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.
Echinomastus mariposensis
Threats to this rare species have included mercury mining, petroleum exploration activities, off-road vehicles, and grazing. The worst threat has been poaching by cactus collectors. The collectors employed professional diggers to go into the habitat and retrieve this and other species of cacti, which were stockpiled, shipped away for sale, and sometimes discarded or wasted. The type locality of the cactus has been scoured for specimens and few are found there anymore. Plants in Big Bend National Park occur on rugged terrain and have generally been safe from collectors. In 1983 the cactus was placed on Appendix 1 of CITES in an effort to protect it from harvesting.