Anthracnose on Cactus
Anthracnose is caused by a fungus (Colletotrichum spp.) and afflicts many plant species. Anthracnose fungus in cacti affects several types of cacti:
Cereus Echinocactus Mammillaria Opuntia (prickly pear)
The first signs of infection are dark, water soaked lesions on stems, leaves, or fruit. Soon, the interior of the lesions becomes covered with a pink, jelly-like mass of spores. Within a few days of infection, the pink, gelatinous spores enlarge and eventually the plant tissue hardens and dries out. Agaves are also often afflicted, most often in the fall when the weather is wet. This fungal disease in cacti overwinters in and on seeds, soil and garden detritus. Wet, cool weather encourages development. Moist, warm temperatures of between 75 and 85 F. (24 and 29 C.) cause an increase in the growth of spores that are then spread via rain, wind, insects, and gardening tools.
Treating Anthracnose in Cactus
Once the plant is afflicted with anthracnose, there is no optimal cacti anthracnose control. Obviously, infected leaves (cladodes) can be removed but may not stop the progression of the infection. Use a knife that is disinfected before each cut. Disinfect by dipping the knife in one part bleach to four parts of water. In greenhouses, soil should be removed from areas of infected plants. All tools and pots need to be thoroughly disinfected. An application of copper fungicide, Maneb, Benomyl, or Dithane may aid in destroying any remaining fungi. Be sure to completely destroy any infected parts or complete plants so they do not infect other areas. Practice good garden sanitation by removing any rotting plant debris immediately. Water plants at the base to avoid splashing and spreading spores. Keep tools disinfected.
