En EspaÑol

Q. Who is Mr. Smarty Plants?

A: There are those who suspect Wildflower Center volunteers are the culpable and capable culprits. Yet, others think staff members play some, albeit small, role. You can torture us with your plant questions, but we will never reveal the Green Guru's secret identity.

Help us grow by giving to the Plant Database Fund or by becoming a member

Did you know you can access the Native Plant Information Network with your web-enabled smartphone?

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
    
 
See a list of all Smarty Plants questions
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

Friday - September 28, 2012

From: Austin, TX
Region: Southwest
Topic: Diseases and Disorders, Cacti and Succulents
Title: Film growing on prickly pear from Austin
Answered by: Barbara Medford

QUESTION:

We've just xeriscaped our front & back yards. Two of the spineless prickly pear cacti have a beige film growing on the paddles. The film is now moving further up the cactus, and one of the upper paddles fell off yesterday. What do I need to do to prevent the film from growing, and to improve the condition of the plants?

ANSWER:

From CactiCare.com here is an article on Pests and Diseases of Opuntia, including Opuntia ellisiana (Spineless prickly pear). We are not clear on what the film is on your cacti pads but scroll down the page and look first at Cochineal Insects and then at Thrips.

From a previous Mr. Smarty Plants answer:

The Plant Pathology Lab of Texas A&M has released a list of Opuntia diseases. Here are some extracts from that article:

Cactus Anthracnose (fungus - Colletotrichum (Gleosporium) spp.): This disease affects several kinds of cacti, Cereus, Echinocactus, Mammillaria, and particularly Opuntia (prickly pear). Infection results in a rather moist light brown rot which shows many light pink pustules on the surface. Spots are small at first, later enlarge and become covered by the small spore-producing pustules. Large areas may be affected, sometimes destroying entire plants. No satisfactory control is available, other than removing and destroying diseased cladodes as soon as noticed. In the greenhouse, soil from infected plants should be removed and benches disinfected. Spraying with a copper fungicide may help in checking the disease.

Scorch or Sunscald (fungus - Hendersonia opuntiae): This disease is common and serious on prickly pear cactus (Opuntia). Spots at first are distinctly zoned, later enlarging until entire cladodes turn a reddish-brown and finally die. The center of the disease area is grayish-brown and cracked. Other fungi may also be present in the diseased area. No practical control has been developed.

Scab (physiological): Particularly common on prickly pear cactus. Rusty colored, corky areas appear on the stems. Scab is thought to be a form of edema, resulting from overwatering and poor ventilation. Increase light and decrease humidity for control.

Stem Rot of Cacti (fungus - Drechslera cactivorum): Basal or top rot of seedling cacti that turns cactus into a shrunken mummy covered with brown spores. First symptoms are yellow spots. It can completely rot a plant in four days. The fungicide Captan should give some control.

Doesn't sound good, does it? We searched for pictures of the various diseases on a prickly pear, so you could compare them, but didn't find any. In fact, virtually every search phrase we used returned us to the article from Texas A&M that we have already referenced. On a couple of discussion websites, we found that Opuntia is considered by many an invasive weed, and no one seemed too interested in curing its diseases.

Summary: See each disease for suggestions for treatment, usually, cutting out the diseased portion and disposing of it in a way to prevent the disease being passed to others. Scab may be caused by watering the cactus, having it in too much shade and/or poor circulation. So, you could move it to a better location-now there's a challenge!

 

From the Image Gallery


Spineless prickly pear
Opuntia ellisiana

Spineless prickly pear
Opuntia ellisiana

Spineless prickly pear
Opuntia ellisiana

More Cacti and Succulents Questions

How to Control White Fungus on Prickly Pear Cactus?
July 04, 2013 - Is there any kind of spray for our prickly pear that will help with the white fungus that has appeared on it?
view the full question and answer

Loss of agaves to freezing weather in Austin
March 04, 2011 - Dear Mr. Smarty Plants: I live in Austin and lost all my agaves in the subfreezing weather this winter. Around town, I've noticed some agaves that seemed to tolerate the cold just fine and other tha...
view the full question and answer

Dead leaves on yucca in Georgetown TX
October 18, 2010 - We have 2 6ft and 3 smaller soft leaf yuccas out back in a kidney shaped area with a wax myrtle and a mountain laurel. The yuccas have done great but now two of them have a large number of dead leaves...
view the full question and answer

Plants for 100 gal. pot by pool from Ft. Worth TX
June 23, 2012 - What North Texas evergreen — or combination of evergreen plants, bushes or trees — could thrive in a huge, 100-gallon clay pot (immovable!) that is situated in full sun year round in an exposed area n...
view the full question and answer

Identification of green succulent plant with red tubular flowers
October 08, 2007 - Hi there, i have this plant which is green,leaves are succulent, and these red tubular little flowers about an inch long grow rampantly all summer. i wanna know what it is called as i take cuttings a...
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.
E-NEWSLETTER | BECOME A MEMBER | DONATE NOW | MEDIA | SITEMAP
© 2014 Lady Bird Johnson Wildflower Center