Cactus
Fungi, bacteria and viruses attack cacti, the first two particularly when plants are over-watered. Fusarium rot can gain entry through a wound and cause rotting accompanied by red-violet mold. ""Helminosporium" rot" is caused by "Bipolaris cactivora" ( "Helminosporium cactivorum"); "Phytophthora" species also cause similar rotting in cacti. Fungicides may be of limited value in combating these diseases. Several viruses have been found in cacti, including cactus virus X. These appear to cause only limited visible symptoms, such as chlorotic (pale green) spots and mosaic effects (streaks and patches of paler color). However, in an "Agave" species, cactus virus X has been shown to reduce growth, particularly when the roots are dry. There are no treatments for virus diseases.
Echinopsis pachanoi
In most countries it is legal to cultivate the San Pedro cactus, but in countries where possession of mescaline and related compounds is illegal and highly penalized, cultivation for the purposes of consumption is most likely illegal and also highly penalized. This is the case in the United States, Australia, Canada, Sweden, Germany, and New Zealand, where it is currently legal to cultivate the San Pedro cactus for gardening and ornamental purposes, but not for consumption.