Navegando por Autor "Zambolim, L."
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Item Climate favourability to leaf rust in Conilon coffee(Australasian Plant Pathology, 2013-09) Capucho, A. S.; Zambolim, L.; Cabral, P. G. C.; E. T. Caixeta; Maciel-Zambolim, E.The Brazil is the second largest producer of Conilon coffee (Coffea canephora), being the state of Espírito Santo responsible for producing 9.7 million bags of Conilon coffee. The biology of Hemileia vastatrix, etiologic agent of leaf rust, the main disease of this culture, is not well understood under the environmental conditions of Espírito Santo, Brazil. This study determined the ideal temperature and leaf wetness ranges for in vitro germination and infection of leaf discs in this pathosystem. For this, regression analyses with differents temperature and leaf wetness ranges were performed. The results showed that a climate characterized by mild mean temperatures (between 21.6 °C and 23.6 °C) with foliar wetness associated with high relative humidity (>80 %) is the most favorable condition for the infection of Conilon coffee by H. vastatrix. The knowledge of the optimal temperature and moisture conditions for the infection can also be useful for developing systems to predict the occurrence of the disease in C. canephora from Brazil.Item Coffee bacterial diseases: a plethora of scientific opportunities(Plant Pathology, 2019-04) Badel, J. L.; Zambolim, L.Coffee is a very important crop for several tropical countries across different continents. The diseases bacterial halo blight (BHB), bacterial leaf spot (BLS), bacterial leaf blight (BLB) and coffee leaf scorch (CLS), caused by the bacterial pathogens Pseudomonas syringae pv. garcae (Psgc), P. syringae pv. tabaci (Psta), Pseudomonas cichorii (Pch) and Xylella fastidiosa subsp. pauca (Xfp), respectively, cause significant reductions in coffee production, although other minor bacterial diseases have also been reported in some countries. Little research progress has been made on aspects that are relevant for control and management of these diseases. In all cases, there is an urgent need to develop rapid and more reliable methods for early detection of the pathogens in order to minimize their negative impact on coffee production. Because of the high rate of intra- and intersubspecific recombination occurring in X. fastidiosa, a permanent revision of the detection methods is necessary. Greater efforts should be made to understand the genetic and virulence diversity of Psgc, Psta and Pch populations. Early studies reported the identification of potential sources of resistance against Psgc and Psta, but, to date, no resistance gene has been isolated. Little effort has been made to understand the biology and molecular mechanisms underlying the interaction between Coffea spp. and these pathogenic bacteria. This review discusses the recent progress on the molecular mechanisms used by these bacteria to cause diseases on other plant species, in order to provide a guideline for the establishment of future research programmes.Item The field resistance of potato cultivars to foliar late blight and its relationship with foliage maturity type and skin type in Brazil(Australasian Plant Pathology, 2012-03) Duarte, H. S. S.; Zambolim, L.; Mizubuti, E. S. G.; Pádua, J. G.; Ribeiro Júnior, J. I.; Nogueira Júnior, A. F.; Carmo, E. L.The use of resistant cultivars is the preferred control method for plant diseases. This approach is attractive owing to its high efficacy, low cost, and ease of implementation. This work aimed to assess the resistance of potato cultivars to foliar late blight (Phytophthora infestans) under different environmental conditions. It further aimed to assess the relationships between resistance to foliar late blight and foliage maturity type and between resistance to foliar late blight and the skin type of the potato. Three experiments were performed in two different regions of the state of Minas Gerais with different environmental conditions. The first and second experiments used 34 cultivars (treatments). The third experiment used 17 cultivars. The severity of foliar late blight in each plot was quantified every 2 days using a descriptive scale. The values of the epidemiological variables were then calculated. The proposed levels of resistance to foliar late blight were defined as: resistant (R), moderately resistant (MR), moderately susceptible (MS) and susceptible (S). The majority of potato cultivars were susceptible to foliar late blight. The resistance levels of some cultivars to foliar late blight used in these experiments changed according to the pathogen population and environmental conditions. The cultivars with the highest levels of resistance to foliar late blight (resistant and moderately resistant) were later maturity. Most cultivars that have been classified as moderately susceptible or susceptible were earlier maturity. In general, cultivars that are more resistant to foliar late blight had a rougher skin, whereas the skins of the more susceptible cultivars had smoother.Item The Híbrido de Timor germplasm: identification of molecular diversity and resistance sources to coffee berry disease and leaf rust(Euphytica, 2018-08-07) Silva, R. A.; Zambolim, L.; Castro, I. S. L.; Rodrigues, H. S.; Cruz, C. D.; Caixeta, E. T.The main phytosanitary problems affecting global coffee production are the fungal diseases known as rust, caused by Hemileia vastatrix Berkeley and Broome, and coffee berry disease (CBD), induced by Colletotrichum kahawae Waller and Bridge. The main disease control strategy is the use of resistant coffee cultivars. Híbrido de Timor is the most important source of resistant varieties used in breeding programs worldwide. The objective of this work was to characterize the diversity and disease resistance of 152 HdT genotypes from the germplasm collection at the Universidade Federal de Viçosa (UFV). Accessions were phenotyped with H. vastatrix races II and XXXIII. Molecular analysis was carried out with 29 random microsatellite markers or single sequence repeats (SSRs), and two SSRs associated with the CBD resistance gene Ck-1. All accessions in the germplasm collection were resistant to H. vastatrix race II, and 141 were resistant to H. vastatrix race XXXIII. Based on the presence of markers, there were 106 accessions containing the CBD resistance gene Ck-1. In the diversity study, the 152 accessions clustered into 21 different groups. A unique molecular profile (fingerprint) was determined for each individual, using 52 alleles from 22 SSR markers. The HdT germplasm of UFV was highly diverse, and included 99 accessions with multiple disease resistance genes, including the CBD resistance gene Ck-1, and others conferring resistance to H. vastatrix races II and XXXIII.Item Influence of leaf position that correspond to whole plant severity and diagrammatic scale for white spot of corn(Crop Protection, 2010-09) Capucho, A. S.; Zambolim, L.; Duarte, H. S. S.; Parreira, D. F.; Ferreira, P. A.; Lanza, F. E.; Costa, R. V.; Casela, C. R.; Cota, L. V.The main objective of this research is to determine the influence of leaf position on corn plants with white spot caused by Pantoea ananatis, which better represents the infection on the whole plant. A diagrammatic scale to quantify the severity of the disease was elaborated and validated. For scale elaboration, the minimal and maximal limits of the disease severity observed in the field were considered, and intermediate levels followed logarithmic increments according to the Weber–Fechner stimulation law. The scale has nine classes: 0.1, 1, 2, 4, 8, 16, 24, 32 and 64%. For scale evaluation, a severity evaluation for white spot was performed by 10 raters with no experience in disease evaluation. Initially, severity estimation was performed without a scale for 41 leaves with different levels of severity. Afterward, the same raters used the proposed diagrammatic scale. Through linear regression to compare the actual and estimate severity values, the raters’ accuracy and precision were analyzed. Satisfactory accuracy and precision were achieved when estimation was performed with a diagrammatic scale. To determine the best leaf disease severity evaluation, correlation and regression analyses were performed with 25 plants of five genotypes, for a total of 284 leaves analyzed. Results analysis leads us to conclude that the severity of white spot on corn plants significantly correlates with the disease mean severity of leaves 0 and -1, i.e., a leaf of the corn ear and the one immediately below it. This scale provided good levels of accuracy and precision (a mean R2 of 94%), with errors concentrating around 10%. Raters presented increased reproducibility (R2 > 90% in 82% of cases) of severity estimates. The proposed diagrammatic scale is considered adequate to estimate the severity of white spot in corn for germplasm evaluations, for epidemiological studies and for evaluation of control strategies for this disease.Item Insecticide use and organophosphate resistance in the coffee leaf miner Leucoptera coffeella (Lepidoptera: Lyonetiidae)(Bulletin of Entomological Research, 2007-03-01) Fragoso, D. B.; Guedes, R. N. C.; Picanço, M. C.; Zambolim, L.Increasing rates of insecticide use against the coffee leaf miner Leucoptera coffeella (Guérin-Méneville) and field reports on insecticide resistance led to an investigation of the possible occurrence of resistance of this species to some of the oldest insecticides used against it in Brazil: chlorpyrifos, disulfoton, ethion and methyl parathion. Insect populations were collected from ten sites in the state of Minas Gerais, Brazil and these populations were subjected to discriminating concentrations established from insecticide LC 99 s estimated for a susceptible standard population. Eight of the field collected populations showed resistance to disulfoton, five showed resistance to ethion, four showed resistance to methyl parathion, and one showed resistance to chlorpyrifos. The frequency of resistant individuals in each population ranged from 10 to 93% for disulfoton, 53 to 75% for ethion, 23 to 76% for methyl parathion, and the frequency of resistant individuals in the chlorpyrifos resistant population was 35%. A higher requency of individuals resistant to chlorpyrifos, disulfoton and ethion was associated with greater use of insecticides, especially other organophosphates. This finding suggests that cross-selection, mainly between organophosphates, played a major role in the evolution of insecticide resistance in Brazilian populations of L. coffeella. Results from insecticide bioassays with synergists (diethyl maleate, piperonyl butoxide and triphenyl phosphate) suggested that cytochrome P450 dependent monooxygenases may play a major role in resistance with minor involvement of esterases and glutathione S-transferases.Item Persistência do fungicida triadimenol em solos(Revista Brasileira de Ciência do Solo, 1998-04) Albuquerque, M. A.; Schaefer, C. E. R.; Loures, E. G.; Zambolim, L.O grau de persistência do fungicida triadimenol, que é utilizado intensamente no controle da ferrugem do cafeeiro, foi avaliado em amostras de duas classes de solo, Podzólico Vermelho-Amarelo câmbico (PV) e Latossolo Vermelho-Amarelo variação Una (LU) da região de Viçosa, MG, com e sem adição de composto orgânico. Utilizou-se a técnica de bioautografia em camada fina. O triadimenol foi adicionado a 375 mg kg-1 de ingrediente ativo de solo, e as extrações dos resíduos fungitóxicos foram feitas 35, 70 e 115 dias após a incorporação aos solos, mantendo-se os tratamentos em condições de laboratório. A adição de composto orgânico não provocou variação significativa na degradação de triadimenol nos solos. Houve diferenças entre os solos na cinética de degradação do triadimenol, tendo no Podzólico ocorrido maiores taxas de degradação, possivelmente pela maior fertilidade natural, retenção de água e propriedades físicas e condições hídricas mais favoráveis à degradação microbiana. Nas condições do presente estudo e pela taxa de degradação verificada, o triadimenol pode ser considerado moderadamente persistente.Item Photosynthetic and antioxidative alterations in coffee leaves caused by epoxiconazole and pyraclostrobin sprays and Hemileia vastatrix infection(Pesticide Biochemistry and Physiology, 2015-02-11) Honorato Júnior, J.; Zambolim, L.; Aucique-Pérez, C.E.; Resende, R.S.; Rodrigues, F.A.Coffee leaf rust (CLR), caused by Hemileia vastatrix, is a major disease affecting coffee production worldwide. In this study, an in-depth analysis of the photosynthetic performance of coffee leaves challenged or not with H. vastatrix and sprayed with either epoxiconazole (EPO) or pyraclostrobin (PYR) was performed by combining chlorophyll a fluorescence images, photosynthetic pigment pools and the activities of chitinase (CHI), β-1,3-glucanase (GLU), peroxidase (POX) and catalase (CAT). The CLR severity was higher in the control plants, but reduced in plants sprayed with both PYR and EPO. Also, the CLR severity was reduced in plants sprayed with PYR compared with plants sprayed with EPO. Plants sprayed with either EPO or PYR showed maximal photosystem II quantum efficiency (Fv/Fm) values ranging from 0.78 to 0.80, which were quite similar to those obtained with inoculated plants (values ranging from 0.74 to 0.77). The decreases in the Fv/Fm ratio values and parallel increases in the F0 values in the inoculated plants, which were not observed in the control plants (sprayed with water) and were confirmed by images of the initial fluorescence (F0) and Fv/Fm parameters in the regions of the leaf tissue containing pustules and in the asymptomatic leaf tissue, indicated that photosynthesis was negatively impacted. When effective photosystem II quantum yield (Y(II)) values approached zero with a high photosynthetic photon flux density, high values of quantum yield of regulated energy dissipation (Y(NPQ)) in association with a high carotenoid concentration were noted in the inoculated plants sprayed either with PYR or EPO. The increased CLR severity in inoculated plants in contrast to inoculated plants sprayed with either PYR or EPO was associated with greater POX activity and a reduced photosynthetic pigment concentration. POX and CAT activities were increased in inoculated plants sprayed with either EPO or PYR when compared with control plants. CHI and GLU activities were maintained at high levels in the leaves of inoculated plants, regardless of the fungicide sprayed, indicating that CHI and GLU are less important for coffee resistance against CLR. The results of the present study clearly demonstrated that plants sprayed with either EPO or PYR showed milder CLR symptoms with adequate photosynthetic performance and optimal conditioning of their antioxidant systems.Item The population structure of Hemileia vastatrix in Brazil inferred from AFLP(Australasian Plant Pathology, 2013-09) Maia, T. A.; Caixeta, E. T.; Mizubuti, E. S. G.; Zambolim, L.; Maciel-Zambolim, E.Efforts to obtain durable resistant cultivars to coffee leaf rust have a long history of disappointment because of the lack of information on the Hemileia vastatrix evolutionary potential. In this study, the AFLP marker was used to analyze the genetic structure of a field population of H. vastatrix from different coffee genotypes cultivated in a wide geographic region of Brazil’s main production areas. A total of 91 isolates were sampled from genotypes of Coffea arabica, C. canephora and Híbrido de Timor/Icatu derivatives. Each isolate exhibited unique multilocus AFLP genotypes with no identical isolates obtained from the same geographical and host origins. This finding was corroborated by a small correlation between genetic similarity and geographic distance (R xy = 0.31, P = 0.23). The analyses showed a low genetic differentiation (G ST = 0.026) between the populations defined by a host and AMOVA analysis, most of the genetic variance (99.56 %) was attributed to differences within populations. In addition, based on the index of association (IA), the random mating possibility was not rejected (IA = 0.225, P = 0.123) for the population of H. vastatrix derived from C. canephora. This result suggested that H. vastatrix in Brazil behaves as a large undifferentiated population with a high level of genotypic diversity that is unstructured with regard to its geographic and host origins.