Prickly Pear Cactus Problems

Wild Cactus Problems

• Prickly pear cactus has few predators, thanks to its prickles. But few insects are concerned with prickles, and there are some insects that can withstand the harsh brushland or desert environment that prickly pear cactus is native to. One species of insects that is particularly problematic for prickly pears is the Chelinidea species. These insects and their larvae feed in colonies on the young leaves and joints, leaving yellow spots that coalesce over time. The injury leaves way for fungal infection that will kill off the cactus if the infestation is bad enough. Cactus longhorn beetles (Moneilema gigas) feed on the margins as adults and cause cosmetic damage, but may kill the plant if the larvae burrow into the roots.

Home Garden Cactus Problems

• Prickly pear cactus raised at home are more vulnerable to mealy bug and Cochineal scale (Dactylopius coccus) infestations. These are slow-moving, sucking insects that form white, cottony colonies on the surface of the leaves. Prickly pear cactus can usually tolerate low levels of feeding insects when grown in hot sun and soil that dries out completely between watering. But shady areas weaken the skin, and over-watering makes it more succulent, and lack of circulation protects the insects, not the cactus.

Problems for Ranchers

• Prickly pear cactus spreads slowly but constantly. Efforts to root it out or mow it over only spread the cactus, since even small portions of the leaf blade will root given time. Prickly pear cactus is not edible to livestock, and the prickles are dangerous to the body and mouths of feeding animals. If it covers enough of the grassland, it can make the area useless for livestock. This happened in many areas of Australia, where prickly pear cactus was introduced and thrived without its natural insect and fungal predators.

Considerations

• Prickly pear cactus have edible leaves and produce ornamental flowers prized by arid-climate gardeners. In some areas, ranchers welcome prickly pear cactus producers to take as many of the plants off the ranch land as possible to help keep it from spreading. But in most cases, natural predators such as the cactus longhorn beetle and the Chelinidea insects are released in the rangelands as a biological control of prickly pear cactus.