Witch's Broom

Witch's Broom is a pathological condition and growth symptom in cacti, characterized by highly abnormal, hyper-clustered growth. It affects various species, including *Trichocereus* and *Lophophora*. * Rib Count: In affected areas, distinct ribs are typically absent or highly reduced due to the extreme density of the stacking growth points. * Spines: Spines on the clustered pups are often miniature, dense, and can range from light yellow to brown, though they are frequently obscured by excessive areolar wool. * Epidermis: The epidermis remains light to dark green in early onset but turns yellow to red as the disease progresses and growth outpaces nutrient availability. In heavily afflicted areas the epidermis is heavily crowded by the rapid proliferation of new shoots. * Areoles: Areoles in the affected zones often produce an abundance of dense white fluff or wool. * Foolproof tell: pups on pups on pups. Pups coming out of every areole of other recent pups.

* Pathological Origin: The most severe, infectious form is caused by a Mycoplasma-Like Organism (MLO), a type of phytoplasma. This pathogen is highly contagious and spreads rapidly through collections. * Pest-Induced Origin: The phytoplasma infection can spread from insects feeding on afflicted plant areas, then feeding on other healthy plants.

* This condition is easily confused with natural monstrose, crested, or caespitose growth forms (such as *Lophophora williamsii f. caespitosa*). * Non-infectious “brooming” can be triggered by physical damage to the meristem. Sucking pests like mealybugs, mites, or caterpillars can damage the growing tip, causing it to terminate and throw a dense cluster of lateral pups. * Genetic & Environmental Origin: Certain genetic lines, particularly crosses involving the cultivar “Olivia” (such as Olivia x Jess), are highly prone to throwing funky, clustered growth that mimics Witch's Broom. This is often a systemic response to environmental inputs like nutrients and lighting rather than a pathogen.

Proper management of suspected Witch's Broom is critical to protecting a collection: * Quarantine: Immediately isolate any suspect plant. Keeping it quarantined at a significant distance (e.g., 200 yards) from the main collection is highly recommended while monitoring the growth. * Culling: If infectious phytoplasmic (MLO) Witch's Broom is suspected, the safest course of action is to burn the plant, pot and all, to prevent rapid spread. * Surgery: For valuable specimens showing localized or pest-induced damage, growers have successfully excised the affected parts. Use a knife sterilized with isopropyl alcohol to cut away the clustered growth. Dust the wounds with sulfur. If treating the roots, cut off feeder roots, dip the main root in a diluted hydrogen peroxide solution, and repot in fresh, high-quality, well-draining cactus soil. * Pest Management: Treat the plant for mealybugs and other pests, if present. This should help prevent spread and reintroduction.

Analysis of the discussion. The community discussion centers on distinguishing true infectious Witch's Broom from benign look-alikes. Experienced growers emphasize that “Witch's Broom” is often used as a catch-all term for a set of symptoms rather than a single disease. While the phytoplasmic (MLO) variant is highly contagious and destructive, many cases of “brooming” are actually caused by localized pest damage (such as mealybugs or caterpillars terminating the meristem) or genetic mutations.

In particular, crosses involving the cultivar “Olivia” are noted for naturally producing funky, highly clustered growth points that can easily be mistaken for the disease. Topic experts advise adjusting environmental factors like nutrients and lighting before panicking, as these genetic lines frequently exhibit systemic responses to cultivation inputs.

* Gee Bee (10/10): Recognized as a premier topic authority on Trichocereus genetics. Their expertise on “Olivia” crosses and environmental growth triggers overrides general community speculation. * Kelly Beth Costello (8/10): Provided direct scientific literature citations regarding Mycoplasma-Like Organisms (MLO) and offered clear, actionable biosecurity advice. * Sam Payne (8/10): Provided a highly detailed, accurate botanical breakdown distinguishing between pest-induced meristem termination and contagious phytoplasmic infections. * Thomas Lauritzen (7/10) & Matt Olson (7/10): Offered consistent, detailed diagnostic criteria regarding clustering density, hormonal shifts, and genetic mutations. * ScrapGoat Benjamin (6/10) & Cody Hinds (6/10): Provided solid, practical cultivation advice and accurate conceptual definitions of the symptom, backed by years of observation.