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First Report of Diaporthe tulliensis Causing Necrotic Spots and Leaf Blight on Rambutan in Puerto Rico
Luz M Serrato-Diaz1, Ashley Aviles-Noriega2, Lydia I Rivera-Vargas3
1USDA-ARS Tropical Agriculture Research Station, 57769, 2200 P.A. Campos Avenue Ste. 201, Mayaguez, Puerto Rico, 00680-5470; luz.serrato@usda.gov.
Plant Disease
|July 31, 2023
Summary
A new fungal pathogen, Diaporthe tulliensis, has been identified causing significant leaf blight and necrotic spots on rambutan (Nepehelium lappaceum) crops in Puerto Rico. This marks the first report of this disease on rambutan, necessitating effective management strategies.
Area of Science:
- Plant Pathology
- Mycology
- Tropical Agriculture
Background:
- Rambutan (Nepehelium lappaceum) is a tropical fruit susceptible to various pathogens, though leaf diseases are less documented.
- A disease survey was conducted in Puerto Rico from 2015-2021 to identify causal agents of leaf necrosis and blight in rambutan.
Purpose of the Study:
- To identify and characterize the fungal pathogen responsible for necrotic spots and leaf blight in rambutan.
- To confirm the pathogenicity of the isolated fungus on rambutan seedlings.
Main Methods:
- Fungal isolation from diseased rambutan leaves, followed by morphological and molecular identification using ITS, BT, and TEF1-α gene regions.
- DNA sequencing and BLASTN analysis were performed to compare isolates with known Diaporthe species.
- Pathogenicity tests were conducted on rambutan seedlings to fulfill Koch's postulates.
Main Results:
- Two isolates, identified as Diaporthe tulliensis, were consistently isolated from diseased rambutan leaves.
- Morphological characteristics and molecular data (ITS, BT, TEF1-α sequences) confirmed the identity of the isolates.
- Inoculation of rambutan seedlings with D. tulliensis resulted in typical necrotic spots and leaf blight symptoms, confirming pathogenicity.
Conclusions:
- Diaporthe tulliensis is identified as the causal agent of necrotic spots and leaf blight in rambutan in Puerto Rico, representing a novel host-pathogen interaction.
- This finding underscores the importance of disease monitoring and the development of management strategies for this emerging threat to rambutan cultivation worldwide.
