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.
2011–2017 California drought
By February 1, 2014, Felicia Marcus, the chairwoman of the State Water Resources Control Board, claimed the 2014 drought "is the most serious drought we've faced in modern times." Marcus argues that California needs to "conserve what little we have to use later in the year, or even in future years." A 16-year study of how precipitation affects groundwater-dependent vegetation was conducted and the results showed that the alkali meadow vegetation plant community is groundwater dependent and that this characteristic buffers the system from the effects of drought. This means that certain plants are actually able to help prevent droughts, but can only do so if groundwater is maintained at a certain level. One of the reasons that the study was conducted was to ascertain whether the Owens Valley region of California could handle any practiced or proposed groundwater extraction.