Introduction to cactus pests: Why they affect you and how to detect them
Cacti and other succulents, known for their ability to adapt to extreme environments, are not exempt from being attacked by plagues and diseases that can compromise your health and appearance. Despite their spines and thick skin, various pests and fungi They find in them a suitable environment to survive and reproduce, especially when the growing conditions are not optimal.
Throughout this article we will address the following: main pests that affect cacti, how to identify them, the chemical and ecological treatments to apply, and the most effective preventive strategies to prevent them from becoming a recurring problem.
Common pests of cacti and succulents
The most common cactus pests can be classified by the type of damage they cause and the part of the plant they affect. It's essential to understand them in order to respond promptly and prevent an infestation that could endanger the plant or the entire collection.
- Mealybugs (aerial and root)
- Mites (especially red spider)
- Caterpillars and ground worms
- Snails and slugs
- Aphids
- White fly
- Trips
- Grasshopper
- Rodents
- Nematodes (microscopic worms)
Mealybugs
They are among the most common and aggressive pests. There are two main types: aerial scale insects (such as scale insects and cottony cushion scales) and root mealybugsThe former usually appear as small brown scabs or white cottony patches attached to the cactus's skin. Root scabs are detected by removing the plant from the pot, identifying white patches on the roots. Both suck sap, weakening the plant and slowing its growth.
Mites and red spiders
Mites, especially the Red spider (Tetranychus urticae), which cause damage by sucking tissue juices. They are detected by the presence of fine webbing, yellow or brown spots, and a dull appearance. They are difficult to see without a magnifying glass and usually attack in dry, warm environments.
Caterpillars and ground worms
Caterpillars usually attack at night, feeding on tender shoots and flowers. Groundworms, on the other hand, damage roots, which can lead to widespread weakening or even death of the plant if not detected early.
Aphids, whiteflies and thrips
Los aphids They mainly attack succulents with rosette leaves (Aeonium, echeveria…), forming visible colonies and excreting honeydew that attracts ants and promotes fungal infections. White fly It is rare in cacti, but can occur under conditions of high humidity. trips They cause silvery discoloration in young shoots and small black spots on the tissue.
Snails, slugs, grasshoppers and rodents
With abundant rainfall or irrigation, snails and slugs can feed on young shoots, leaving visible holes. Grasshoppers and rodents can also devour entire shoots, especially in conditions of food scarcity.
Nematodes
These microscopic worms affect the roots, producing characteristic growths and weakening the plant from the substrate. Although they are difficult to eradicate, their spread can be controlled by removing the plant, removing affected roots, and renewing the substrate.
Fungal and bacterial diseases in cacti
Apart from insects and animals, the mushrooms and bacteria are also a threat to the health of cacti. The damage is usually irreversible, although its progress can be halted with immediate action.
- Root rot (Phytophthora, Fusarium)
- Anthracnose (Colletotrichum spp.)
- Powdery mildew (Oidium spp.)
- Black spot (Alternaria spp.)
- Bacterial infections
Root rot
One of the most serious fungal infections, caused by Phytophthora y FusariumInitial symptoms include brown discoloration at the base, soft tissues, and a foul odor. Affected plants stop growing and quickly collapse.
Anthracnose
It appears as brown or black spots that can merge to form necrotic areas. It develops in high humidity and spreads rapidly in poorly ventilated environments.
Powdery mildew
It creates a powdery white layer on the stems, weakening the plant and preventing efficient photosynthesis.
Black spot
Caused by AlternariaThese dark spots can spread rapidly if the ambient humidity is not reduced.
Bacterial infections
Bacteria usually enter through wounds. They cause softening, necrosis, and emit putrid odors. It is essential to isolate affected plants and remove diseased parts.
How to prevent pests and diseases in cacti
Prevention It's the basic pillar for keeping cacti and succulents healthy. A suitable environment and regular care make it difficult for pests and fungi to establish and spread.
- suitable substrate: Use cactus mixes with excellent drainage, incorporating coarse sand, perlite or pumice to prevent waterlogging that causes rot. Do you know how many types of cacti there are and how to care for them?
- controlled irrigationWater only when the substrate is completely dry. Excess water is the main cause of fungal and bacterial diseases.
- Good ventilation: Essential in indoor and greenhouse crops, to avoid the accumulation of environmental humidity.
- Balanced fertilization: Providing specific nutrients for cacti strengthens their natural immune system, allowing them to better resist attack by pathogens.
- Quarantine of new plants: Keep any newly acquired cactus in quarantine before mixing it with the collection, to detect possible pests and prevent their transmission.
- Frequent inspection: Checking leaves, stems and roots regularly allows for early detection of pest or disease symptoms, making control easier.
- Regular cleaning of the environment: Keeping the area free of plant debris and dirt reduces hiding places and sources of infection.
- Avoid injuries: When handling or transplanting, do so with caution to prevent bacteria from entering through cuts.
Curative and preventive treatments for pests and diseases
When prevention is not enough, the next step is to resort to curative treatmentsThese will depend on the type of pest or fungus present and the degree of progression of the infestation.
Chemical treatments
- Systemic insecticidesThey penetrate cactus tissues and eliminate pests such as mealybugs, caterpillars, aphids, and whiteflies when ingested. Use them in spring and fall as a preventative measure.
- broad spectrum fungicides: For fungal infections, apply to the affected area and even soak roots in fungicide solution in cases of rot.
- acaricides: To combat mites such as the red spider, there are specific commercial products (check labels and respect safety times).
- Metaldehyde or MethiocarbAgainst snails and slugs, apply granules to the substrate; replenish after watering or rain.
Nota: Always apply plant protection products at dusk, avoiding the hottest hours, and use fixing oils to improve their persistence on the plant (especially in summer).
Ecological treatments and natural remedies
- Neem oilEffective as a natural insecticide and fungicide against mealybugs, mites, flies, and mildew. Spray a diluted solution on stems and roots.
- Isopropyl alcoholApply with a cotton swab to mealybugs and cottony cushion patches. Kills on contact, but should be used with caution to avoid damaging healthy tissue.
- Insecticidal soap: Useful for controlling initial populations of mealybugs, aphids and thrips.
- Diatomaceous earthSprinkle on substrate and stem bases. Physically dehydrates insects without leaving chemical residue.
- Sticky traps: They allow to reduce the number of adult flying insects (flies).
- Natural predators: Introduction of beneficial insects such as lacewings or ladybugs for the biological control of pests such as thrips and aphids.
- Bicarbonate of soda: Dilute one teaspoon per liter of water and spray to prevent powdery mildew.
- Beer for slugs: Place containers of beer at the level of the substrate to attract and eliminate slugs and snails in an environmentally friendly way.
Treatment for fungal diseases
If you detect symptoms of rot:
- Remove the cactus from the substrate and cut off any soft or discolored tissue with a sterile blade.
- Let the wound air dry for several days until it forms a callus.
- Apply systemic fungicide to the cut.
- Replant in fresh, dry substrate, avoiding watering until recovery.
In advanced cases of root invasion, it may be necessary to discard the plant to prevent transmission.
Attack symptoms and rapid diagnosis
The key to pest and disease management is early detectionThere are some general symptoms that help identify them:
- Color change (yellowing, brown spots, whitening)
- Necrosis and chancres in tissue
- Soft or watery parts touch
- Abnormal growth (spin, tumors, galls)
- Exudation of substances or gummosis
- Shoot curling or falling
- Presence of visible insects, cobwebs or cotton
- Lumps on roots
If you suspect anything, isolate the affected plant, examine it thoroughly, and proceed with the appropriate treatment.
Nutrition and care to strengthen the cactus
A nourished and vigorous plant is less susceptible to infections and pests. Always use specific cactus fertilizers and apply according to the growing season. To expand your knowledge, you can consult Trichocereus and Echinopsis.
Frequently asked questions about cactus pests and treatments
- Can I use organic products at all stages? Yes, neem oil, potassium soap, and diatomaceous earth are safe for cacti of all ages.
- Can isopropyl alcohol harm a cactus? Only if used excessively or on clean areas. Apply only to the infestation.
- Can pests jump between plants? Yes, so quarantine and preventive isolation are essential when detecting an outbreak.
Proactive care, focusing on monitoring the health of your cacti, controlling watering, and providing a well-lit and ventilated environment, is the best ally against pests and diseases. At the first sign, act quickly using the most appropriate methods, combining organic products and chemicals when necessary, to ensure your cacti grow strong, flourish, and remain resilient and beautiful protagonists of your collection.
