Trichocereus: guide to identifying invisible pests

# Trichocereus: guide to identifying invisible pests

In the professional cultivation of **Trichocereus** (syn. *Echinopsis* for many authors), a critical part of success is timely detection of **“invisible” pests**: tiny, subterranean, or cryptic organisms that go unnoticed until damage is evident. This technical guide from TRICHOLAND compiles diagnostic criteria, differential signs, and integrated management protocols for the most common and difficult-to-see pests in Trichocereus, both in collections and nursery production.

The goal is for you to confirm or rule out their presence without a professional microscope, apply safe corrective measures, and scale control effectively and sustainably.

Early signs: how a Trichocereus “reads” when there are invisible pests

• →**Bronzing or “russeting”**: loss of bright green, with fine browning and rough/superficial corkiness. Typical of flat or false mites (*Brevipalpus*).

• →**Silver/matte with fine speckling**: opaque, “sanded” appearance, often with black dots (excretions). Compatible with **thrips**.

• →**Diffuse chlorotic spots** that expand without a defined pattern, sometimes accompanied by slight epidermal sinking: compatible with **mites** (Tetranychus, eriophyids).

• →**Deformation of the apex**, “stunted” shoots, or abnormal branching (witches' broom type): indicative of **eriophyid mites** or **broad mite** (*Polyphagotarsonemus latus*).

• →**Growth halt without apparent cause**, general yellowing, and loss of turgor that does not improve with watering: suspicion of **root mealybug** (*Rhizoecus*) or root problems.

• →**Ribs that “fade”** (soft tissue due to excess N) and microlesions: facilitate the establishment of mites and mealybugs.

• →**Ants lurking** around the pot/neck: often associated with **mealybugs** (they feed on their honeydew or protect them).

• →**Absence of honeydew/sooty mold** with severe damage: points towards **mites** (they do not excrete honeydew), not towards aphids/mealybugs.

Quick diagnostic tools and methods

• →**10–20× magnifying glass**: essential. Check apices, areoles, grooves between ribs, and the neck of the plant.

• →**“Tapping” test**: place a white cardboard under the stem and gently tap; observe with the magnifying glass if reddish/brown moving dots (mites) or elongated (thrips) fall.

• →**Transparent adhesive tape**: press on the suspicious area, stick it on a white sheet, and check with a magnifying glass; useful for seeing mites/thrips.

• →**Sticky traps**: yellow (general) and blue (thrips), at rib height; check weekly.

• →**Root inspection**: if there is decline without apparent cause, unpot the plant; look for white cottony masses on roots/“neck” (root mealybug).

• →**Washing-sifting** of the root ball in a bucket with warm water and mild soap; filter the water through a white mesh to detect root mealybug.

• →**Homemade Berlese** (advanced): for soil; a source of light/heat expels microarthropods into a collector with alcohol.

• →**Macro photography** with mobile + magnifying glass: allows for weekly evolution comparison and seeking a second technical opinion.

Most common invisible pests in Trichocereus: identification and management

1) Root mealybug (*Rhizoecus* spp. and related)

**Why it is “invisible”**: lives buried or in the neck, protected by substrate and root debris; not always seen on the surface.

**Symptoms**:

• →Plant that “stops,” yellows, and loses vigor despite correct watering/fertilizers.

• →Stem that moves in the pot (damaged roots, weak anchorage).

• →Ants in the container; on roots, white cottony masses and small grayish oval insects.

**Confirmation**: remove the plant, shake and wash roots; observe under a magnifying glass for mealybugs on fine roots and neck.

**Management**:

• →**Physical shock**: moderate pressure washing of roots + bath in soapy solution or with *horticultural oil* at 1% (never in full sun or heat).

• →**Repotting** into new substrate, disinfected pot. Remove 100% of old substrate.

• →**Systemic drench** where authorized for ornamentals: active ingredients registered against mealybugs (consult local regulations and label). Repeat every 14–21 days.

• →**Biological control**: *Cryptolaemus montrouzieri* (mealybug predator) and soil mites (*Stratiolaelaps/Geolaelaps*) as adjuncts.

• →**Ant control** with specific baits to cut off the protection/mobility of the pest.

2) Two-spotted spider mite (*Tetranychus urticae*)

**Invisible** to the naked eye when the population is low; thrives in heat and low humidity.

**Symptoms**:

• →Loss of shine; fine yellow mottling; brown “dust” to the touch.

• →Subtle webs between areoles in strong attacks (not always present).

**Confirmation**: tapping on cardboard; see reddish/brown dots moving. 20× magnifying glass reveals individuals and eggs.

**Management**:

• →**Cultural**: gentle morning showers in summer outdoors; slightly increase RH in the greenhouse with ventilation; avoid excess N.

• →**Biocontrol**: *Phytoseiulus persimilis* (quick on shoots), *Neoseiulus californicus* and *Amblyseius andersoni* for preventive management.

• →**Specific acaricides** rotating *IRAC* (e.g., abamectin, bifenazate, etoxazole, hexythiazox, spiromesifen, spirodiclofen) according to local registration; add appropriate **wetting agent** and cover grooves and areoles. Avoid oils in high temperatures.

3) False or flat mites (*Brevipalpus* spp.)

**Profile**: extremely small, without webs; cause **russeting**/corkiness and progressive browning.

**Symptoms**:

• →Brown, rough areas that advance from shaded areas and inner ribs.

• →Visual loss of turgor without collapse; in chronic attacks, leave permanent scabs.

**Management**:

• →**Detailed monitoring** with a magnifying glass in cool hours.

• →**Biocontrol**: *Amblyseius swirskii*, *N. californicus* as preventives in controlled environments.

• →**Contact and translaminar acaricides** effective in rotation (see list above); administer in 2–3 passes every 7–10 days to cover hatchings.

4) Eriophyid mites (family *Eriophyidae*)

**Profile**: microscopic, worm-like; attack meristematic tissues and areoles.

**Symptoms**:

• →**Growth deformation**, “swollen” areoles, abnormal short shoots (witches' broom type), fine superficial scars.

• →In young plants, “wrinkled” appearance of the apex without water-related cause.

**Management**:

• →Remove deformed microshoots in localized attacks.

• →Rotate **ovicide/juvenile acaricides** and translaminar (etoxazole, hexythiazox, abamectin), with excellent coverage of the apex.

• →**Biocontrol**: *Amblyseius swirskii* and *N. cucumeris* as preventives in temperate climates.

5) Broad mite (*Polyphagotarsonemus latus*) and cyclamen mite

**Profile**: apex pests; tiny; injure young tissues.

**Symptoms**:

• →Thickened apices, halted and “wrinkled” growth, areoles emitting deformed spines.

• →In rooting cuttings, halts the emission of aerial/areolar roots.

**Management**:

• →Environment: avoid chronically high RH and stagnant heat without ventilation in the greenhouse.

• →Acaricides/miticides compatible with tarsonemids (abamectin, systemic spirotetramat where authorized, etc.).

• →Biocontrol: *N. cucumeris*, *A. swirskii*.

6) Thrips (*Frankliniella occidentalis*, *Thrips tabaci*)

**Profile**: thin, very fast; hide in grooves and flowers.

**Symptoms**:

• →**Silver** or “frosted” surface, with **black dots** (excrement) and scratch lines.

• →Slight deformation of the apex; severe aesthetic damage in seedlings and young ribs.

**Confirmation**: blue traps; tapping reveals elongated yellow/brown insects.

**Management**:

• →**Hygiene and insect-proof nets** in greenhouse openings; remove old flowers.

• →**Biocontrol**: *Orius laevigatus*/*O. insidiosus* (adult and nymph predators), *A. swirskii* or *N. cucumeris* for juvenile stages.

• →**Insecticides** rotating *IRAC*: spinosad, ciantraniliprol, acetamiprid or other authorized for ornamentals; apply interspersing every 5–7 days and with wetting agent.

7) “Scale” mealybugs (Diaspididae/Coccoidea) camouflaged

**Profile**: hard or waxy plates stuck to the epidermis, the color of the stem; nearly invisible mobile nymphs.

**Symptoms**:

• →Yellowish circular spots that evolve into brownish patches; sometimes with honeydew/sooty mold (in coccoids).

• →General decline if there is colonization of the neck.

**Management**:

• →Manual removal with a swab and 70% isopropyl alcohol in initial foci.

• →Mild horticultural oils in cool weather and shade; avoid burns in full sun/heat.

• →Systemics/IGRs (e.g., buprofezin, pyriproxyfen, spirotetramat) according to local registration; repeat and alternate modes of action.

• →Biocontrol: *Cryptolaemus*, *Anagyrus*, *Metaphycus* in professional programs.

Differentiate pest from disease or physiopathy

• →**Sunburn**: cork-brown plates well-defined after a sudden change to full sun. There is no speckling or excrement. Prevention: gradual acclimatization with 40–50% mesh.

• →**Edema**: blisters/corking due to watering with cold substrate or hydration spikes; does not progress with biocontrol or insecticides.

• →**Nutritional deficiencies**: regular interveinal chlorosis (iron, magnesium) without scratching or rough browning. Adjust pH of watering and chelates.

• →**Fungi and bacteria**: sunken and wet spots (bacterial infections); necrosis with halo or pycnidia (anthracnose); rot in neck/root with foul odor. Management: sanitation + authorized fungicides + watering adjustment.

• →**Viruses (e.g., Cactus virus X)**: mosaics, rings, mottling that do not respond to treatments; there is no cure. Isolate or discard affected material to protect the rest.

Integrated Pest Management (IPM) for Trichocereus

1) Prevention and hygiene

• →**Quarantine** 3–4 weeks for any entry; inspections with a magnifying glass.

• →**Disinfection** of benches, tables, and tools; new substrate and clean pots.

• →**Balanced water and nutrition**; avoid excess N that softens tissues.

• →**Environment**: active ventilation in the greenhouse; avoid extreme dry heat microclimates (mites) or stagnant high RH (tarsonemids).

2) Monitoring and thresholds

• →**Weekly** reviews during the growing season; biweekly in dormancy.

• →Sticky traps: 1/10 m² (min.) and near doors/windows.

• →Photographic record and sheets by batch for timely decisions.

3) Biocontrol as the backbone

• →*Phytoseiulus persimilis*, *Neoseiulus californicus*, *Amblyseius andersoni*/*swirskii* for mites.

• →*Orius* and *Amblyseius* for thrips.

• →*Cryptolaemus*, *Anagyrus* for mealybugs.

• →Soil: *Stratiolaelaps* and entomopathogenic nematodes (*Steinernema feltiae*) as support.

4) Smart chemical interventions

• →Use **registered active ingredients** for ornamentals/cacti in your country; follow the label.

• →**IRAC rotation** to avoid resistance; 2–3 applications per cycle with appropriate intervals.

• →**Wetting agent** and 360° coverage of ribs and areoles; avoid applications in sun or high temperatures to minimize phytotoxicity.

• →Avoid oils and abamectin in **heat waves** and in full sun; conduct tests on a few plants before mass application.

Practical protocols according to symptoms

If you suspect root mealybug

• →Suspend fertilization and watering for 48 h; unpot carefully and **wash roots**.

• →Remove old substrate; prune dead roots; brief bath in soapy water.

• →Replant in new draining substrate; apply **drench** with authorized product or introduce *Stratiolaelaps* as support.

• →Control ants with bait and eliminate heavily infested pots if they are not valuable.

If there is “russeting” without webs

• →Check with a magnifying glass for *Brevipalpus*; install *A. swirskii* or *N. californicus* preventively.

• →Apply translaminar acaricide and repeat every 7–10 days; rotate mode of action.

• →Improve ventilation and reduce water stress.

If you observe silver and black dots

• →Confirm thrips with blue traps and tapping.

• →Release *Orius* + *A. swirskii* and alternate spinosad/ciantraniliprol according to the label.

• →Remove wilted flowers and clean benches.

If the apex deforms without cause

• →Evaluate eriophyids/tarsonemids; eliminate highly deformed tissue.

• →Targeted application of ovicidal/juvenile acaricide in the meristem; repeat.

• →Adjust climate: avoid high RH without air movement.

Monitoring Calendar (Northern Hemisphere; invert 6 months in Southern Hemisphere)

• →**Mar–Apr**: pest reactivation; place sticky traps; first release of beneficial mites.

• →**May–Aug**: peak of mites and thrips. Weekly inspections with a magnifying glass; gentle showers; rotate acaricides if thresholds are exceeded.

• →**Sep–Oct**: reduce N; prioritize K/Si to harden tissue; control root mealybug before dormancy.

• →**Nov–Feb**: minimal watering in cold; inspections every 3–4 weeks for root mealybug and scales on the neck.

Common Mistakes That Favor Invisible Pests

• →**Not using a magnifying glass**: you will delay diagnosis by weeks.

• →**Heavy watering with cold substrate**: predisposes to edema and rot that confuses diagnosis.

• →**Excess nitrogen**: soft tissues, more appealing.

• →**Applying oils in the sun**: risk of burns and corking.

• →**Not rotating modes of action**: resistance in mites/thrips.

Quick FAQ

• →**How do I distinguish mites from thrips without a microscope?** Tapping on cardstock: mites are small round dots that move slowly; thrips are elongated and run quickly. The silvery surface with black dots indicates thrips; rough “russeting” indicates mites, especially *Brevipalpus*.

• →**Is there a pest if I don’t see honeydew?** Yes; mites do not produce honeydew and cause severe damage without sooty mold.

• →**Can I use potassium soap?** Useful against airborne mealybugs and thrips nymphs as support. In Trichocereus, test on a small area first; do not apply in sunlight or heat.

• →**What should I do with a plant showing suspicious mosaic?** Isolate; if viral is confirmed, discard it to protect the rest. Disinfect tools.

• →**How often should I check?** Weekly during growth; monthly during dormancy. Always before and after movements/transplants.

Quick Reference Sheet: Symptoms → Main Suspected Issue

• →**Stagnation + yellowing + ants** → Root mealybug.

• →**Silvery + black dots** → Thrips.

• →**Progressive rough browning without webbing** → False mites (*Brevipalpus*).

• →**Fine mottling + possible webbing** → Red mite (*Tetranychus*).

• →**Deformed apex/witches' broom** → Eriophyids or broad mite.

TRICHOLAND: Technical Support and Scalable Solutions

At TRICHOLAND, we work with specific **Integrated Monitoring** protocols for *Trichocereus*, combining magnifying glass inspections, sticky traps, releases of natural enemies, and rotation plans of active substances compatible with ornamental cacti. We offer:

• →Advice on **quarantine and hygiene** for nurseries and collections.

• →Design of **biocontrol programs** (predatory mites, *Orius*, *Cryptolaemus*).

• →Recommendations for **substrates**, fertigation, and climate management that minimize pest risk.

• →Diagnostic checklists and **follow-up calendars** tailored to your climate.

If you need help confirming a diagnosis or developing an IPM plan for your collection or production, the technical team at TRICHOLAND is at your disposal.