How does a cactus get sick?

Answer 1

A cactus gets sick mainly because of inappropriate levels of heat, light, moisture, and vegetative competition. The key disabling factors are the amount of moisture and the degree of coldness. A cactus plant's entire internal structure is geared towards wringing precious moisture out of an extreme environment. It isn't geared towards dealing with chilled, water logged body parts. For example, overwatering blackens, rots, and kills cactus tissue. Depending upon the extent of the damage, the entire plant may sicken and die.

A cactus also gets sick because of predators. The predators may be linked with the preceding problems. Examples are moisture loving bacteria, fungi, and microbes.

Or the predators may be in search of scarce fleshy, juicy food in an extreme environment. The cactus plant generally can handle predation by birds and small mammals that turn around and disperse cactus seeds over a wider area than where the plant is located. But it may not be able to handle predation by birds in search of nesting cavities or by bugs in search of juicy shoots and roots.