Bacterial Infection

Bacterial infection in Trichocereus is characterized by fluid-filled epidermal lesions and the discharge of a dark, viscous “black goo.” The epidermis displays off-color, “dirty green” watery blobs that appear as though liquid is trapped directly beneath the outer skin layer. These affected areas often look blistered and can be easily peeled off. Over time, these lesions typically dry out, contract, and form rough, tan-to-brown scars along the ribs of the cactus.

While bacterial pathogens are native to all environments where cacti are grown, the specific diagnostic criteria separating bacterial infections from fungal or chemical damage in the Trichocereus community were heavily popularized by the grower Gee Bee. The condition is frequently misdiagnosed as fungal “humidity spots” or chemical burns.

* Active Treatment: Apply a biological bactericide containing *Bacillus amyloliquefaciens* strain F727 (such as Arber Bio Fungicide or Southern AG formulations) as a foliar spray and soil drench. Alternatively, apply an oxidizer spray starting at 150 ppm up to 200 ppm. * Passive Management: In high-humidity environments (such as the Gulf Coast, with 80-90% humidity), many growers recommend leaving the infection to resolve naturally. The cactus will typically wall off the infection and scar over without long-term damage to growth. * Prevention: Avoid letting plants become root-bound, as the resulting stress compromises the plant's immune system and makes it susceptible to opportunistic bacterial outbreaks.