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Browsing by Author "Latorre, Bernardo A."

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Canker and twig dieback of blueberry caused by Pestalotiopsis spp. and a Truncatella sp in Chile
(AMER PHYTOPATHOLOGICAL SOC, 2008) Espinoza, Jose G.; Briceno, Erika X.; Keith, Lisa M.; Latorre, Bernardo A.
Blueberry (Vaccinium spp.) has great economic importance in Chile, which currently has about 8,500 ha being cultivated. Recently, the presence of canker and dieback symptoms has been observed along the productive blueberry zone of Chile. Species of Pestalotiopsis and Truncatella were consistently isolated from diseased samples in 22 different locations. Therefore, the objective of this study was to identify and characterize the species of Pestalotiopsis and Truncatella associated with canker and twig dieback symptoms on blueberry. Forty-nine isolates were ob- tained on acidified potato dextrose agar in 2006 and 2007. These isolates were identified as Pestalotiopsis clavispora, P neglecta, and Truncatella (=Pestalotia) angustata on the basis of colony characteristics and conidial morphology. This identification was verified by internal transcribed spacer analysis of DNA. Isolates of P. clavispora, P. neglecta, and T angustata were pathogenic on apple, kiwifruit, and blueberry fruit. Similarly, isolates of P. clavispora were pathogenic on detached blueberry twigs of cv. O'Neal. Additionally, three selected isolates of P. clavispora induced light-brown canker lesions, surrounded by a reddish halo, and shoot dieback after twig inoculations on 2-year-old twigs of blueberry cvs. O'Neal, Bluecrop, Brightwell, Brigitta, Duke, Elliot, and Misty. Among blueberry cultivars, Brightwell and O'Neal were the most susceptible and Bluecrop and Misty the least susceptible, while Elliot, Brigitta, and Duke were moderately susceptible to P. clavispora. These pathogens were isolated consistently from inoculated plants, confirming Koch's postulates. P. clavispora was highly sensitive to fludioxonil and pyraclostrobin with a median effective concentration of 0.06 to 0.08 and 0.04 to 0.8 mu g/ml, respectively. Therefore, the results of this study indicate that P. clavispora, P. neglecta, and T angustata are primary pathogens that can cause canker lesions and dieback symptoms on blue- berry not previously described in Chile. However, these results do not exclude that other species of these genera or other plant-pathogenic fungi (e.g., Botryosphaeria, Pestalotia, and Phomopsis spp.) may eventually be involved in this syndrome of blueberry.
Characterization of Botrytis cinerea and B. prunorum From Healthy Floral Structures and Decayed 'Hayward' Kiwifruit During Post-Harvest Storage
(AMER PHYTOPATHOLOGICAL SOC, 2021) Riquelme, Danae; Aravena, Zdenka; Valdes Gomez, Hector; Latorre, Bernardo A.; Diaz, Gonzalo A.; Pablo Zoffoli, Juan
Gray mold is the primary postharvest disease of 'Hayward' kiwifruit (Actinidia deliciosa) in Chile, with a prevalence of 33.1% in 2016 and 7.1% in 2017. Gray mold develops during postharvest storage, which is characterized by a soft, light to brown watery decay that is caused by Botrytis cinerea and B. prunorum. However, there is no information on the role of B. prunorum during the development and storage of kiwifruit in Chile. For this purpose, asymptomatic flowers and receptacles were collected throughout fruit development and harvest from five orchards over two seasons in the Central Valley of Chile. Additionally, diseased kiwifruits were selected after storage for 100 days at 0 degrees C and 2 days at 20 degrees C. Colonies of Botrytis sp. with high and low conidial production were consistently obtained from apparently healthy petals, sepals, receptacles, and styles and diseased kiwifruit. Morphological and phylogenetic analysis of three partial gene sequences encoding glyceraldehyde-3-phosphate dehydrogenase, heat shock protein 60, and DNA-dependent RNA polymerase subunit II were able to identify and separate B. cinerea and B. prunorum species. Consistently, B. cinerea was predominantly isolated from all floral parts and fruit in apparently healthy tissue and diseased kiwifruit. During full bloom, the highest colonization by B. cinerea and B. prunorum was obtained from petals, followed by sepals. In storage, both Botrytis species were isolated from the diseased fruit (n = 644), of which 6.8% (n = 44) were identified as B. prunorum. All Botrytis isolates grew from 0 degrees C to 30 degrees C in vitro and were pathogenic on kiwifruit leaves and fruit. Notably, B. cinerea isolates were always more virulent than B. prunorum isolates. This study confirms the presence of B. cinerea and B. prunorum colonizing apparently healthy flowers and floral parts in fruit and causing gray mold during kiwifruit storage in Chile. Therefore, B. prunorum plays a secondary role in the epidemiology of gray mold developing in kiwifruit during cold storage.
Characterization of Cladosporium Rot in Grapevines, a Problem of Growing Importance in Chile
(AMER PHYTOPATHOLOGICAL SOC, 2008) Briceno, Erika X.; Latorre, Bernardo A.
Cladosporium rot (Cladosporium spp.) of grapevine (Vitis vinifera) is a common disease in Chile, particularly in Cabernet Sauvignon and other red wine grape cultivars. It is favored by delayed harvest to obtain the phenolic maturity necessary for high-quality red wine. This study expands oil previous investigations of the specific causal agents, the histopathological host:pathogen relationship, and the population dynamics of Cladosporium spp. during the seasonal development of grape clusters. Over 100 isolates were obtained and identified as C cladosporioides and C herbarum, confirming previous results. The identity of a subset of isolates was confirmed by molecular analysis. Isolates of both C cladosporioides and C herbarum from grapevines were pathogenic on inoculated table grapes and wine grapes. These pathogens were reisolated, fulfilling Koch's Postulates. Berry injuries and total soluble solids content above 15% were necessary for Cladosporium spp. to infect wine grapes. The mycelia of C cladosporioides and C. herbarum grew between 0 and 30 degrees C, but no growth was obtained at 35 degrees C in vitro. The histological studies showed that Cladosporium spp. superficially colonize mature V. vinifera berries, invading the epidermis but scarcely penetrating the hypodermis. The Cladosporium populations obtained on apparently healthy berries of V. vinifera cvs. Cabernet Sauvignon and Chardonnay were significantly larger (P = 0.05) than the populations obtained under similar conditions on berries of V. champini cv. Ramsey and hybrids Kober 5BB and Couderc 1613. Considering the importance of Cladosporium rot in Chile compared with other grape production areas, the development of control strategies is needed to prevent high disease severity, which affects both yield and wine quality.
Duration of the susceptibility of pruning wounds of different ages to infections by Phaeomoniella chlamydospora on grapevine cv. Cabernet Sauvignon in Central Chile
(2022) Diaz, Gonzalo A.; Latorre, Bernardo A.
Grapevine trunk diseases (GTDs) are one of the most important phytosanitary problems that affect grapevines (Vitis vinifera) worldwide. In Chile, Phaeomoniella chlamydospora is the major fungal trunk pathogen associated with GTDs. In the vineyards, the natural infections by P. chlamydospora are associated with air-borne conidia dispersed onto fresh pruning wounds from pycnidia. These pruning wounds are considered an important entrance for fungal trunk pathogens such as P. chlamydospora in the host in the field. However, the duration of the susceptibility of grapevine annual pruning wounds to P. chlamydospora is still unknown in Chile. Therefore, this study aimed to evaluate the period of susceptibility of pruning wounds of different ages to artificial infection of P. chlamydospora on grapevine cv. Cabernet Sauvignon, Central Chile. Artificial inoculations of a conidial suspension (10(5) conidia/mL) of P. chlamydospora were used to determine the susceptibility of pruning wounds of different ages, from 1, 15, 30, and 45 days after pruning. The experiments were conducted on lignified cuttings in a greenhouse, and on vine spurs in two vineyards (Buin and Nancagua, Central Chile) during two consecutive seasons. The results indicated that the pruning wounds of grapevine cv. Cabernet Sauvignon were very susceptible to infections by P. chlamydospora, with a percentage of pruning wounds infected from 97 to 71% for cuttings, and 96% to 60% for spurs, during the first 15 days after pruning. However, the susceptibility of pruning wounds of different ages in cuttings and spurs of grapevine, generally decreased as the time from pruning to inoculation increased. Moreover, the pruning wounds the pruning wounds remained susceptible to artificial inoculation by P. chlamydospora for up 45 days after pruning with percent of wounds infected from 8.0 to 12.2, and 8.3 to 18.8% on cuttings and spurs of grapevine, respectively. Finally, this study constitutes study constitutes the first research focalized on the susceptibility of pruning wounds of various ages of grapevine cv. Cabernet Sauvignon to artificial inoculations by P. chlamydospora in Central Chile.
Effect water activity on in vitro mycelial growth of Neofusicoccum spp. infecting blueberry
(2012) Latorre, Bernardo A.; Diaz, Gonzalo A.; Reed, Maria P.
B.A. Latorre, G.A. Diaz, and M.P. Reed. 2012. Effect of water activity on mycelial growth of Neofusicoccum spp. infecting blueberry. Cien. Inv. Agr. 39(1): 221-228. Stern canker in blueberries Vaccinium corymbosum L.) is a disease which is widely distributed around the world and of growing importance in Chile, associated with Neofusicoccum species. The purpose of the present work was to study the effects of water activity (a(w)) and temperature on mycelial growth in vitro of N. arbuti, N. australe and N. parvum, obtained from blueberries with symptoms of stem canker. According to the results obtained, 25 degrees C was the optimum temperature for mycelial growth of)V. arbuti, N. australe and N. parvum. These species presented minimal growth at 35 degrees C and none at 0 and 5 degrees C. The effect of a(w) on mycelial growth was significant (P <= 0.001) and varied with the species of Neofusicoccum and the temperature. At 25 degrees C, the optimum temperature, the three species of Neofusicoccum presented minimum growth with a(w) of 0.900 and 0.920, while optimum mycelial growth was found with a(w) equal to 0.990. Independent of the Neofusicoccum species, the effect of temperature (T) and a(w) on mycelial growth was best explained by y = -721.62 + 0.24T + 788.92(w), (R-adj(2) = 0.77, P <= 0.001), suggesting that T and a(w) jointly explained 77% of the total variation on mycelial growth of Neofusicoccum spp. The results obtained provide important information for a better understanding of the biology of these plant pathogenic fungi, and suggest that temperature and a could be important parameters for understanding factors that affect the inoculum production, colonization and infection by Neofusicoccum spp. in blueberry plantations.
Evaluation of DMI fungicides against species of Diplodia and Neofusicoccum associated with Botryosphaeria canker of grapevine
(2013) Torres, Carolina; Latorre, Bernardo A.; Undurraga, Pedro; Besoain, Ximena
C. Torres, B.A. Latorre, P. Undurraga, and X. Besoain. 2013. Evaluation of DMI fungicides against species of Diplodia and Neofusicoccum associated with Botryosphaeria canker of grapevine. Cien. Inv. Agr. 40(1):131-138. The Botryosphaeriaceae species have been widely studied and are considered a serious problem to the production of grapes worldwide. To aid in the development of control strategies for these fungi, in vitro experiments were conducted to evaluate the effectiveness of demethylation inhibiting (DMI) fungicides against Diplodia seriata, D. mutila, Neofusicoccum australe and N. parvum isolated from grapevine (Vitis vinifera). Fungicidal effectiveness was evaluated over a range of increasing concentrations using measurements of both the inhibition of conidial germination and the effects on mycelial growth. The effective concentrations (EC) necessary to inhibit conidial germination and mycelial growth by 50% (EC50) and 90% (EC90) were estimated by linear regression analysis between x = log(10), of the fungicidal concentration and y = the Probit value of the inhibition percentage. The results demonstrate that tebuconazole, myclobutanil, prochloraz and prochloraz plus epoxiconazole exhibit considerable in vitro activity against D. mutila, D. seriata, N. australe and N. parvum. These DMI compounds were able to arrest conidial germination and inhibit mycelial growth. The EC50 values obtained for conidial germination were generally higher than the EC50 values obtained for mycelial growth, suggesting that mycelia are more sensitive to the DMI compounds than are conidia. However, the effectiveness of these DMI compounds in the vineyard must be studied before any final conclusions can be reached.
Infection Caused by Phaeomoniella chlamydospora Associated with Esca-like Symptoms in Grapevine in Chile
(2014) Diaz, Gonzalo A.; Latorre, Bernardo A.
Trunk diseases such as esca have been recognized as an economically important problem of grapevine worldwide. A study was conducted to characterize the distribution of Phaeomoniella chlamydospora in Chile. A field survey of young and mature grapevines from 67 vineyards located along a 1,315-km north-south axis demonstrated that P chlamydospora was present in 94.9% of the grapevine samples showing the black-wood streaking symptom (BWS) but not the characteristic foliar symptoms of esca. Phylogenetic analysis of the ribosomal DNA internal transcribed spacer (ITS) combined with beta-tubulin (BT) genes grouped Chilean isolates together with reference isolates from South Africa and the United States, whereas Spanish isolates were clustered separately. Chilean isolates differed by only 2 to 3 bp for BT and ITS, respectively. Conidia germinated at 5 to 35 degrees C, with an optimal temperature of 25 to 30 degrees C. Isolates were pathogenic, and Koch's postulates were fulfilled in separate sets of inoculations of axenic plantlets, cuttings, 2-year-old plants, spurs, and shoots of V. vinifera. This study showed that P. chlamydospora was associated consistently with BWS and no other apparent symptom in young and mature grapevines, including nursery plants, in Chile. Inoculum was absent from the soil, grapevine pruning debris, sap samples, and herbaceous weeds, which is in contrast to past studies. At this time, Vitis spp. are the only known hosts of P. chlarnydospora in Chile.
Low Occurrence of Patulin-Producing Strains of Penicillium in Grapes and Patulin Degradation during Winemaking in Chile
(AMER SOC ENOLOGY VITICULTURE, 2011) Diaz, Gonzalo A.; Yanez, Lina; Latorre, Bernardo A.
Penicillium expansum has emerged as the cause of storage decay of table grapes (Vitis vinifera) and has been frequently isolated from apparently healthy clusters of grapes in Chile. The objectives of this study were to identify patulin-producing strains of Penicillium associated with winegrapes and wineries in Chile and to determine the potential presence of patulin in wines made with grapes infected with P. expansum. In this study, P. brevicompactum, P. expansum, and P. glabrum were identified on apparently healthy grape clusters and in the air of vineyards and wineries. Of 132 Penicillium isolates, 4 P. brevicompactum and 11 P. expansum strains were patulin-producing, determined by HPLC-UV/DAD. Patulin was also detected in Cabernet Sauvignon musts produced with grapes contaminated with a patulin-producing strain of P. expansum. However, patulin concentrations decreased during fermentation by 67.3 to 83.3%. Overall, the frequency of P. expansum isolation from grapes was relatively low; thus, considering the rapid degradation of patulin produced during fermentation, the risk of patulin contamination of bottled wine appears to be low.
Ochratoxigenic Aspergillus species on grapes from Chilean vineyards and Aspergillus threshold levels on grapes
(ELSEVIER, 2009) Diaz, Gonzalo A.; Torres, Rene; Vega, Mario; Latorre, Bernardo A.
This study reports the incidence of ochratoxigenic strains of Aspergillus on Chilean grapes (Vitis vinifera) and wineries, and production of OTA levels in wines with grapes having different levels of contamination with OTA-producing Aspergillus carbonarius was studied. A. carbonarius, A. niger, A. niveus, A. paradoxus, A. versicolor, A. wentii, and A. westerdijkiae were identified on apparently healthy clusters of red and white grape cultivars. However, A. carbonarius and A. niger were the most frequently identified species, mow abundant on red than white grape cultivars. Aspergillus spp. populations increased between veraison and harvest, but the isolation frequencies were relatively low over the entire growing season. At the winery, A. carbonarius, A. niger and A. westerdijkiae were occasionally found in the air, exclusively during winemaking. OTA-producing strains were only found among isolates of A. carbonarius, A. niger, A. wenti, and A. westerdijkiae. producing 2 to 17 mu g/L of OTA in liquid medium; however, A. westerdijkiae produced the highest OTA concentration in vitro. Red wines elaborated with 0.5% of grapes infected with an OTA-producing strain of A. carbonarius (Aspuc-SB36) exceeded the 2 mu g/L of OTA tolerance established for wines by the European Community. Therefore, a threshold below 0.5% infected berries is proposed for red wines. ELISA tests proved to be useful for detecting OTA in broth culture as in wine samples. (C) 2009 Elsevier B.V. All rights reserved.
Pre- and post-infection activity of new fungicides against Botrytis cinerea and other fungi causing decay of table grapes
(PONTIFICIA UNIV CATOLICA CHILE, FAC AGRONOMIA INGENIERIA FORESTAL, 2007) Serey, Ricardo A.; Torres, Rene; Latorre, Bernardo A.
Pre- and post-harvest diseases restrict table grape production and exports (Vitis vinifera L.) in Chile, with the most important disease being grey mold (Botrytis cinerea). In addition, rot due to Aspergillus niger, Cladosporium herbarum, Penicillium expansum, and Rhizopus stolonifer frequently occurs. The pre- and post-infection activity of fungicides against these pathogens was studied on Thompson Seedless table grapes. Detached, mature, berries were used, and inoculations were performed with 20 mu L of a 10(6) spores.mL(-1) Suspension placed on three punctures aseptically made at the calyx end of each berry. Fungicides used (per liter) were boscalid (600 mg), boscalid (200 mg) + pyraclostrobin (100 mg), boscalid (200 mg) + kresoxim methyl (100 mg). cyprodinil (60 mg) + fludioxonil (40 mg), BAS 600 KBF (100 mg) + metrafenone (150 mg), BAS 600 KBF (200 mg) + boscalid (300 mg), BAS 600 KBF (100 mg) + pyraclostrobin (100 mg), and captan (400 mg). Each fungicide was applied either by drop (12 mu L.berry(-1)) placed on three Punctures made with a sterile hypodermic needle or by 60 s immersion. Berries were then incubated in humid chambers at 20 degrees C. The pre-infection (protection) activity of the fungicides varied considerably among the pathogens tested and was found to be significant (p < 0.001) and, with one exception (A. niger), it was significantly (p < 0.002) affected by the application method. The interaction between fungicide and application method was only significant (p < 0.001) for R. stolonifer at 48 h post treatment. In general, pre-infection activity gave 0 to 4 days protection after drop applications and 0 to 21 days after immersion treatments. The post-infection (curative) activity varied among pathogens and fungicide treatments. However, it was always below 24 h.
Preharvest applications of growth regulators and their effect on postharvest quality of table grapes during cold storage
(ELSEVIER, 2009) Zoffoli, Juan Pablo; Latorre, Bernardo A.; Naranjo, Paulina
Over 54,600 ha of table grapes (Vitis vinifera), mainly cvs. 'Thompson Seedless', 'Flame Seedless' and 'Redglobe', are planted in Chile. Almost the entire production is exported to the USA, Europe, Asia, or one of several Latin American countries, which typically requires 15-40d of maritime transportation. During this period, several physical, physiological, and pathological factors cause table grape deterioration. Because berry size is the main quality factor in international markets, farmers often overuse the growth regulators, gibberellic acid (GA(3)) and forchlorfenuron (CPPU), in an effort to increase berry size. We examined the effect of preharvest growth regulators on seedless ('Thompson Seedless', and 'Ruby Seedless') and seeded ('Redglobe') table grape cultivars during cold (0 degrees C) storage plus a shelf life period of 3 d at 20 degrees C. The overuse of GA(3), eight instead of two GA(3) applications on Thompson Seedless, and the use of one GA(3) application on Redglobe and 'Ruby Seedless', increased berry pedicel thickness and lowered cuticle content but induced shatter and predisposed grapes to gray mold caused by Botrytis cinerea. In contrast, CPPU increased berry pedicel thickness and cuticle content but did not increase shatter or gray mold incidence. Clusters that were subjected to overuse of combined GA(3) and CPPU were highly sensitive to shatter, had the thickest pedicel, and developed a high gray mold incidence during cold storage. Hairline, a fine cracking developed during cold storage, was induced on 'Thompson Seedless' and 'Ruby Seedless' by growth regulators, but no hairline occurred on 'Redglobe' table grapes. Therefore, berry quality during cold storage is greatly influenced by growth regulator management in the vineyard. (C) 2008 Elsevier B.V. All rights reserved.
Prevalence and pathogenicity of fungi associated with grapevine trunk diseases in Chilean vineyards
(2013) Díaz, Gonzalo A.; Auger, Jaime; Besoain, Ximena; Bordeu, Edmundo; Latorre, Bernardo A.
Prevalence of isolates of Botrytis cinerea resistant to multiple fungicides in Chilean vineyards
(ELSEVIER SCI LTD, 2012) Latorre, Bernardo A.; Torres, Rene
Gray mold (Botrytis cinerea) is an important disease of grapevines (Vitis vinifera) and requires several fungicide treatments to achieve a satisfactory control in Chile. Furthermore, a high resistance risk has developed because of the extensive use of specific fungicides with a single-site mode of action. The aim of this study was to determine the presence of resistance to the multiple fungicides currently used against B. cinerea in Chile. During 2007-2009 and 2011, 214 isolates of B. cinerea from 36 commercial vineyards were examined for sensitivity to anilinopyrimidines (cyprodinil or pyrimethanil), demethylation inhibitors (DMIs) (tebuconazole), hydroxyanilides (fenhexamid) and phenylpyrroles (fludioxonil). Of all of the isolates, 62.7% were resistant to anilinopyrimidines, 7.2% to DMIs, 27.1% to hydoxyanilides and 44.8% to phenylpyrrole derivates. Overall, 16 (12.3%) of the isolates were sensitive; although none was resistant to all four of the fungicide classes, and 50 (38.5%), 51(39.2%), and 13 (10.0%) isolates were resistant to one, two and three fungicides, respectively. In vitro, resistant isolates were capable of causing fruit rot on wounded apples pretreated with any one of the five fungicides at label concentrations. To the best of our knowledge, this is the first report of isolates having simultaneous resistance to anilinopyrimidines, DMIs, phenylpyrroles and hydroxyanilides in B. cinerea populations from grapevines in Chile. Therefore, fungicide resistance is a serious problem that questions the sustainability of the current gray mold control strategy, which relies almost exclusively on fungicides with single-site modes of action. (C) 2012 Elsevier Ltd. All rights reserved.

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