First Report of Pestalotiopsis clavispora Causing Leaf Spot of Carya illinoensis in Brazil

Abstract

Conspicuous leaf spots in combination with fruit spots were observed for the first time in April and May 2010 on a 30-ha pecan [Carya illinoensis (Wangenh.) K. Koch] orchard in the state of Rio Grande do Sul, Brazil. Initially, tiny grey spots were observed on leaves and, over time, the spots expanded to become gray to light brown circles surrounded by a dark brown border, followed by leaves falling. Eventually, fruits were also attacked, with typical symptoms beginning with tiny water soaked spots which then became necrotic. The disease was also observed in pecan nursery and field seedlings. Isolation of the pathogen from symptomatic leaves and morphological identification by conidia characters (number of cells, color, hyaline terminal cells, number of appendages) revealed Pestalotiopsis sp. (2) as the causal agent of the disease. Conidia constituted of transverse septa with four dark intermediate sections and two hyaline terminal sections. One of the terminal sections presented two or three apical appendages. Conidia averaged 6.88 μm wide × 31.00 μm long, not considering the apical appendages. Primers ITS 1 and ITS 4 were used to amplify the internal transcribes spacer ITS 1-5.8S-ITS 2 region. Nucleotide sequences were 99% similar to Pestalotiopsis clavispora (G.F. Atk.) Steyaert. Conidia produced on potato dextrose agar medium were used to inoculate 8 plants with a spore suspension of 2.0 × 106 conidia/ml. Eight additional plants were used as control (non-inoculated). The inoculation was performed by spraying the suspension onto the leaves of Pecan seedlings and the plants were incubated for 72 h in a humid chamber (1). All inoculated plants showed symptoms 25 days after inoculation and the fungus was reisolated. The pathogenicity test was repeated once. Ten more isolates collected from four different cities in the same state were identified as Pestalotiopsis spp. by morphological characterization and pathogenicity was confirmed. Because this disease causes losses on production of nuts indirectly by reducing photosynthetically active area when the pathogen attacks leaves and directly when attacking fruits, it may restrict the production where the pathogen occurs. On some orchards in the state of Rio Grande do Sul, the attack rate reached 80% of the plants. P. clavispora has been reported causing stem end-rot of avocado in Chile (3), but this note constitutes the first report, to our knowledge, of P. clavispora causing leaf spot on C. illinoensis in Brazil. References: (1) A. C. Alfenas and F. A. Ferreira. Page 117 in: Métodos em Fitopatologia. A. C Alfenas and R. G. Mafia (eds.). Editora: UFV, Viçosa, 2007. (2) S. S. N. Maharachchikumbura et al. Fungal Diversity 50:167, 2011. (3) A. L. Valencia et al. Plant Dis. 95:492, 2011.

Insights Into the Ecological Role of Pseudomonas spp. in an Ant-plant Symbiosis

“…Pairwise interactions against human pathogens (Staphylococcus aureus and Candida albicans), a phytopathogen (Rhizopus oryzae), an entomopathogen (Metarhizium anisopliae), and Bacillus subtilis were carried out using previously described methods (Getha and Vikineswary, 2002;Visser et al, 2012). A phytopathogen fungus (Lazarotto et al, 2012;Borrero et al, 2018) identified as Pestalotiopsis clavispora FB1, isolated from Cecropia sp. leaves causing damage to the plant, was also tested.…”

Re-Isolation Methodologies for Recovering Sporulation of Eucalyptus Pestalotiopsis grandis-urophylla Isolates after 14 Months Storage

“…Pestalotiopsis sp. is considered an anamorphic fungus and their spores (conidia) are easily spread, whose penetration occurs in vegetal tissues by natural wounds or openings [9]. In this context, studies involving virulence level of different isolates and other characteristics of pathogenicity are needed [10].…”

Identification and characterization of pathogenic Pestalotiopsis species to pecan tree in Brazil

“…In severe cases, it culminates in fallen leaves and nut production losses, due to a decrease of photosynthetic area (Lazarotto et al, 2012). This pathogen has not yet been reported on pecan; however, it causes significant problems in other species of economic importance as observed for: P. microspora as a causal agent of nut black spot in Carya cathayensis (Chuanqing et al, 2010); P. clavispora causing scab disease in Psidium guajava, in Hawaii (Keith et al, 2006), and as causal agent of leaf blotch in Rosa chinensis, in China (Feng et al, 2014); and Pestalotiopsis spp.…”