Cleistocactus strausii
As a houseplant, the Silver Torch cactus is an easy to take care of so long as over-watering is avoided. To naturally simulate the porous effects of the sand in its native habitat, it's important to ensure that excess water will not pool in the soil, causing the roots to become water logged.
This plant’s native habitat does not have winter, but when temperatures drop to the low twenties, it can exhibit signs of tip frost. 
The Silver Torch cactus is most susceptible to 
mealybugs 
and spider mite.
Pseudomonas cichorii
To best prevent the spread of "pseudomonas cichorii" the first intervention is to regulate the free water and watering system of leaves. Overhead sprinklers and hose watering should be replaced with soil irrigation. Soil irrigation is useful because it prevents excess water accumulation on plant surfaces by watering the plant from the root system. Soil irrigation also limits the ability of the seed structures to grow and infect leaf surfaces. A second intervention is watering earlier in the day. Watering earlier in the day gives the leaves more time during the day to dry. A third intervention, is to minimize leaf splashing. This lessens the chance that the infected water will spread to another host. Sanitation is also important. Workers and those handling the infected leaves should wash their hands and keep infected plant material from uninfected areas. These infected cuttings and seedlings should not be planted or kept near uninfected fields as the pathogen is able to survive on the host's seeds. Chemical control with appropriately labeled copper or other bactericidal products can be used to help manage the disease but is not always successful in preventing disease spread when conditions are wet.