low-toxicity insecticidal soap or a higher-toxicity insecticide that contains either acephate or bifenthrin, making sure the label doesn't list cacti as plants that are sensitive to the chemicals, which means plants may be damaged by their use.