Types

• A fungal infection called helminthosporium infects the small cylindrical variety of cactus called echinocereus, while a soil-borne pathogen called pythium damages barrel cacti. Prickly pears are affected by phyllostica pad spot. Various types of cacti are affected by cactus anthracnose, which is caused by the colletotrichum fungus.
  
  

Effects

• Helminthosporium infections are characterized by soggy, dark, sunken areas of rot on the upper part of the plant. The plant also rots from the inside. Pythium rot causes a similar type of rot deep inside barrel cacti; the infection attacks wounded, incorrectly planted and overwatered plants. Cacti with phyllosticta pad spot develop small black spots, while cactus anthracnose creates light brown spots with small pinkish pustules on the outer surface of the plant.
  
  

Prevention/Solution

• Prevent pythium rot with mefanoxam treatments and proper cultivation practices. Remove plants that are affected with helminthosporium, phyllosticta and anthracnose so that they do not infect surrounding succulents.