First Report of Fruit Basal Rot by Ceratocystis paradoxa on Coconut in Taiwan

Abstract

Since 2005, coconut fruits (Cocos nucifera L.) harvested from trees in southern Taiwan have shown symptoms of a fruit rot disease. The disease occurs only on harvested coconut fruits and is more serious during warmer seasons. Principal symptoms are blackening of the exocarps, mesocarps, and then the endocarps of coconut fruits from pedicel end or wounds on fruits. A fungus was consistently recovered from diseased fruits. Colonies on potato dextrose agar (PDA) were white, becoming black 1 to 2 days later, with a strong fruity aroma. The fungus produced two asexual spores, including phialospore-type conidia, which were hyaline to mid brown, cylindrical to somewhat oval and thick walled when mature, 8.5 to 16.0 × 4.7 to 6.7 μm, released from phialides measuring 80.0 to 155.0 × 5.0 to 7.8 μm, and chlamydospores, which were oval, black, 13.4 to 25.0 × 8.9 to 12.5 μm, and formed in short chains from specialized hyphal tips. Perithecia were produced after 2 months by mating isolates on coconut exocarp placed on PDA. Perithecia were brown, globose, 280 μm in diameter, with a 1,100-μm long neck. Ascospores generally were ellipsoid, but some were unequally bent, 12 × 3 μm. The temperature for hyphal growth of this fungus was 25 to 30°C, with a growth rate of 3.3 cm per day. It did not grow at temperatures lower than 10°C or higher than 35°C. On the basis of these characteristics, this fungus was identified as Ceratocystis paradoxa (Dade) C. Moreau (anamorph Thielaviopsis paradoxa (de Seynes) Höhn) (1). The internal transcribed spacer (ITS) region of mycelial DNA of two isolates was amplified with ITS5 and ITS4 primers and the PCR products were sequenced (GenBank Accession Nos. GU358207 and GU358206). BLAST analysis of both sequences showed 99% sequence similarity with C. paradoxa strain WIN(M) 925 (Accession No. DQ318203). Two of the isolates (BCRC 34425 and BCRC 34426) were deposited in the Bioresource Collection and Research Center, Hsinchu, Taiwan. Twenty-four detached healthy coconut fruits were inoculated by placing spore suspensions (1 × 105 spores/ml) of eight wild type isolates onto wounds created by removing the calyx. Symptoms similar to those observed in the field developed on inoculated fruits after incubating at room temperature for 10 days, but did not develop on six fruits that were wounded but not inoculated. The same pathogen was reisolated from the inoculated fruits but not the control fruits. C. paradoxa has been reported as causing disease of coconut fruits in Brazil (2), but to our knowledge, this is the first report of the disease in Taiwan. References: (1) G. Morgan-Jones. No. 143 in: CMI Descriptions of Pathogenic Fungi and Bacteria. Commonwealth Mycological Institute, Surrey, England, 1967. (2) V. Rossetti. “Crostas Pretas” das folhas e “Podridão Basal” dos frutos de coqueiro. O Biológico 21:54, 1955.

First report on black spot disease of Phyllanthus emblica L. fruits caused by Thielaviopsis paradoxa in Bangladesh

“…At 15°C temperature, the mycelial growth was inhibited extremely, maximum mycelia growth was recorded at 35°C. Present results are in conformity with the findings of Tzeng and Sun (2010), which cited that the optimum temperature for hyphal growth of Thielaviopsis paradoxa was found at 25 to 30°C.This fungus did not grow at temperatures lower than 10°C or higher than 35°C. Yadahalli et al (2007) reported the maximum vegetative growth of Thielaviopsis paradoxa, causing sett rot of sugarcane, at temperature of 25-30°C.…”

Notes on Ceratocystis paradoxa causing internal post-harvest rot disease on immature coconut in Brazil

“…This species was also reported causing post-harvest diseases in banana, carambola, guava and pineapple (Reyes et al, 1998;Junqueira et al, 2001;Ploetz, 2003). This pathogen causes stem bleeding (Warwick & Passos, 2009;Freire & Martins, 2010) and fruit basal rot of the coconut at field conditions (Rossetti, 1955;Camargo & GimenesFernandes, 1997;Tzeng & Sun, 2009;Tzeng et al, 2010) and external post-harvest disease on coconut (Tzeng & Sun, 2009;Tzeng et al, 2010). Thus, this is the first report of postharvest internal rot disease on immature coconut caused by C. paradoxa.…”