Browsing by Author "Latorre, BA"

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    Characterization of Botrytis cinerea from table grapes in Chile using RAPD-PCR
    (AMER PHYTOPATHOLOGICAL SOC, 1999) Thompson, JR; Latorre, BA
    Random amplified polymorphic DNA (RAPD) analysis was performed on 29 isolates of Botrytis cinerea Pers. ex Fr. isolated from table grapes (Vitis vinifera L.) and other crops in Chile with 29 decaprimers. No single primer was found to differentiate either the host or the geographical origin of each of the B. cinerea isolates tested. The DNA profiles obtained, particularly with primers OPA4 and OPA11, distinguished isolates of B. cinerea from other epiphyte fungi found on table grapes, including Alternaria alternata, Aspergillus niger; Cladosporium herbarum, Epiccocum nigrum; Rhizopus stolonifer, a Penicillium sp., and yeasts (Cryptococcus laurentii, Rhodotorula glutinis, and Saccharomyces cerevisiae). Regardless of host origin, primers OPA4 and OPA11 amplified a strong fragment of 1.2 kilobases (kb) and two fragments of 1.10 and 0.7 kb, respectively. These DNA fragments were obtained even when only one conidium of B. cinerea was in the test sample. Three main groups were clearly defined based on the genetic similarities found in additional RAPD analysis with 19 arbitrary decaprimers and 15 selected isolates of B. cinerea. The overall similarity coefficients (SC) between the groups obtained ranged from 0.326 to 0.891. Interestingly, all isolates from table grapes were included in group I(SC: 0.761 to 0.826), isolates from apple and tomato were in group II (SC: 0.739 to 0.848), while isolates from blueberry were either in group I (SC: 0.804) or III (SC: 0.673). Consequently, the genetic variability determined by RAPD analysis among these B. cinerea isolates suggested a possible host:pathogen relationship. However, further research is needed to clarify its pathological significance.
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    Crown and root rots of table grapes caused by Phytophthora spp. in Chile
    (BUNDESANSTALT ZUCHTUNGS FORSCHUNG KULTURPFLANZEN, 1997) Latorre, BA; Wilcox, WF; Banados, MP
    Phytophthora crown and root rot of grapevine (Vitis vinifera L.) occurs frequently in Chile, where grapes are cultivated on their own roots. P. cinnamomi, P. cryptogea, and P. drechsleri were isolated from diseased root or crown tissue of the table grape cvs Flame Seedless, Italia, Red Globe, and Thompson Seedless with P. cryptogea being the most frequently isolated species. These pathogens were identified on the basis of standard morphological and cultural features and were compared by SDS-PAGE profiles of mycelial proteins. All isolates were pathogenic on 1-year-old cane segments and 1-year-old rooted grapevines of cvs Thompson Seedless and Red Globe. The latter cultivar was more susceptible than Thompson Seedless. P. cinnamomi and P. cryptogea have been associated with root rot of grapevines elsewhere, but this is the first report of P. drechsleri as a pathogen of grapevines and the first report of Phytophthora spp. affecting table grapes in Chile.
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    Effectiveness of conidia of Trichoderma harzianum produced by liquid fermentation against Botrytis bunch rot of table grape in Chile
    (ELSEVIER SCI LTD, 1997) Latorre, BA; Agosin, E; SanMartin, R; Vasquez, GS
    Over 100 isolates of Trichoderma harzianum Rifai were obtained from soil samples and from the phylloplane of kiwifruit (Actinidia chinensis Planchon), grape (Vitis vinifera), orange (Citrus sinensis (L.) Osbeck), eucalyptus (Eucalyptus globulus Labill.), and apricot (Prunus armeniaca L.) in Chile. A subsample of 48 isolates were tested and found to be antagonistic to Botrytis cinerea Pers. ex Fr. on apple fruits. Isolate S10B from soil in Chile provided similar control of Botrytis bunch rot under field conditions to reference isolate P1 (ATCC 74058) and T39 (Trichodex 25 WP). However, field trials conducted during four growing seasons (1992-1995) with preparations of conidia of formulated or non-formulated T. harzianum P1 provided only partial control of Botrytis bunch rot of 'Thomson Seedless' table grape. Disease incidence was significantly different (p < 0.05) from untreated controls, but equal to or less than the control achieved with vinclozolin (Ronilan 50 WP, 1.5 kg ha(-1)) and similar to captan (Captan 80 WP, 4 kg ha(-1)). This level of control is insufficient considering that tolerance for B. cinerea is very low (< 0.5%) on table grapes. Nevertheless, the antagonistic activity of T. harzianum may be effective if it is integrated with other control practices, and may result in acceptable levels of disease control with reduced levels of pesticide use. (C) 1997 Elsevier Science Ltd.
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    Identities and geographic distributions of Phytophthora spp. causing root rot of red raspberry in Chile
    (AMER PHYTOPATHOLOGICAL SOC, 2002) Wilcox, WF; Latorre, BA
    Five identified and two unidentified Phytophthora spp. were isolated from diseased roots of dead or declining red raspberry (Rubus idaeus L.) plants sampled from 18 plantations along a >1,000-km north-south axis in Chile. The array of Phytophthora spp. isolated was strongly associated with geographical location. P. fragariae var. rubi was recovered from 75 and 60% of the plantations in the southern (40degrees16' to 40degrees53' S latitude) and central (34degrees35', to 37degrees23' S latitude) production sectors, respectively, but was not recovered from any plantation in the northern sector (32degrees43' to 33degrees45' S latitude). Similarly, P. megasperma and P. gonopodyides were recovered from multiple plantations in the southern and central sectors but were not recovered in the northern sector. In contrast, R cryptogea was recovered from 80% of the plantations in both the northern and central sectors but not from any plantation in the south, whereas P citricola was isolated from diseased plants in all sectors. In subsequent pathogenicity trials, P. citricola, P. cryptogea, and an unidentified Phytophthora sp. were equally and highly virulent on 'Heritage' red raspberry in each of three greenhouse experiments. The other species were less virulent in the experiment when soil temperatures were highest (mean weekly maximum = 27.5degreesC) relative to the other two experiments when temperatures were more moderate (mean weekly maxima of 19.9 and 23.7degreesC). Isolates identified as R cryptogea were very similar to R cryptogea isolates recovered previously from kiwi fruit in Chile and from deciduous fruit trees in California with respect to morphological characters and electrophoretic banding patterns of soluble mycelial proteins. Using the same criteria, isolates identified as R gonopodyides were very similar to isolates recovered earlier from deciduous fruit crops in New York, which previously were identified as R cryptogea sensu lato but are hereby reclassified as P. gonopodyides.
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    Modified atmosphere packaging using chlorine gas generators to prevent Botrytis cinerea on table grapes
    (ELSEVIER SCIENCE BV, 1999) Zoffoli, JP; Latorre, BA; Rodriguez, EJ; Aldunce, P
    Decay, caused by Botrytis cinerea Pers. ex Fr., is the major sanitation problem of Chilean table grapes shipped to the USA, Europe and Asia. Postharvest treatments are compulsory to avoid significant losses. At present, this is achieved through the inclusion of one sulfur dioxide (SO2)-generator pad per box in combination with storage at 0 degrees C. Chlorine gas (Cl-2) produced by a salt mixture and combined with 25 days of storage at 0 degrees C significantly (P < 0.05) reduced Botrytis decay in artificially inoculated table grapes cvs. 'Flame Seedless','Thompson Seedless', and 'Ribier'. Infections by conidia or mycelium of B. cinerea, were suppressed for up to 45 days in cool storage, providing a similar degree of protection to that of one SO2-generator pad. Naturally infected grapes, from a commercial harvest developed significantly less Botrytis decay than controls upon arrival in the USA after 25 days transportation. No deleterious effect due to chlorine gas generation was observed. These results suggest that this is a sound alternative to SO2 for postharvest control of decay in table grapes. (C) 1999 Elsevier Science B.V. All rights reserved.
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    Occurrence of resistant strains of Botrytis cinerea to anilinopyrimidine fungicides in table grapes in Chile
    (ELSEVIER SCI LTD, 2002) Latorre, BA; Spadaro, I; Rioja, ME
    Effort to control gray mold caused by Botrytis cinerea failed in a table grapevine (Vitis vinifera) vineyard near Santiago, Chile where cyprodinil (Vangard 50 WP), a new fungicide of the anilinopyrimidine group, had been applied alone up to four times per year during two growing seasons. A relatively high frequency (38.5%) of resistant isolates of R cinerea (EC50 for mycelial growth inhibition varied from. 2.9 to 4.84 mug ml(-1)) may explain the partial loss of field control efficacy obtained. Resistance was correlated. with a complete loss of in vivo sensitivity to cyprodinil. Resistant. isolates of B. cinerea showed cross resistance to the anilinopyrimidines fungicides mepanipyrim and pyrimethanil. Cyprodinil partially impaired conidia germination and differentially affected conidial germination of resistant and sensitive isolates. Significant differences (p < 0.05) in growth rate, sclerotia production and osmotic sensitivity were found among isolates of B. cinerea, but no correlation could be drawn between these biological differences and resistance or sensitivity. This indicates a disruptive selection characteristic of monogenic resistance. Thus, strategies were implemented to avoid the further development and spread of resistance in B. cinerea to the anilinopyrimidine fungicides. To our knowledge this constitutes the first mention of resistance in B. cinema populations to anilinopyrimidine fungicides in South America. (C) 2002 Elsevier Science Ltd. All rights reserved.
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    Phytophthora species associated with crown and root rot of apple in Chile
    (AMER PHYTOPATHOLOGICAL SOC, 2001) Latorre, BA; Rioja, ME; Wilcox, WF
    Phytophthora cactorum, P. cryptogea, P. gonapodyides, and P. megasperma were isolated from necrotic root and crown tissues or the rhizospheres of apple trees exhibiting typical symptoms of Phytophthora root and crown rot in the Central Valley of Chile. Representative isolates of all four species were pathogenic on a variety of apple rootstocks and scions in trials conducted on excised shoots and 1-year-old MM.106 rootstock grown for 4 months in infested potting medium. P. cactorum was the most frequently isolated species and the most virulent in pot tests, although a significant Phytophthora sp.-apple genotype interaction was observed. This is the first report of any species other than P. cactorum causing root and crown rot of apple trees in Chile.
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    The effect of preharvest fungicide and postharvest sulfur dioxide use on postharvest decay of table grapes caused by Penicillium expansum
    (ELSEVIER, 2005) Franck, J; Latorre, BA; Torres, R; Zoffoh, JP
    Postharvest diseases are the most important factors that limit commercial export of Chilean table grapes (Vitis vinifera). In recent years, blue mold decay caused by Penicillium expansum has frequently appeared on Red Globe (RG) grapes after long term (>60 days) cold storage, causing important economical losses. Isolates of P. expansum obtained from grapes were pathogenic and the susceptibility of grape berries cvs. RG and Thompson Seedless (TS) increased markedly as the soluble solids concentration (SSC) increased from approximately 4-20%. However, higher SSC appeared to limit blue mold development on RG grapes. On detached berries inoculated with P. expansum, fludioxonil (200 mg L-1) or cyprodinil + fludioxonil (250 + 170 mg L-1) completely controlled it, while cyprodinil (330 mg L-1) reduced it by 87.6%. On detached berries inoculated with B. cinerea, applications of cyprodinil (330 mg L-1) or cyprodinil + fludioxonil (250 + 170 mg L-1) completely controlled it, while fludioxonil (200 mg L-1) reduced it by 37.5%. Fenhexamid (400 mg L-1) was 100% effective against B. cinerea but ineffective against P. expansum. After vineyard applications of an aqueous spray or dust of cyprodinil + fludioxonil (375 + 250 g La. ha(-1)) 24 h before harvest, significant (P < 0.05) reductions in postharvest decay were obtained during 30 days storage of the grapes at 0 degrees C. The postharvest incidence of P. expansion and B. cinerea was effectively reduced on packaged RG treated with either 0.85 g kg(-1) Na2S2O5 (G1, SO2-generating pad) or 1.22 g Na2S2O5 kg(-1) (G2, SO2-generating pads). Similar results were obtained on Flame Seedless (FS) and TS grapes using SO2-generating pads G1 and G3 (1.22 g kg(-1) Na2S2O5). These SO2-generating pads were placed inside a polyethylene bag with either 0.3 or 2% vented area. Regardless of the proportion of vented area, the effect of SO2-generating pads lasted for over 45 days. There were no significant differences between SO2-generating pads to control R expansum; even on RG with treatment G2 where a higher content Na2S2O5 per box was attained compared with G1. Otherwise G2 was considerably better than G1 to control B. cinerea on RG table grapes stored for 90 and 120 days. Berry injuries were considerably higher when the G2 SO2-generating pad was used but were reduced when the fruit was packaged in a more ventilated bag (2% vented area). Our results demonstrated that both preharvest fungicide applications and SO2, applied as SO2-generating pads, effectively reduced decay of table grapes caused by R expansum and B. cinerea in long term cold storage. (C) 2005 Elsevier B.V. All rights reserved.
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    The effect of temperature on infection and a warning system for pear blossom blast caused by Pseudomonas syringae pv. syringae
    (ELSEVIER SCI LTD, 2002) Latorre, BA; Rioja, ME; Lillo, C
    Blossom blast caused by Pseudomonas syringae pv. syringae van Hall, is a major disease of pears (Pyrus spp.) in Chile. Freezing temperatures may predispose pears to infection, however, our results demonstrated that blossom blast infection might occur in the absence of frosts, at temperature higher than 5degreesC, provided that the appropriate inoculum concentration, moisture levels and the susceptible bloom stages were available. Regardless of the flower bud stage development, blossom blast was lowest at 5degreesC and highest at 20degreesC. The first symptoms appeared after 2-3 days at 20degreesC, and were delayed 2 days at 5 C. A significant and positive linear regression best explained the relationship between disease incidence and temperature. A warning system, based on temperature and free moisture conditions, was developed and found to be useful for prediction of blossom blast infection in the field. Antibiotic treatments applied after each warning significantly (p<0.05) reduced blossom blast on Packham's Triumph pears. (C) 2002 Elsevier Science Ltd. All rights reserved.