The prickly pear cactus, a member of the Opuntia genus, is a hardy plant known for its flat, paddle-like stems. Although native to many arid regions, its rapid, invasive growth and sharp spines make it a significant agricultural and land management nuisance. Eradication is often sought to clear grazing land, reduce hazards to livestock, or reclaim dense infestations. Effective control requires specific, targeted physical or chemical methods that address the plant’s unique biological defenses.
Physical Removal Strategies
Physical removal is highly effective, especially for small, isolated plants or where chemical use is not desired. Destruction depends on removing the main root crown, which must be severed two to four inches below the soil surface using tools like a grubbing hoe or a sharp shovel.
Prickly pear pads are capable of rooting and growing into new plants through vegetative reproduction. Simply chopping the pads off the main stem is insufficient for eradication. All detached plant material, including the main trunk and fallen pads, must be collected and removed from the site to prevent re-infestation. For large, dense stands, mechanical equipment like a skid-loader with a rock rake attachment can be used to grub out the plants, but this is usually costly.
Chemical Eradication Methods
The primary challenge in killing prickly pear with herbicides lies in its thick, waxy outer layer, or cuticle, which prevents chemical absorption. This coating causes general-purpose weed killers to run off, failing to reach the plant’s internal transport system. Systemic herbicides are required, meaning the chemical must be absorbed and moved throughout the plant to kill the root system.
The most effective herbicides contain active ingredients like picloram, often combined with fluroxypyr, found in commercial products such as Surmount™ or MezaVue. Picloram is a potent synthetic plant hormone that causes fatal, unregulated growth. To overcome the waxy barrier, a non-ionic surfactant must be added to the mixture, helping the spray solution spread and penetrate the pad surface.
For smaller plants, a foliar spray application covering all pads until wet (but not dripping) is the recommended method. Larger, mature plants benefit from stem injection, where the herbicide is injected directly into the pads to bypass the protective cuticle. Prickly pear dies slowly even after successful application; visible effects may take six to eight months, and total mortality can require up to two or three years.
Safety and Post-Removal Management
Handling prickly pear requires robust personal protective equipment to guard against the large spines and the much smaller, hair-like barbs known as glochids. Thick, puncture-proof leather gloves and tongs are necessary when collecting the pads, as glochids are easily detached and can cause severe skin irritation. If glochids become embedded in the skin, a common remedy involves applying a layer of washable glue or tape to the area, allowing it to dry, and then peeling it off to extract the fine barbs.
Proper disposal of the removed plant material is necessary to prevent it from re-rooting. The pads should either be buried deeply, typically under 18 to 24 inches of soil, or completely removed from the site. Piling the material in a remote location is not recommended as the pads can re-root into a new, impenetrable mound. When chemical methods are used, following the herbicide label instructions precisely is paramount, as chemicals like picloram can persist in the soil and potentially affect desirable non-target plants nearby.