Corynespora cassiicola

[1] The fungus is known as a pathogen of many agricultural crop plants, especially cowpea, cucumber, papaya, rubber, soybean, and tomato.

[2] The disease is identified by leaf damage taking the form of target-shaped spots with light centres and dark margins, as well as pits on the fruit.

[3] The fungus also causes a disease on the cultivated rubber tree Hevea brasiliensis called corynespora leaf fall (CLF).

[4] It is one of the most economically significant fungal pathogens of rubber trees in Asia and Africa, causing "fishbone"- or "railway track"-shaped lesions on the leaves.

[5] In regards to detection of Corynespora cassiicola, it is useful to inspect the plant's bottom leaves while looking for ring-patterned spots that can be up to 10 mm in diameter.

If the pathogen is discovered after harvesting the host, management includes burning the infected crop in the attempt to rid the disease from the environment.

Furthermore, practicing plant rotation and waiting three years before replanting the host on the same land can be beneficial for pathogen prevention.

Although Corynespora cassiicola has been reportedly located in a wide distribution throughout the world, the conditions in which this pathogen best spreads and develops are found in the tropics and subtropics.

In other words, the leaf wetness is likely a major environmental factor driving the disease for this fungal pathogen.

Images of the symptoms in this opportune environment have been provided by professors of plant pathology from Florida, Dr. Ken Pernezny and Dr. Gary Vallad.

These illustrations are important to note because they depict the symptoms of Corynespora cassiicola on a tomato plant that is developing in its favorable environment.

[13] The photograph by Dr. Ken Pernezny illustrates the foliar damage of Corynespora cassiicola and the reduced yield of tomato plants in a Florida field.

[13] This broad host range adds danger in the fact that this economic loss does not just apply to one specific crop.

[14] Because it also infects many plants that are considered noxious weeds, the fungus has been proposed for use as a bioherbicide and an agent of biological pest control.

Corynespora cassiicola ring-spots symptoms on the leaves of tomato plants. Photograph by Dr. Ken Pernezny from University of Florida.
Photograph by Gary Vallad, Assistant Professor of Plant Pathology at University of Florida, Gulf Coast REC.
Photograph by Dr. Ken Pernezny from University of Florida.
Successful proof of Koch's Postulates conducted by Abraham Fulmer in 2011at the University of Georgia. This experiment proves that the disease Tomato ring spot disease is caused by Corynespora cassiicola.