Explore Plants

Share

Ask Mr. Smarty Plants

Ask Mr. Smarty Plants is a free service provided by the staff and volunteers at the Lady Bird Johnson Wildflower Center.

Search Smarty Plants
    
 

Can't find the answer in our existing FAQs, submit a question to Mr. Smarty Plants.
Need help with plant identification, visit the plant identification page.

rate this answer
Not Yet Rated

Sunday - March 25, 2012

From: Austin, TX
Region: Southwest
Topic: Diseases and Disorders, Cacti and Succulents
Title: Black fungus on cholla cactus from Austin
Answered by: Barbara Medford

QUESTION:

How to get rid of black fungus on cholla cactus? Cut it off? And treat with what?

ANSWER:

Cylindropuntia imbricata (Tree cholla) is native to Texas but not, as this USDA Plant Profile map shows, native to Travis County. However, if you are willing to provide the proper environment, there is no reason why it should not flourish. Here is an article with numerous pictures from Southwest Colorado Wildflowers; no mention of fungus, however, so we will look a little further.

We think you'll find the comments on this plant in this Dave's Garden forum interesting, especially considering the weather conditions they can survive, but still no fungus cures. From the Sonoran Desert Digital Library, more information on the plant.

Finally, a website mentioning fungus: from Arizona Cooperative Extension Pests of Agave, Aloe, Cactus and Yucca. Scroll down to Page 6, where you will find "Fungal diseases of leaves and pads." On Page 7, we found a section on Insects which included this description of the Cactus Longhorn Beetle:

"This beetle attacks several species of cacti including prickly pear and cholla cactus (Cylindropuntia species), barrel cactus (Echinocactus and Ferocactus species), young saguaro cactus (Carnegiea gigantea), and others. The adult beetle is about 1 to 1¼ inches (2.5 - 3 cm) long, shiny black, and has distinctive white markings on the antennae. The antennae are often longer than the overall body length of the adult beetle. Damage to the plants is the result of feeding on the margins of prickly pear pads or terminal buds of other cacti (Fig. 18).

Cholla cacti are attacked by the beetle when the adults lay their eggs, hatch and the larvae burrow into the stems. Waste (frass) is pushed out the entry holes and forms a black crusty deposit on the canes. Larvae may burrow into plant roots and cause collapse and death of the plants.

Cactus longhorn beetle is controlled by hand picking the insects off infested plants. The beetles are most active and easier to detect and destroy in the early morning or late evening, especially after warm summer rains. Very spiny species are less likely to have damage from the beetle due to a natural defense by the spines. Chemical control is not recommended since the populations usually are not high and hand picking is effective."

This may or may not be the situation with your cholla, but the pictures throughout the article are excellent and you may well find your problem somewhere else in it.

From the Arizona Department of Agriculture, we found Bacterial Necrosis of Saguaro Cactus. This article states that the same condition has been noted in cholla cacti. It gives instructions on cutting out the rot and treatments for it. Again, since we are not plant pathologists and cannot see the cactus, you will have to be the judge of which treatment, if any, you wish to use.

 

From the Image Gallery

More Diseases and Disorders Questions

Wisteria with root rot in Flower Mound, TX
July 11, 2009 - I have a wisteria that is showing rot root from an exposed wound on the side of the base. Would like to save the tree. What can I do to fix the problem.
view the full question and answer

Peach tree problems in Long Island, NY
June 16, 2008 - This year my peachtree is bearing fruit for the first time. I live in Long Island NY. I notice a sap on the bark near the soil. Also some leaves are getting disease looking and some peaches are loo...
view the full question and answer

Problems with winecups in Taylor, TX
May 09, 2010 - I live in Taylor in Williamson County, Tx,. I have wine cups growing. They are lush and blooming, but I am now noticing what looks like spores forming under the leaves and the plants seem to be suffer...
view the full question and answer

Mice eating seeds put out for birds
June 02, 2008 - I love feeding the wild birds and put out seed in our backyard. Now, I have a family of mice eating the seed and they are living in the trunk of our elm tree! How can I get rid of them without killi...
view the full question and answer

Problems with giant coneflower in Richardson TX
June 05, 2010 - Dear Mr Smarty Plants- I have had a giant coneflower in my garden for 2 years now. This year it came up like it always had..got lots of leaves and then withered..turned brown and died. It got plent...
view the full question and answer

Smarty Plants's Facebook profile Support the Wildflower Center by Donating Online or Becoming a Member today.

Mr. Smarty Plants wants you to be his Facebook friend. Click the Facebook icon to add yourself to Mr. Smarty Plants list of friends.