Pseudocercospora ixoricola Causing Leaf Spots on Ixora coccinea in Brazil

Area of Science:

• Plant Pathology
• Mycology
• Botany

Background:

• Ixora coccinea (jungle geranium) is a popular ornamental shrub in Brazil, introduced from Eastern India.
• Recent observations revealed significant leaf spot symptoms on I. coccinea foliage, causing aesthetic damage and defoliation.

Purpose of the Study:

• To identify and characterize the causal agent of the observed leaf spot disease on Ixora coccinea in Brazil.
• To confirm the pathogenicity of the isolated fungus and determine its taxonomic placement.

Main Methods:

• Fungal isolation from diseased leaf tissues and pure culture establishment on V8 juice agar.
• Microscopic examination of fungal structures, including conidiophores and conidia, for morphological characterization.
• Pathogenicity tests conducted by inoculating healthy I. coccinea plants with the isolated fungus.

Main Results:

• A fungus, morphologically consistent with Pseudocercospora ixoricola, was consistently isolated from diseased I. coccinea.
• Inoculation studies confirmed the fungus as the causative agent of leaf spot symptoms, including lesions and premature abscission.
• The identified fungus exhibited distinct morphological characteristics separating it from related Pseudocercospora species.

Conclusions:

• This study reports the first occurrence of Pseudocercospora ixoricola causing leaf spot disease on Ixora coccinea in South America.
• The findings highlight the emergence of a new plant pathogen impacting ornamental Ixora cultivation in Brazil.
• Further research may be needed to understand the epidemiology and management of this disease in the region.