Browsing by Author "Latorre, B. A."
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- ItemEffect of boscalid on postharvest decay of strawberry caused by Botrytis cinerea and Rhizopus stolonifer(2007) Sallato, B. V.; Torres, R.; Zoffoli, J. P.; Latorre, B. A.In Chile, gray mold (Botrytis cinerea) and leak (Rhizopus stolonifir) are the major storage diseases of strawberry (Fragaria x ananassa Duch.) that considerably reduce yields and quality, limiting its international commercialization. The effect of preharvest fungicide treatments and postharvest treatments against storage decays was studied. Based on the results obtained, the incidence of B. cinerea and R. stolonifer was significantly lower on 'Camarosa' strawberry fruits treated with boscalid or boscalid + pyraclostrobin between blossom and harvest. Similarly, incidence of B. cinerea and R. stolonifer significantly decreased at 5 degrees C and 20 degrees C after immersion treatments with boscalid (600 to 700 mg L-1) or cyprodinil + fludioxonil (371 + 250 mg U). These postharvest treatments provided 5 and 15 days protection against these molds when strawberry fruits were stored at 20 degrees C and 5 degrees C, respectively. Fenhexamid (750 mg L-1) arrested B. cinerea, but it was ineffective against R. stolonifer. Variable results were obtained with iprodione (750 mg L-1). Fungicide treatments bad no adverse effect on total soluble content, titrable acidity and firmness. Only boscalid+pyraclostrobin affected the external color of the treated fruits. In conclusion, fungicide treatments using new reduced-risk fungicides can be useful to extend strawberry shelf life for over a 15 day period. However, further research is needed to establish a commercial recommendation.
- ItemFirst Report of Nothofagus macrocarpa Dieback Caused by Phytophthora citrophthora and P. nicotianae in Chile(2011) Valencia, Ana L. ; Chorbadjian, R. A. ; Latorre, B. A.The genus Nothofagus, family Nothofagaceae, comprises 36 species of trees that are native to the Southern Hemisphere. N. macrocarpa (DC.) F.M. Vásquez & R.A. Rodríguez (Roble de Santiago) is an important deciduous tree, endemic to central Chile (32 to 35°S), and found above 800 m altitude. There is an increasing interest in N. macrocarpa as an ornamental. However, a general dieback (40 to 50% prevalence) was observed at a commercial nursery in Santiago in 2009, limiting its multiplication. Symptoms are wilting, partial defoliation, reddish brown cankers on the crowns, and root necrosis. The purpose of this work was to study the etiology of the dieback in nurseries. Phytophthora was isolated from the roots and cankers of symptomatic plants (n = 3) and soil samples (using apples and avocados as baits) on amended corn meal agar (3) at 20°C for 5 days in the dark. Morphologically, P. citrophthora (Smith & Smith) Leonian, and P. nicotianae Breda de Haan were identified (2). On V8 juice agar (V8) (1), P. citrophthora formed petaloid colonies, grew between 5 and 30°C (optimum of 25°C), and produced deciduous, mono- or bipapillated sporangia of (28.1) 45.0 to 64.1 × (18.8) 32.0 to 39.2 μm. On V8, P. nicotianae produced cottony colonies, grew between 10 and 30°C (optimum of 25°C), and produced spherical, intercalary chlamydospores (mean diameter of 19.6 μm) and persistent, papillate, spherical to ovoid, ellipsoid, obpyriform sporangia of (33.2) 47.5 to 67.6 × (24.1) 30.0 to 48.9 μm. Isolates of P. citrophthora were sexually sterile, but P. nicotianae formed oogonia with amphigenous antheridia in dual cultures with P. cinnamomi (A2 compatibility type). BLAST analysis of the internal transcribed spacer (ITS) region of rDNA of isolates identified as P. citrophthora (IMI 399056 and IMI 399054, GenBank Accession Nos. JF699756 and JF699755) and P. nicotianae (IMI 399055, Accession No. JF699757), amplified by PCR using ITS universal primers (4), revealed 100% similarity with reference isolates of P. citrophthora (Accession Nos. GU259324.1 and GU259317.1) and P. nicotianae (Accession No. GU983635.1). P. citrophthora (n = 2) and P. nicotianae (n = 1) were pathogenic when wounded detached twigs (n = 5) of N. macrocarpa and N. obliqua were inoculated with 20 μl of a mycelial suspension (10 6 CFU/ml) of either Phytophthora spp. Twigs were placed in a moist chamber at 20°C for 12 days prior to determine the length of the necrotic lesions that developed. An equal number of noninoculated twigs were left as control. Reisolation of P. citrophthora and P. nicotianae from inoculated material was 100%. The length of the necrotic lesions (13 to 80 mm) from inoculated N. macrocarpa and N. obliqua was significantly greater (P < 0.05) compared with the controls. Regardless of Phytophthora isolates, necrotic lesions (53.9 ± 15.8 mm) in infected N. macrocarpa were significantly longer than in N. obliqua (28.6 ± 13.1 mm) (P < 0.0001). To our knowledge, this is the first report of P. citrophthora and P. nicotianae associated with dieback on N. macrocarpa in Chile. Therefore, there is a potential risk of Phytophthora dieback in N. macrocarpa in nature. References: (1) J. Ampuero et al. Plant Dis. 92:1529, 2008. (2) D. C. Erwin and O. K. Ribeiro. Phytophthora Diseases Worldwide. The American Phytopathological Society, St. Paul, MN, 1996. (3) B. A. Latorre and R. Muñoz. Plant Dis. 77:715, 1993. (4) T. J. White et al. PCR Protocols: A Guide to Methods and Applications. Academic Press, San Diego, 1990.
- ItemIdentification of Phytophthora cryptogea as the Cause of Rapid Decline of Petunia (Petunia x hybrida) in Chile(AMER PHYTOPATHOLOGICAL SOC, 2008) Ampuero, J.; Latorre, B. A.; Torres, R.; Chavez, E. R.Phytophthora cryptogea was consistently isolated from diseased tissue taken from the crown and necrotic roots of grandiflora type petunia (Petunia x hybrida) that were collected in gardens in five Public parks in Santiago. Chile in 2004 and 2005. Symptoms included leaf wilting and foliar chlorosis. followed by partial necrosis. and extensive dark-brown to reddish cankers in the crown. Disease incidence was over 50% and infected plants died within 7 to 10 days after transplanting. This pathogen was identified oil the basis of colony morphology. morphological characterization of the sexual and asexual reproductive structures, and temperature range. The identification of Phytophthora cryptogea was further corroborated by the internal transcribed spacer sequence analysis (GenBank accession number EF093534). Isolates of P cryptogea were pathogenic oil 10-week-old white grandiflora petunia plants that were inoculated on the roots or on the crown using mycelium fragments, or via soil inoculation using zoospores. A rapid decline was observed after soil inoculation,, with zoospores. Root fresh weight decreased significantly and the root rot index and severity of foliage symptoms increased significantly (P <= 0.051), relative to noninoculated plains after 14 days Of incubation. Two isolates (Ph-1 and Ph-2) were pathogenic oil bell pepper and one isolate (Ph-1) was pathogenic oil tomato after root inoculation. Two isolates (Ph-2 and Ph-3) were pathogenic oil the fruit of avocado, bell pepper. cherry tomato. Cucumber. kiwifruit, lemon. pear. pepino, and potato tubers, demonstrating the pathogen's ability to cause postharvest infection of fruit of a wide range of host plants. The efficacy of mefenoxam at 0.1 mg/ml mixed with either chlorothalonil at 1.0 mg/ml or mancozeb at 1.6 mg/ml was demonstrated in this study. whereas chlorothalonil and mancozeb alone did not control disease development. No significant differences were obtained between foliage and soil drench applications,. This study demonstrated that P. cryptogea is the cause of the rapid decline found on petunia in Santiago. Chile and, to our knowledge. this is the first report giving a detailed description of a disease caused by P. cryptogea on petunia.
- ItemIncrease in Cladosporium spp. populations and rot of wine grapes associated with leaf removal(ELSEVIER SCI LTD, 2011) Latorre, B. A.; Briceno, E. X.; Torres, R.Leaf removal reduces the epiphytic populations of several filamentous fungi found on grapevine (Vitis vinifera) Consequently this practice is used to prevent foliar diseases of grapevines and rots of grapes In this study the effects of leaf removal on Cladosporium rot (Cladosporium cladosporioides and Cladosporium herbarum) which often affects Cabernet Sauvignon in Chile were characterized The effects of leaf removal on epiphytic populations of Cladosporium spp on grape berry surfaces and on Cladosporium rot development were investigated Three leaf removal treatments were compared (i) severe leaf removal where leaves from two to three nodes above opposite and from all nodes below clusters were removed (ii) mild leaf removal where leaves opposite each cluster were removed and (iii) no leaf removal Regardless of the leaf removal treatment low population levels of Cladosporium spp were detected early in the ontogenic development of grape berries which increased as the berries matured reaching maximum populations on overripe berries Based on our results severe leaf removal favors the growth of Cladosporium spp on grape berries and increases the prevalence of Cladosporium rot at harvest This increase in Cladosporium spp was correlated with an increase in lenticel damage in Cabernet Sauvignon and Sauvignon blanc vines subjected to severe leaf removal Considering that Cladosporium rot significantly reduces yield and wine quality, farmers should avoid continuous exposure of grape clusters to sunlight in order to prevent severe outbreaks of Cladosporium rot (C) 2010 Elsevier Ltd All rights reserved
- ItemNeofusicoccum spp. Associated with Stem Canker and Dieback of Blueberry in Chile(AMER PHYTOPATHOLOGICAL SOC, 2009) Espinoza, J. G.; Briceno, E. X.; Chavez, E. R.; Urbez Torres, J. R.; Latorre, B. A.Blueberry (Vaccinium spp.) plantings have significantly increased in Chile during the last decade and, currently, over 10,700 ha are cultivated throughout the country. Among other diseases, stein canker and dieback has been frequently observed in commercial plantations with incidences between 15 and 45%. The aim of this study was to identify and characterize Neofusicoccum spp. causing stem canker and dieback of blueberry in Chile. Three species, N. arbuti, N. australe, and N. parvum, were identified based oil colony and conidia morphology, and nucleotide sequence analysis of the internal transcribed spacer (ITS) region (ITS 1-5.8S-ITS2). These Neofusicoccum spp. were found alone or coexisting with Pestalotiopsis spp., Truncatella spp., or Phomopsis spp. Koch's postulates showed all Neofusicoccum spp. isolated from infected plants to be pathogenic when inoculated on blueberry fruit and twigs using both mycelia and conidia suspension. All blueberry cultivars tested, including, Brigitta, Bluecrop, Brightwell, Duke, Elliott, Misty, and O'Neal, were susceptible to Neofusicoccum spp. infection. Pathogenicity tests showed N. parvum to be the most virulent species and Elliott to be the most susceptible cultivar. This report represents the first description of N. arbuti, N. australe, and N. parvum as canker-causing agents on blueberry in Chile.
- ItemTable grape (Vitis vinifera L.)(Woodhead, 2011) Zoffoli Guerra, Juan Pablo; Latorre, B. A.Table grapes produce clusters of berries on deciduous woody vines. The berries are simple non-climacteric fleshy fruits. Currently, 'Thompson Seedless', 'Red Globe' and 'Flame Seedless' are the main cultivars worldwide. The growth period lasts for 100 to 120 days after full bloom, and grapes are harvested with 15 to 17% total soluble solids (TSS) and/or a TSS: titratable acidity ratio greater than 20. Several biotic and abiotic factors cause postharvest deterioration of grapes, particularly when grapes are transported to markets involving a journey of 15 to 40 days. The critical factors involved in postharvest handling and management of table grapes are reviewed and discussed in this chapter.
- ItemThe risk assessment index in grape powdery mildew control decisions and the effect of temperature and humidity on conidial germination of Erysiphe necator(2007) Bendek, C. E.; Campbell, P. A.; Torres, R.; Donoso, A.; Latorre, B. A.Powdery mildew (Erysiphe necator) is a major disease of grapevines (Vitis vinifera) in Chile. Severe outbreaks have occurred recently despite the use of strict fungicide programs to control it. The objectives of this study were to evaluate the infection risk assessment index (RAI), to predict conditions for E. necator infection, and to study the effect of temperature (T), relative humidity (RH) and free moisture (FM) on conidial germination and disease development. Conidial germination was affected by T, RH, and FM. There were significant (p < 0.001) interactions between E. necator isolates and T and between isolates and RH. Conidial germination was optimal at 25 degrees C. There was no germination at 5 degrees C and 35 degrees C. At 20 degrees C, conidia germinated at a low RH (33-35%). Germination increased at a RH between 47 and 90% but decreased at higher RHs. Powdery mildew development on Carmenere,Chardonnay,and Merlot vines increased linearly from 6 degrees C to 23 degrees C. These grape cultivars were all equally susceptible to E. necator. Incubation periods varied. It was 13 to 14 d at 20 degrees C or 23 degrees C, 19 to 24 d at 10 degrees C, and more than 23 d at 6 degrees C. Grape powdery mildew was markedly decreased when inoculated leaves were wet at 1 or 72 h post inoculation. In conclusion, RAI, determined on the basis of air T, was useful to decide on fungicide applications between grape bud burst and veraison in Chile.