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L W Timmer - One of the best experts on this subject based on the ideXlab platform.
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effect of lesion age humidity and fungicide application on sporulation of alternaria alternata the cause of Brown Spot of tangerine
Plant Disease, 2006Co-Authors: R. F. Reis, S. N. Mondal, A De Goes, Turksen Shilts, Francis C Brentu, L W TimmerAbstract:ABSTRACT Alternaria Brown Spot, caused by Alternaria alternata, causes yield losses and fruit blemishes on many tangerines and their hybrids in most citrus areas of the world where susceptible cultivars are grown. Although the conditions affecting infection and disease severity are known, little information is available on inoculum production on infected tissue. We found that sporulation on leaves began about 10 days after symptoms developed, was abundant from 20 to 40 days, and declined thereafter. Conidial production was far greater on leaf than on fruit or twig lesions. Spore production per unit area of leaf lesion was greater on the more susceptible hybrids, Minneola and Orlando tangelos, than on the less susceptible Murcott tangor. At 74% relative humidity, conidial production on leaf lesions was low, but it was abundant at 85, 92.5, 96, and 100%. Application of QoI or copper fungicides, but not ferbam, suppressed sporulation on leaf lesions for about 14 to 21 days after application. Additional appli...
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first report of alternaria Brown Spot of citrus caused by alternaria alternata in peru
Plant Disease, 2006Co-Authors: J E Marin, Tobin L Peever, H S Fernandez, Natalia A Peres, M Andrew, L W TimmerAbstract:Alternaria Brown Spot, caused by Alternaria alternata (Fr.) Keissler, causes leaf, twig, and fruit lesions and reduces yield and fruit quality of many tangerines (Citrus reticulata Blanco) and their hybrids (3). In 2003, characteristic symptoms of Brown Spot were observed on young leaves and fruit of 'Minneola' tangelo in the Satipo Province of Peru. In 2004, the disease was discovered in the provinces of Chanchamayo, Leoncio Prado, and La Convencion in the Junin, Huanuco, and Cusco regions, respectively, as well as in the Apurimac and the Ene valleys. In 2005, it was confirmed in the province of Oxapampa in the Pasco Region. Brown-to-black lesions surrounded by yellow halos and veinal necrosis were observed on young leaves, often causing abscission of young shoots and twig dieback. Light Brown, circular lesions were observed on fruit, and when severe, resulted in premature abscission. Isolations from infected leaves and twigs were made on potato dextrose agar (PDA) with 10 μg/ml of benomyl. Colonies that developed after 5 days at 27°C were olive Brown-to-black and produced small, muriform, pigmented conidia typical of A. alternata. On PDA without benomyl, gray colonies with conidia typical of Colletotrichum gloeosporioides were recovered frequently. Inoculation of three detached young shoots of 'Minneola' by spraying with a suspension of 105 conidia/ml of A. alternata produced leaf and twig symptoms characteristic of the disease after 48 h and confirmed pathogenicity of three isolates. Symptoms were not observed on control leaves sprayed with water nor on an equal number of leaves inoculated with a suspension of 105 conidia/ml of C. gloeosporioides. Reisolation of A. alternata from diseased tissue fulfilled Koch's postulates. DNA was extracted from 17 isolates and a partial endopolygalacturonase gene was amplified and sequenced (2). Sequences of all 17 isolates were identical, and in BLAST searches of the NCBI database, the closest matches were A. alternata accession nos. AY295023.1, AY295022.1, and AY295021.1 with 100, 99.8, and 99.8% sequence similarity, respectively. Phylogenetic analyses revealed that all isolates from Peru clustered with Brown Spot isolates from Israel, Turkey, South Africa, and Australia (1). These results, along with morphological characterization and pathogenicity tests, confirm the identity of the fungus as the tangerine pathotype of A. alternata. The disease has significantly reduced yield and the commercial value of fruit and may be a limiting factor for the production of susceptible cultivars in those areas of Peru. References: (1) T. L. Peever et al. Phytopathology 92:794, 2002. (2) T. L. Peever et al. Mycologia 96:119, 2004, (3) L.W. Timmer et al. Pages 19-21 in: Compendium of Citrus Diseases. 2nd ed. L. W. Timmer et al eds. The American Phytopathological Society, St. Paul, MN, 2000.
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evaluation of the alter rater model for spray timing for control of alternaria Brown Spot on murcott tangor in brazil
Crop Protection, 2006Co-Authors: Natalia A Peres, L W TimmerAbstract:Abstract Alternaria Brown Spot, caused by Alternaria alternata, recently appeared in Brazil and is now causing serious damage to Murcott tangors in Sao Paulo State. The Alter-Rater model and other systems for timing fungicide applications as well as different fungicide programs were evaluated in two seasons in different citrus-growing areas of Sao Paulo State. Alternaria Brown Spot severely reduced yields of Murcotts in the unsprayed controls in both years. Fungicide applications reduced fruit drop and increased yields in many cases. Regression analyses showed that yield declined as disease severity increased. A copper fungicide applied according to the Alter-Rater model with a trigger value of 50 required one to two more applications than a calendar program in both locations in 2002–03. Use of the Alter-Rater 50 increased the number of fruit harvested in both locations, but did not improve fruit quality when compared to the calendar program. Use of the Alter-Rater with trigger values of 100 or 150, or the Copper model forecast fewer sprays and resulted in poor disease control and low yields. In a test in 2003–04, fungicide applications timed with the Alter-Rater 50 were no more effective than calendar sprays. Copper fungicides throughout the season or programs with copper applied early followed by dithiocarbamates or QoI fungicides later provided better disease control than a full-season mancozeb program. Murcott product in some citrus growing areas in Brazil will be possible only if the value of the crop is sufficient to justify 10 or more fungicide applications per year.
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evaluation of the alter rater model for timing of fungicide applications for control of alternaria Brown Spot of citrus
Plant Disease, 2003Co-Authors: Alka Bhatia, Pamela D Roberts, L W TimmerAbstract:ABSTRACT Alternaria Brown Spot, caused by Alternaria alternata, results in serious yield losses of tangerines and their hybrids in Florida. The Alter-Rater model predicts the need for fungicide applications based on daily cumulative points that are assigned on the basis of rainfall, leaf wetness, and temperature. Previously, Alter-Rater threshold or trigger values of 50, 75, 100, and 150 points for application of copper fungicides were suggested for groves with different cultivars and disease histories. In this study, we evaluated thresholds of 50, 100, and 150 points in four Minneola tangelo and Murcott tangor groves in 2000 and 2001. For comparison, copper fungicides were applied according to the DISC Copper Model in 2000 and according to calendar sprays in 2001. Use of the Alter-Rater model resulted in fewer sprays in three of the four groves in 2000 and better fruit quality in the other grove than the Copper Model. Compared to a calendar spray schedule in 2001, use of the Alter-Rater model resulted in...
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outbreaks of alternaria Brown Spot of citrus in brazil and argentina
Plant Disease, 2003Co-Authors: Natalia A Peres, J P Agostini, L W TimmerAbstract:Alternaria alternata (Fr.) Keissler causes lesions on leaves, twigs, and fruit and reduces yield and fruit quality of many tangerines (Citrus reticulata) and their hybrids (2). Severe outbreaks of Alternaria Brown Spot were observed on ‘Murcott’ tangor (Citrus reticulata × Citrus sinensis) trees in southern Sao Paulo, southern Minas Gerais states in Brazil, and in Misiones and Corrientes provinces in Argentina. A single diseased ‘Fortune’ tangerine tree was observed in a grove in Misiones. On young leaves, Brown-to-black lesions often expanded to cover large parts of the leaf, causing abscission of young shoots and dieback of twigs. Lesions were often surrounded by yellow halos. On fruit, dark specks from 0.2 to 0.5 cm were observed, and severe infection caused premature fruit abscission. Isolations were made on potato dextrose agar (PDA) after surface sterilization of leaf and fruit tissues in 1.5% sodium hypochlorite for 1 min. Plates were incubated at 27°C in the dark for 1 week. Isolated colonies were...
Tobin L Peever - One of the best experts on this subject based on the ideXlab platform.
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identification of a novel phylogenetic lineage of alternaria alternata causing citrus Brown Spot in china
Fungal Biology, 2015Co-Authors: Feng Huang, Danni Nie, Jane E Stewart, Tobin L PeeverAbstract:Abstract Alternaria alternata sensu lato , casual agent of citrus Brown Spot, first identified in Yunnan province in 2010 and subsequently found in Zhejiang, Hunan, Guangdong provinces, Chongqing municipality andGuangxi autonomous region in China. During 2010–2012, 86 isolates were collected from diseased citrus, of which 85 % isolates were pathogenic to Ponkan tangerine. Phylogenetic analyses of Chinese and worldwide isolates using partial sequences of an endopolygalacturonase gene ( endoPG ) and combined dataset of endoPG and two anonymous loci (OPA1-3, OPA2-1) found that Chinese isolates fell into two of three previously described clades. One clade (‘clade 3’) contained isolates from Turkey and Israel, and the other clade (‘clade 1’) contained isolates from Florida, USA. None of the isolates from China fell into the last previously described clade (‘clade 2’). However, 24 isolates from Hunan, Guangdong and Guangxi fell into a fourth clade (‘clade 4’) not previously reported to be associated with citrus Brown Spot. This clade included multilocus haplotypes known to infect Japanese pear and strawberry. The observation that Chinese Brown Spot isolates fell into only two of three known worldwide lineages suggests that this fungus may not have co-evolved with its host in China but elsewhere in Southeast Asia and introduced to China.
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signatures of recombination in clonal lineages of the citrus Brown Spot pathogen alternaria alternata sensu lato
Phytopathology, 2013Co-Authors: Jane E Stewart, Kalyn Thomas, Christopher B Lawrence, Ha X Dang, Barry M Pryor, L M Timmer, Tobin L PeeverAbstract:Most Alternaria spp. are considered asexual but recent molecular evolution analyses of Alternaria mating-type genes show that the mating locus is under strong purifying selection, indicating a possible role in sexual reproduction. The objective of this study was to determine the mode of reproduction of an Alternaria alternata sensu lato population causing citrus Brown Spot in central Florida. Mating type of each isolate was determined, and isolates were sequenced at six putatively unlinked loci. Three genetically distinct subpopulations (SH1, SH4A, and SH4B) were identified using network and Bayesian population structure analyses. Results demonstrate that most subpopulations of A. alternata associated with citrus are clonal but some have the ability to extensively recombine through a cryptic sexual cycle or parasexual cycle. Although isolates were sampled in close physical proximity (≈2,500-m² area), we were able to reject a random mating model using multilocus gametic disequilibrium tests for two subpopulations, SH1 and SH4B, suggesting that these subpopulations were predominantly asexual. However, three recombination events were identified in SH1 and SH4B and localized to individuals of opposite mating type, possibly indicating meiotic recombination. In contrast, in the third subpopulation (SH4A), where only one mating type was present, extensive reticulation was evident in network analyses, and multilocus gametic disequilibrium tests were consistent with recombination. Recombination among isolates of the same mating type suggests that a nonmeiotic mechanism of recombination such as the parasexual cycle may be operating in this subpopulation. The level of gene flow detected among subpopulations does not appear to be sufficient to prevent differentiation, and perhaps future speciation, of these A. alternata subpopulations.
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first report of alternaria Brown Spot of citrus caused by alternaria alternata in peru
Plant Disease, 2006Co-Authors: J E Marin, Tobin L Peever, H S Fernandez, Natalia A Peres, M Andrew, L W TimmerAbstract:Alternaria Brown Spot, caused by Alternaria alternata (Fr.) Keissler, causes leaf, twig, and fruit lesions and reduces yield and fruit quality of many tangerines (Citrus reticulata Blanco) and their hybrids (3). In 2003, characteristic symptoms of Brown Spot were observed on young leaves and fruit of 'Minneola' tangelo in the Satipo Province of Peru. In 2004, the disease was discovered in the provinces of Chanchamayo, Leoncio Prado, and La Convencion in the Junin, Huanuco, and Cusco regions, respectively, as well as in the Apurimac and the Ene valleys. In 2005, it was confirmed in the province of Oxapampa in the Pasco Region. Brown-to-black lesions surrounded by yellow halos and veinal necrosis were observed on young leaves, often causing abscission of young shoots and twig dieback. Light Brown, circular lesions were observed on fruit, and when severe, resulted in premature abscission. Isolations from infected leaves and twigs were made on potato dextrose agar (PDA) with 10 μg/ml of benomyl. Colonies that developed after 5 days at 27°C were olive Brown-to-black and produced small, muriform, pigmented conidia typical of A. alternata. On PDA without benomyl, gray colonies with conidia typical of Colletotrichum gloeosporioides were recovered frequently. Inoculation of three detached young shoots of 'Minneola' by spraying with a suspension of 105 conidia/ml of A. alternata produced leaf and twig symptoms characteristic of the disease after 48 h and confirmed pathogenicity of three isolates. Symptoms were not observed on control leaves sprayed with water nor on an equal number of leaves inoculated with a suspension of 105 conidia/ml of C. gloeosporioides. Reisolation of A. alternata from diseased tissue fulfilled Koch's postulates. DNA was extracted from 17 isolates and a partial endopolygalacturonase gene was amplified and sequenced (2). Sequences of all 17 isolates were identical, and in BLAST searches of the NCBI database, the closest matches were A. alternata accession nos. AY295023.1, AY295022.1, and AY295021.1 with 100, 99.8, and 99.8% sequence similarity, respectively. Phylogenetic analyses revealed that all isolates from Peru clustered with Brown Spot isolates from Israel, Turkey, South Africa, and Australia (1). These results, along with morphological characterization and pathogenicity tests, confirm the identity of the fungus as the tangerine pathotype of A. alternata. The disease has significantly reduced yield and the commercial value of fruit and may be a limiting factor for the production of susceptible cultivars in those areas of Peru. References: (1) T. L. Peever et al. Phytopathology 92:794, 2002. (2) T. L. Peever et al. Mycologia 96:119, 2004, (3) L.W. Timmer et al. Pages 19-21 in: Compendium of Citrus Diseases. 2nd ed. L. W. Timmer et al eds. The American Phytopathological Society, St. Paul, MN, 2000.
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worldwide phylogeography of the citrus Brown Spot pathogen alternaria alternata
Phytopathology, 2002Co-Authors: Tobin L Peever, Kazuya Akimitsu, A M Ibanez, L W TimmerAbstract:ABSTRACT Sixty-five isolates of Alternaria alternata were sampled from Brown Spot lesions on tangerines and mandarins (Citrus reticulata) and tangerine × grapefruit (C. reticulata × C. paradisi) hybrids in the United States, Colombia, Australia, Turkey, South Africa, and Israel to investigate the worldwide phylogeography of the fungus. Genetic variation was scored at 15 putative random amplified polymorphic DNA (RAPD) loci and 465 bp of an endo-polygalacturonase (endo-PG) gene was sequenced for each isolate. Cluster analysis of RAPD genotypes revealed significant differentiation between United State and Colombia isolates and Turkey, South Africa, Israel, and Australia isolates. Sequencing of endo-PG revealed 21 variable sites when the outgroup A. gaisen (AK-toxin-producing pathogen of Japanese pear) was included and 13 variable sites among the sampled isolates. Nucleotide substitutions at 10 of 13 variable sites represented silent mutations when endo-PG was translated in frame. Eight distinct endo-PG hapl...
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environmental factors affecting the severity of alternaria Brown Spot of citrus and their potential use in timing fungicide applications
Plant Disease, 2000Co-Authors: L W Timmer, Tobin L Peever, A M Ibanez, H M Darhower, S E Zitko, P M BushongAbstract:Alternaria Brown Spot affects many tangerines and their hybrids, causing lesions on leaves, twigs, and fruit resulting in reduced yield and fruit quality. Field studies were conducted in a severely affected Minneola tangelo grove in central Florida from 1996 to 1998 to determine the environmental factors associated with infection of field trees and potted trap plants. Conidial production peaked following large flushes of new leaves, which were heavily infected. Most infections occurred during the summer rainy season, but trap plants became infected nearly every week of the year. When plants were exposed for 1-week periods, linear regression analysis indicated that disease severity on trap plants was positively related to the amount of rainfall, duration of leaf wetness, and average daily temperatures, and negatively related to the number of conidia trapped. Similar relationships occurred with trap plants exposed for 24-h periods on 141 different dates, except that temperature was not a significant factor. Nevertheless, these factors individually or combined in stepwise multiple regressions explained only a low percentage of the variability in disease severity with both weekly and daily trap plant sampling. When daily environmental data were categorized as: (i) rain versus no rain, (ii) 10 h leaf wetness duration, and (iii) average temperature 28°C, relationships to disease severity on trap plants were clearer. Disease severity on days with rain was nearly double that of days without rain, but considerable infection occurred on days with >10 h leaf wetness duration and no rain. Infection was greatest on days with temperatures of 20 to 28°C and slightly less at lower or higher temperatures. A point system, called the ALTER-RATER, was designed whereby each day would be assigned a severity value according to the prevailing environmental conditions. A fungicide application would be made after a predetermined number of points had accumulated. Simulated spray programs based on accumulation of 50, 75, 100, and 150 points from historical weather data at several locations indicated that from 8 to 15, 6 to 8, 5 to 6, or 3 to 4 sprays, respectively, would be needed depending on year and location in Florida. Such a weather-based control system could reduce the number of fungicide applications and improve control of Alternaria Brown Spot of tangerine.
Marina Collina - One of the best experts on this subject based on the ideXlab platform.
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genome sequence resource for stemphylium vesicarium causing Brown Spot disease of pear
Molecular Plant-microbe Interactions, 2019Co-Authors: Katia Gazzetti, Elena L Diaconu, Irene Maja Nanni, Alessandro Ciriani, Marina CollinaAbstract:Stemphylium vesicarium is the causal agent of several plant diseases as well Brown Spot of pear (BSP), which is one of the most economically important fungal diseases in European pear-production areas. In addition to the relevance of the economic impact, conidia spread widely from plant material infected by the pathogen can trigger respiratory allergy. Here, we report the first genome of a S. vesicarium strain, 173-1a13FI1M3, isolated from pear and sensitive to the mostly used fungicide classes currently authorized in Europe against BSP. The availability of this draft genome could represent a first important step in understanding the physiology and the infection mechanism of the pathogen. Furthermore, this contribution could be fundamental in order to design more effective and sustainable strategies to control the disease.
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Baseline sensitivity of Stemphylium vesicarium, the causal agent of pear Brown Spot, to boscalid
2009Co-Authors: Giulia Alberoni, Marina Collina, D. Cavallini, A. BrunelliAbstract:INTRODUCTION The control of Stemphylium vesicarium (Wallr.) Simm., the causal agent of pear Brown Spot, is a true concern for pear growers in Italy because many fungicide treatments are required from petal fall to fruit ripening (Ponti et al.,1996; Brunelli et al., 2004). The occurrence of resistance to dicarboximides in the early 1990’s (Brunelli et al., 1997) and to strobilurins in 2006 (Collina et al., 2007) complicated the control of this pathogen even more. The introduction in the field of new fungi-cides with different mechanisms of action is thus fundamental in order to enlarge the range of effective fungicides against pear Brown Spot and to reduce the risk of further resistances. At the end of the 2006 season boscalid was registered in Italy for pear. It belongs to the carboxamide-fungicide group and inhibits the respiratory chain acting on the enzyme succinate dehydrogenase in complex II (Stammler et al., 2007). This mode of action is different from that of both dicarboximide and strobilurin fungicides and it could be used in cases of field resistance to these compounds. Nevertheless, boscalid is considered by the FRAC to have a medium risk of resistance for its spe-cific target (www.frac.info). In order to evaluate the sensitivity of S. vesicarium to this fungicide, an in vitro assay was developed comparing different methods (on mycelial growth with differ-ent media and on conidial germination). Baseline sensitivity was then determined for isolates which have never been exposed to boscalid
Keisuke Kohmoto - One of the best experts on this subject based on the ideXlab platform.
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Purification and Biological Characterization of Host-Specific SV-Toxins from Stemphylium vesicarium Causing Brown Spot of European Pear.
Phytopathology, 1999Co-Authors: P. Singh, Motoichiro Kodama, Hiroshi Otani, R. Bugiani, P. Cavanni, Hiromitsu Nakajima, Keisuke KohmotoAbstract:ABSTRACT Culture filtrates of a pathogenic isolate (IT37) of Stemphylium vesicarium, causing Brown Spot of European pear, induced veinal necrosis only on pear leaves susceptible to the pathogen. Two host-specific toxins, SV-toxins I and II, were purified from culture filtrates of IT37 by successively using Amberlite XAD-2 resin adsorption, cellulose thin-layer chromatography, and high-performance liquid chromatography under three different sets of conditions. Susceptible cultivars showed veinal necrosis at a SV-toxin I concentration of 0.01 to 0.1 μg/ml, whereas resistant cultivars were insensitive to the toxin at 1,000 μg/ml. SV-toxins I and II caused a dose-dependent increase in electrolyte loss from susceptible leaf tissues. No increase in electrolyte loss was detected in leaf tissues from resistant cultivars. The results of physiological studies indicated that SV-toxins appear to have an early effect on plasma membranes of susceptible leaves. Spores of a nonpathogenic isolate induced necrotic lesions ...
Emilio Montesinos - One of the best experts on this subject based on the ideXlab platform.
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interaction of antifungal peptide bp15 with stemphylium vesicarium the causal agent of Brown Spot of pear
Fungal Biology, 2016Co-Authors: Mireia Puig, Concepcio Moragrega, Lidia Ruz, Emilio Montesinos, Claudia E Calderon, Francisco M Cazorla, I LlorenteAbstract:Peptide BP15 has shown antifungal activity against several plant pathogenic fungi, including Stemphylium vesicarium, the causal agent of Brown Spot of pear. BP15 inhibits the germination, growth and sporulation of S. vesicarium and displays post-infection activity by stopping fungal infection in pear leaves. In this work, live-cell imaging was undertaken to understand the antifungal mechanism of BP15. A double-staining method based on the combination of calcofluor white and SYTOX green coupled with epifluorescence microscopy was used to investigate fungal cell permeabilization and alterations in fungal growth induced by BP15. GFP-transformants of S. vesicarium were obtained and exposed to rhodamine-labelled BP15. Confocal laser microscopy provided evidence of peptide internalization by hyphae, resulting in fungal cell disorganization and death. S. vesicarium membrane permeabilization by BP15 was found to be peptide-concentration dependent. BP15 at MIC and sub-MIC concentrations (10 and 5 μM, respectively) inhibited S. vesicarium growth and produced morphological alterations to germ tubes, with slow and discontinuous compromise of fungal cell membranes. Fungal cell membrane disruption was immediately induced by BP15 at 100 μM, and this was accompanied by rapid peptide internalization by S. vesicarium hyphae. Peptide BP15 interacted with germ tubes and hyphae of S. vesicarium but not with conidial cells.
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an update on control of Brown Spot of pear
Trees-structure and Function, 2012Co-Authors: Isidre Llorente, Concepcio Moragrega, Lidia Ruz, Emilio MontesinosAbstract:Brown Spot of pear is a fungal disease producing high economical losses in several pear-growing areas in Europe. Fungicide applications during the growing period either at fixed schedule or delivered according to the BSPcast forecasting system are not enough to control the disease under favorable conditions. New strategies have been introduced to control the inoculum production using sanitation methods. These methods are based on combinations of leaf litter removal during winter and biological control agent applications during late winter, spring and summer. These practices reduce both the inoculum pressure and disease levels. Therefore, the resulting optimized disease management consists of a combination of sanitation methods applied during the whole year with chemical fungicides scheduled according to the BSPcast forecasting model during the vegetative period. It is expected that the control of Brown Spot could be further refined upon availability of rapid methods for inoculum potential analysis. However, this analysis is difficult due to the variability in pathogenicity within the pathogen population.
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control of Brown Spot of pear by reducing the overwintering inoculum through sanitation
European Journal of Plant Pathology, 2010Co-Authors: Isidre Llorente, Albert Vilardell, P Vilardell, Elisabetta Pattori, Riccardo Bugiani, Vittorio Rossi, Emilio MontesinosAbstract:Stemphylium vesicarium, the causal agent of Brown Spot of pear, overwinters in the leaf residues of pear and herbaceous plants of the orchard floor. Pseudothecia of the teleomorph, Pleospora allii, are formed on these residues where they produce ascospores. New methods were tested aimed at reducing this overwintering inoculum and increasing the efficacy of control of Brown Spot of pear. Sanitation methods were evaluated in nine trials in Girona (Spain) and Ferrara (Italy) over a 4-year period. The sanitation methods were leaf litter removal in December to February, and application of biological control agents (commercial formulates of Trichoderma spp.) to the orchard ground cover from February to May. Fungicides were also applied to the trees during the pear-growing season, scheduled according to the BSPcast model. The different methods were tested as stand-alone applications or in combination. All methods consistently reduced the disease incidence at harvest on fruit with an efficacy between 30 to 60% for leaf litter removal and more than 60% for the combination of leaf litter removal and biological control. Efficacy of sanitation alone (leaf litter removal and biological control) in reducing the Brown Spot level on fruit was similar in most of the trials to the efficacy obtained when fungicides were applied alone. However, integration of sanitation methods and fungicides did not improve the efficacy of disease control over the level provided by fungicides alone.
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Brown Spot of pear an emerging disease of economic importance in europe
Plant Disease, 2006Co-Authors: Isidre Llorente, Emilio MontesinosAbstract:Brown Spot of pear (BSP), a fungal disease caused by Stemphylium vesicarium (Wallr.) E. Simmons, is economically important in pear-production areas in Europe (Fig. 1) (4,14,18,31,42). The first outbreaks were reported in 1975 in the Emilia-Romagna region in Italy on Abate Fetel pear (31). In 1984, the disease was detected in Spain in the Catalunya region on Passe Crassane and Conference pears (42). Subsequently, it has been reported from France (1987), Portugal (1996), The Netherlands (1997), and Belgium (2002) (4,14,18,35). The relative importance of BSP has increased significantly over the past 10 years in Europe, and it is now considered of similar or even higher incidence than apple scab. Epidemics may be severe, and depending on the year and pear growing area, global losses may be between 1 and 10% of total production, in spite of the control measures applied. Levels of disease (5 to 10%) one year may be followed by up to 90% infected fruit in the next year (28,42).
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evaluation of bspcast disease warning system in reduced fungicide use programs for management of Brown Spot of pear
Plant Disease, 2000Co-Authors: Isidre Llorente, P Vilardell, Riccardo Bugiani, I Gherardi, Emilio MontesinosAbstract:A forecasting model (BSPcast) developed for prediction of Brown Spot (Stemphylium vesicarium) of pear was evaluated as an advisory system for reduced fungicide use in disease management programs. Eleven trials were performed during 1995, 1996, and 1997 in five orchards in two different climatic areas in Catalunya (Spain) and Emilia-Romagna (Italy). Values of 3-day cumulative daily infection risk (CR) provided by the model were used to determine risk periods during the growing season of pear and were taken as thresholds to schedule fungicide sprays. The fungicide application programs tested using the model consisted of guided schedules with CR action thresholds of 0.4, 0.5, or 0.6, and fixed sprays following a standard commercial schedule. In nine out of 10 trials, no significant differences were observed in disease incidence on fruit at harvest between the fixed-spray commercial schedule and guided sprays using thresholds of 0.4 or 0.5. The average savings in number of fungicide sprays applied using BSPcast compared with the fixed-spray schedule were 20 to 70% when using fungicides with a 15-day protection period (kresoxim-methyl or procymidone) and ranged from 20 to 50% when using a fungicide with a 7-day protection period (thiram).
