Characterization of the Bull's Eye Rot of Apple in Chile

Abstract

Soto-Alvear, S (Soto-Alvear, Sylvana)[ 1,2 ] ; Lolas, M (Lolas, Mauricio)[ 2 ] . Univ Talca, Fac Ciencias Agr, Talca, Chile.Soto-Alvear, S., Lolas, M., Rosales, I. M., Chavez, E. R., and Latorre, B. A. 2013. Characterization of the bull's eye rot of apple in Chile. Plant Dis. 97:485-490. Apple fruit in Chile are primarily produced for export to Asia, Europe, and the United States, which typically requires 15 to 40 days of maritime transportation. Therefore, Chilean apple production must fulfill the sanitization requirements imposed by the receiving countries. Under these circumstances, it was important to clarify the etiology of bull's eye rot that can severely affect 'Cripps Pink' apple and other late-harvest cultivars in Chile. Based on morphological characteristics and the partial sequence analysis of the internal transcribed spacer sequences and beta-tubulin genes, Neofabraea alba was identified as the causal agent of the bull's eye rot of Chilean apple. These results were further corroborated using species-specific primers. The incidence of bull's eye rot varied considerably; for instance, in 2009, 0.0 to 58.7% in 38 Cripps Pink orchards surveyed in the relatively arid and humid apple-growing areas of Chile, respectively. There was no evidence for the presence of N. malicorticis or N. perennans, which are commonly identified as causal agents of bull's eye rot in other apple-producing countries. Altogether, these data suggest that N. alba might represent the predominant and possibly the only cause of bull's-eye rot of Chilean apple

Phenotypic, molecular and pathogenic characterization of Phlyctema vagabunda, causal agent of olive leprosy

“…Because of the difficulty in obtaining conidia on culture media, apple fruits inoculated with P. vagabunda were used to induce conidial production with successful results in accordance with previous reports (Guthrie, ; Soto‐Alvear et al ., ; Hortova et al ., ). Moreover, the time needed to produce conidia in apple fruit (30 days) coincides with that observed by Guthrie ().…”

“…() and Verkley (). However, slight differences in conidial size were observed in comparison with those obtained by several authors following the same protocol (Soto‐Alvear et al ., ; Chen et al ., ). In addition, the measurements obtained here were similar to those obtained by Rooney‐Latham et al .…”

“…Similar mycelial growth rates were registered by Soto‐Alvear et al . () on PDA at 20 °C. However, previous studies demonstrated that other culture media such as V8 juice agar (Verkley, ) or oatmeal agar (OA) (Hortova et al ., ; Chen et al ., ) are able to incite mycelial growth of P. vagabunda up to five times more than on PDA.…”

Identification of Neofabraea species causing bull's eye rot of apple in Poland and their direct detection in apple fruit using multiplex PCR

“…(), with the forward Neofab‐upTub‐100 primer corrected by Soto‐Alvear et al . (), was used for the amplification of DNA isolated from pure cultures of 19 isolates, previously identified on the basis of their β ‐tubulin sequences in this study. In PCR with the proposed primer set and an annealing temperature of 58°C, a product of the same size as that for N. alba was also observed for DNA of M. fructicola .…”

“…() for Neofabraea spp., with the corrected Neofab‐upTub‐100 primer at the 3′‐end, as suggested by Soto‐Alvear et al . (). The amplification conditions were as follows: an initial denaturation at 94°C for 3 min, followed by 35 cycles of denaturation at 94°C for 30 s, annealing at 58°C for 30 s, polymerization at 72°C for 45 s, and an extension step at 72°C for 5 min.…”