Flat-top decay syndrome of the giant cardon cactus (Pachycereus pringlei) of the Baja California Peninsula, Mexico

Discovered by
Yoav Bashan, Gerardo Toledo* and Luz E. de-Bashan

Environmental Microbiology Group, Northwestern Center for Biological Research
(CIBNOR), La Paz, B.C.S., Mexico

*Present address: Synthetic Genomics, San Diego, California, USA

Dedication: This website is dedicated to the memory of the late Mexican researcher Dr. Gina Holguin and the late editor of CIBNOR, Dr. Roy Bowers who participated in the discovery.

New research development in 2011

Flat-top decay of cardon cactus

Flat-top decay of cardon cactus

Normal giant cardon

The spectacular giant columnar cardon cactus (Pachycereus pringlei) appears to have an ailment(s) that is destroying many plants. The causal agent(s), whether biotic or abiotic, has not been determined.

Two forms of symptoms have been recorded. The first is a circumferencial band of decay on a branch that leads to death of the growing tip. In this case, the dead portion detaches and forms a flat top on the living part. Progressive degeneration and death of the entire plant follows.

The second form is an initial circumferential crack on the branch without decay. Later, the green branch above the crack detaches, creating the characteristic flat top.

A third type of degeneration, called fatal bleaching, has also been observed. The time period between initiation of symptoms and death of the plant is unknown. It primarily affects mature, 100-year-old plants, but relatively young plants are also affected. During 31 field surveys covering the entire state of Baja California Sur in Mexico we found four major and three smaller centers of flat-top decay. We believe that flat-top decay syndrome of the cardon is common and widespread. Whether this presents a danger to the existence of this magnificent and endemic species of cactus is not known.

This website contains description of the phenomenon, map showing locations of outbreak in the State of Baja California Sur, Mexico, five PowerPoint presentations of the phenomenon (presentation 1, Initial symptoms of decay; presentation 2, Advanced symptoms of decay; presentation 3, Typical symptoms of decay; presentation 4, Other symptoms of flat top decay and gray decay; and presentation 5, Why the affected cacti disappear) and the original scientific and popular reports (PDF file) in English (1 and 2) and Spanish (1 and 2).

Additional information about flat-top decay

Additional general reading about giant cardon (various languages)

A call for research students : Although this phenomenon was discovered over a decade ago, so far no student has wished to make it the topic of his/her thesis. We welcome any initiative.

For more information, contact:

Prof. Yoav Bashan


Page designed by Noga Bashan

Version: December 2010

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