First Report of Lasiodiplodia hormozganensis Causing Fruit Rot of Eggplant in Haiti

Eggplant (Solanum melongena) is a major component of the vegetable crop produced for domestic consumption within Haiti, estimated at 851 metric tons in 2017 (FAO 2019). In a preliminary study in June 2018, eggplant fruits were observed with circular, tan, water-soaked lesions that extended to the entire fruit, which became spongy and mummified. Incidence of disease in two plots at the Centre Rural de Développement Durable de Bas-Boen, Croix-des-Bouquets, Haiti, was estimated at 20%. Two isolates, G18-1373 and G18-1374, were obtained from the margins of actively expanding lesions and cultured on water agar plates supplemented with sterile pine needles. Conidia were produced in pycnidia after 14 days at 25°C and were cylindrical to spherical in shape, melanized, striated, with equatorially positioned septa and measured 18.7 ± 2.8 μm long and 11.2 ± 1.3 μm wide (n = 400 per isolate), placing the isolates morphologically in Lasiodiplodia. Pathogenicity testing of both isolates was performed on two eggplant fruits for each of the two isolates, plus a negative control fruit. Prior to inoculation, the fruits were surface sterilized for 1 min in dilute bleach (0.6% sodium hypochlorite solution) and then rinsed twice with sterile tap water. Inoculation was performed by excising a 5-mm-diameter tissue core out of the fruit, which was replaced with a 5-mm-diameter acidified potato dextrose agar (APDA) plug containing actively growing hyphal tips. Negative controls were inoculated solely with a 5-mm core of APDA. The wounds were wrapped with Parafilm following inoculation, and the fruits were placed in a humid chamber kept at 25°C. Three days postinoculation, the fruits were evaluated for disease development. The inoculation experiment was repeated twice. The control fruits remained asymptomatic. Fungi were reisolated from the symptomatic plants and compared with the original strains, matching morphological identity to the original isolates. However, morphology is not a suitable characteristic to distinguish species in Lasiodiplodia, so regions of the internal transcribed spacer rDNA (White et al. 1990), translation elongation factor 1-α (Machado et al. 2014), and β-tubulin (Glass and Donaldson 1995) were sequenced for both isolates, resulting in GenBank accession numbers MK040609, MK040610, MK040617, MK040618, MK040619, and MK040620, respectively. A combined phylogenetic tree obtained by maximum likelihood using MEGA (https://megasoftware.net) and checked for concatenation allowance using PAUP (https://paup.phylosolutions.com) grouped the isolates within the Lasiodiplodia hormozganensis clade. The genus Lasiodiplodia contains several important phytopathogenic species on a wide range of hosts (Alves et al. 2008), including closely related L. theobromae, reported to cause fruit spot on eggplant (Vieira et al. 2018; Woodward et al. 2005). To our knowledge, this is the first report of L. hormozganensis causing fruit rot in eggplant. Chemical disease management is limited in Haiti; therefore, investigation of the host range and disease incidence in eggplant growing areas is necessary to determine if removal of inoculum is a viable strategy.