scholarly journals Climatic drivers of Verticillium dahliae occurrence in Mediterranean olive-growing areas of southern Spain

2020 ◽  
Author(s):  
Juan Miguel Requena-Mullor ◽  
Jose Manuel García-Garrido ◽  
Pedro Antonio García ◽  
Estefanía Rodríguez
Keyword(s):  
Verticillium Dahliae ◽  
Climatic Factors ◽  
Irrigation Management ◽  
Temperature Oscillation ◽  
Landscape Scale ◽  
Southern Spain ◽  
Climatic Variables ◽  
Information Theoretic ◽  
Climatic Drivers ◽  
Olive Trees

AbstractVerticillium wilt, caused by the soil-borne fungus Verticillium dahliae, is one of the most harmful diseases in Mediterranean olive-growing areas. Although, the effects of both soil temperature and moisture on V. dahliae are well known, there is scant knowledge about what climatic drivers affect the occurrence of the pathogen on a landscape scale. Here, we investigate what climatic drivers determine V. dahliae occurrence in olive-growing areas in southern Spain. In order to bridge this gap in knowledge, a landscape-scale field survey was carried out to collect data on the occurrence of V. dahliae in 779 olive groves in Granada province. Forty models based on competing combinations of climatic variables were fitted and evaluated using information-theoretic methods. A model that included a multiplicative combination of seasonal and extreme climatic variables was found to be the most viable one. Isothermality and the seasonal distribution of precipitation were the most important variables influencing the occurrence of the pathogen. The isothermal effect was in turn modulated by the seasonality of rainfall, and this became less negative as seasonality increases. Thus, V. dahliae occurs more frequently in olive-growing areas where the day-night temperature oscillation is lower than the summer-winter one. We also found that irrigation reduced the influence of isothermality on occurrence. Our results demonstrate that long-term “sophisticated” climatic factors rather than “primary” variables, such as annual trends, can better explain the spatial patterns of V. dahliae occurrence in Mediterranean, southern Spain. One important implication of our study is that appropriate irrigation management, when temperature oscillation approaches optimal conditions for V. dahliae to thrive, may reduce the appearance of symptoms in olive trees.

scholarly journals Climatic drivers of Verticillium dahliae occurrence in Mediterranean olive-growing areas of southern Spain

PLoS ONE ◽  
2020 ◽  
Vol 15 (12) ◽  
pp. e0232648
Author(s):  
Juan M. Requena-Mullor ◽  
Jose Manuel García-Garrido ◽  
Pedro Antonio García ◽  
Estefanía Rodríguez
Keyword(s):  
Verticillium Dahliae ◽  
Large Scale ◽  
Climatic Factors ◽  
Irrigation Management ◽  
Temperature Oscillation ◽  
Southern Spain ◽  
Climatic Variables ◽  
Large Scale Field ◽  
Climatic Drivers ◽  
Olive Trees

Verticillium wilt, caused by the soil-borne fungus Verticillium dahliae, is one of the most harmful diseases in Mediterranean olive-growing areas. Although, the effects of both soil temperature and moisture on V. dahliae are well known, there is scant knowledge about what climatic drivers affect the occurrence of the pathogen on a large scale. Here, we investigate what climatic drivers determine V. dahliae occurrence in olive-growing areas in southern Spain. In order to bridge this gap in knowledge, a large-scale field survey was carried out to collect data on the occurrence of V. dahliae in 779 olive groves in Granada province. Forty models based on competing combinations of climatic variables were fitted and evaluated using information-theoretic methods. A model that included a multiplicative combination of seasonal and extreme climatic variables was found to be the most viable one. Isothermality and the seasonal distribution of precipitation were the most important variables influencing the occurrence of the pathogen. The isothermal effect was in turn modulated by the seasonality of rainfall, and this became less negative as seasonality increases. Thus, V. dahliae occurs more frequently in olive-growing areas where the day-night temperature oscillation is lower than the summer-winter one. We also found that irrigation reduced the influence of isothermality on occurrence. Our results demonstrate that long-term compound climatic factors rather than “primary” variables, such as annual trends, can better explain the spatial patterns of V. dahliae occurrence in Mediterranean, southern Spain. One important implication of our study is that appropriate irrigation management, when temperature oscillation approaches optimal conditions for V. dahliae to thrive, may reduce the appearance of symptoms in olive trees.

scholarly journals Region-Wide Analysis of Genetic Diversity in Verticillium dahliae Populations Infecting Olive in Southern Spain and Agricultural Factors Influencing the Distribution and Prevalence of Vegetative Compatibility Groups and Pathotypes

2011 ◽  
Vol 101 (3) ◽  
pp. 304-315 ◽  
Author(s):  
Rafael M. Jiménez-Díaz ◽  
Concepción Olivares-García ◽  
Blanca B. Landa ◽  
María del Mar Jiménez-Gasco ◽  
Juan A. Navas-Cortés
Keyword(s):  
Genetic Diversity ◽  
Verticillium Dahliae ◽  
Irrigation Management ◽  
Water Source ◽  
Vegetative Compatibility ◽  
Southern Spain ◽  
Vegetative Compatibility Groups ◽  
Discriminant Model ◽  
Olive Trees ◽  
Log Linear

Severity of Verticillium wilt in olive trees in Andalusia, southern Spain is associated with the spread of a highly virulent, defoliating (D) Verticillium dahliae pathotype of vegetative compatibility group 1A (VCG1A) but the extent of this spread and the diversity of the pathogen population have never been documented. VCG typing of 637 V. dahliae isolates from 433 trees in 65 orchards from five olive-growing provinces in Andalusia indicated that 78.1% were of VCG1A, 19.8% of VCG2A, 0.6% of VCG2B, 1.4% of VCG4B, and one isolate was heterokaryon self-incompatible. A single VCG prevailed among isolates within most orchards but two and three VCGs were identified in 12 and 3 orchards, respectively, with VCG1A+VCG2A occurring in 10 orchards. VCG1A was the predominant VCG in the three most important olive-growing provinces, and was almost as prevalent as VCG2A in another one. Molecular pathotyping of the 637 isolates using specific polymerase chain reaction assays indicated that VCG1A isolates were of the D pathotype whereas isolates of VCG2A, -2B, and -4B were of the less virulent nondefoliating (ND) pathotype. The pathotype of isolates correlated with the disease syndrome affecting sampled trees. Only three (seq1, seq2, and seq4) of the seven known sequences of the V. dahliae-specific 539- or 523-bp amplicon were identified among the 637 isolates. Distribution and prevalence of VCGs and seq sequences among orchards indicated that genetic diversity within olive V. dahliae in Andalusia is higher in provinces where VCG1A is not prevalent. Log-linear analysis revealed that irrigation management, source of irrigation water, source of planting stock, and cropping history of soil were significantly associated with the prevalence of VCG1A compared with that of VCG2A. Multivariate analyses using a selected set of agricultural factors as variables allowed development of a discriminant model for predicting the occurrence of D and ND pathotypes in the area of the study. Blind tests using this model correctly indentified the V. dahliae pathotype occurring in an orchard. The widespread occurrence and high prevalence of VCG1A/D pathotype in Andalusia have strong implications for the management of the disease.

scholarly journals Provenance Trials of the Mexican Spruces in Nursery Conditions: Three Species Endangered by Climatic Variation

2020 ◽  
Vol 3 (1) ◽  
pp. 12
Author(s):  
José Marcos Torres-Valverde ◽  
José Ciro Hernández-Díaz ◽  
Artemio Carrillo-Parra ◽  
Eduardo Mendoza-Maya ◽  
Christian Wehenkel
Keyword(s):  
Cluster Analysis ◽  
Genetic Differentiation ◽  
Local Adaptation ◽  
Quantitative Traits ◽  
Climatic Factors ◽  
Climatic Variation ◽  
Climatic Variables ◽  
Provenance Trials ◽  
Survival And Growth ◽  
Picea Species

The three Mexican spruces’ distributions are fragmented, which could lead to phenological, morphological and genetic differentiation, partially caused by local adaptation. In this study, we examined the effect that climatic variables had on the survival and growth of 5641 Picea seedlings, coming from eight seed provenances of three species and produced in identical nursery conditions. The respective responses of each species and provenance can be considered as a proxy of the genetic differentiation and adaptation of each population. A cluster analysis revealed: (i) significant differences in genetic quantitative traits among the three Picea species and (ii) significant correlations between genetic quantitative traits and climatic factors.

scholarly journals High Susceptibility of Olive Cultivar FS-17 to Alternaria alternata in Southern Spain

Plant Disease ◽  
2008 ◽  
Vol 92 (8) ◽  
pp. 1252-1252 ◽  
Author(s):  
J. Moral ◽  
R. De la Rosa ◽  
L. León ◽  
D. Barranco ◽  
T. J. Michailides ◽  
...  
Keyword(s):  
Alternaria Alternata ◽  
Disease Incidence ◽  
Southern Spain ◽  
Fruit Rot ◽  
Planting Density ◽  
High Susceptibility ◽  
Olive Cultivar ◽  
White Skin ◽  
Olive Cultivars ◽  
Olive Trees

Traditional olive orchards in Spain have been planted at a density of 70 to 80 trees per ha with three trunks per tree. During the last decade, the hedgerow orchard, in which planting density is approximately 2,000 trees per ha, was developed. In 2006 and 2007, we noted a severe outbreak of fruit rot in FS-17, a new cultivar from Italy, in an experimental hedgerow planting in Córdoba, southern Spain. The incidence of fruit rot in ‘FS-17’ was 80% in January of 2006 and 24% in January of 2007. Cvs. Arbosana, IRTA-i18 (a selected clone from ‘Arbequina’), and Koroneiki had no symptoms in either year of the study. Disease incidence in ‘Arbequina’ was <0.1% only in 2006. Affected fruits were soft with gray-white skin and they eventually mummified. Black-green sporodochia were observed on the surface of diseased fruits. A fungus was isolated from diseased fruits on potato dextrose agar (PDA) and incubated at 22 to 26°C with a 12-h photoperiod. After 8 days of growing on PDA, fungal colonies formed conidial chains having a main axis with up to 10 conidia and secondary and tertiary short branches with two to four conidia. Conidia were obpyriform, ovoid, or ellipsoidal, without a beak or with a short beak, had up to four transverse septa, and measured 11.7 to 24.7 (mean 19.6) μm long and 7.7 to 13.0 (mean 9.6) μm wide at the broadest part of the conidium. The length of the beak of conidia was variable, ranging from 0 to 28.6 (mean 5.5) μm. The fungus was identified as Alternaria alternata (1). Pathogenicity tests were performed by spraying 40 mature fruits of ‘FS-17’ with a spore suspension (1 × 106 spores per ml). The same number of control fruits was treated with water. After 21 days, inoculated fruit developed symptoms that had earlier been observed in the field. A. alternata was reisolated from lesions on all infected fruits. The fungus was not isolated from any of the control fruits. The experiment was performed twice. The new growing system and the high susceptibility of some olive cultivars, such as FS-17, may result in a high incidence of disease caused by a pathogen that is generally characterized as weakly virulent. To our knowledge, this is the first report of A. alternata causing a severe outbreak of fruit rot on olive trees in the field. References: (1) B. M. Pryor and T. J. Michailides. Phytopathology 92:406, 2002.

Water Footprint Accounting for Improving Irrigation Management in Olive Trees

2018 ◽  
pp. 61-72 ◽  
Author(s):  
R. González Perea ◽  
J. García Morillo ◽  
Juan A. Rodríguez Díaz ◽  
Pilar M. Barrios ◽  
Emilio C. Poyato
Keyword(s):  
Water Footprint ◽  
Irrigation Management ◽  
Olive Trees

scholarly journals Spatio-Temporal Response of Vegetation Indices to Rainfall and Temperature in A Semiarid Region

2020 ◽  
Vol 12 (5) ◽  
pp. 1939 ◽  
Author(s):  
Edith Olmos-Trujillo ◽  
Julián González-Trinidad ◽  
Hugo Júnez-Ferreira ◽  
Anuard Pacheco-Guerrero ◽  
Carlos Bautista-Capetillo ◽  
...  
Keyword(s):  
Arid Region ◽  
Climatic Factors ◽  
Time Lag ◽  
Vegetation Indices ◽  
Climatic Variables ◽  
Semiarid Region ◽  
Linear Regression Models ◽  
Spatio Temporal ◽  
Semi Arid Region ◽  
Semi Arid

In this research, vegetation indices (VIs) were analyzed as indicators of the spatio-temporal variation of vegetation in a semi-arid region. For a better understanding of this dynamic, interactions between vegetation and climate should be studied more widely. To this end, the following methodology was proposed: (1) acquire the NDVI, EVI, SAVI, MSAVI, and NDMI by classification of vegetation and land cover categories in a monthly period from 2014 to 2018; (2) perform a geostatistical analysis of rainfall and temperature; and (3) assess the application of ordinary and uncertainty least squares linear regression models to experimental data from the response of vegetation indices to climatic variables through the BiDASys (bivariate data analysis system) program. The proposed methodology was tested in a semi-arid region of Zacatecas, Mexico. It was found that besides the high values in the indices that indicate good health, the climatic variables that have an impact on the study area should be considered given the close relationship with the vegetation. A better correlation of the NDMI and EVI with rainfall and temperature was found, and similarly, the relationship between VIs and climatic factors showed a general time lag effect. This methodology can be considered in management and conservation plans of natural ecosystems, in the context of climate change and sustainable development policies.

scholarly journals Annual Runoff is Highly Linked to Precipitation Extremes in Karst Catchments of Southwest China

2017 ◽  
Vol 18 (10) ◽  
pp. 2745-2759 ◽  
Author(s):  
Zhenwei Li ◽  
Xianli Xu ◽  
Chaohao Xu ◽  
Meixian Liu ◽  
Kelin Wang ◽  
...  
Keyword(s):  
Water Resources ◽  
Southwest China ◽  
Climatic Factors ◽  
Precipitation Amount ◽  
Heavy Precipitation ◽  
Annual Runoff ◽  
Climatic Variables ◽  
Precipitation Extremes ◽  
Karst Area ◽  
Least Squares Regression

Abstract Karst landforms cover 7%–12% of the Earth’s continental area and provide water resources for 25% of the global population. Climate, particularly frequent climate extremes, may greatly affect the annual runoff, especially in climate-sensitive regions such as a karst area of southwest China. Knowledge of the linkage between climate and runoff is urgently needed for smart water resources management. This study therefore selected five catchments that have different carbonized rock coverage (from 11% to 64%) to detect the dominant climatic variables driving changes in annual runoff for the period of 1957–2011 in southwest China. Because climatic variables are highly codependent, a partial least squares regression (PLSR) was used to elucidate the linkages between runoff and 17 climatic variables. Results indicated that the dominant climatic factors driving annual runoff are annual total precipitation, rainy days, heavy precipitation amount, heavy precipitation days, rainstorm amount, and rainstorm days. These six factors are generally used to represent extreme climatic events, and hence it may demonstrate that annual runoff is highly linked to precipitation extremes in this region. The PLSR approach presented in this study is beneficial and novel, as it enables the elimination of codependency among the variables and facilitates a more unbiased view of the contribution of the changes in climatic variables to the changes in runoff. As a practical and simple tool, the PLSR approach is thus recommended for application to a variety of other catchments.

scholarly journals Vegetation Degradation and Its Driving Factors in the Farming–Pastoral Ecotone over the Countries along Belt and Road Initiative

2019 ◽  
Vol 11 (6) ◽  
pp. 1590 ◽  
Author(s):  
Qionghuan Liu ◽  
Xiuhong Wang ◽  
Yili Zhang ◽  
Huamin Zhang ◽  
Lanhui Li
Keyword(s):  
Vegetation Change ◽  
Vegetation Index ◽  
Climatic Factors ◽  
Growth Strategy ◽  
Livestock Grazing ◽  
Climatic Variables ◽  
Belt And Road Initiative ◽  
Vegetation Degradation ◽  
Belt And Road ◽  
Anthropogenic Contributions

To adhere to the green growth strategy, it is urgently needed to identify the vegetation degradation zone in the farming–pastoral ecotone (FPE) over the countries along the “Belt and Road Initiative (BRI)”. In this study, we monitored vegetation degradation and analyzed climatic factors and anthropogenic contributions on vegetation change in the FPE during 2000–2016 using the growing season annual accumulative normalized difference vegetation index (NDVIaccu) and climatic variables. The Theil-Sen’s trend results revealed that 74.11% of NDVIaccu in FPEs showed a significant increasing trend for the period 2000–2016, only 1.64% of NDVIaccu were significantly decreasing. However, we detected that 21.29% degradation of NDVIaccu had occurred based on enhanced Theil-Sen and Mann-Kendall (ETheil-Sen-MK) method. Spatial statistics for significant correlations between climatic variables and NDVIaccu showed that precipitation was positively correlated with NDVIaccu; yet, the relationship between NDVIaccu and temperature was more complex, which was closely related to the intensity of increasing in temperature. Importantly, this study found that anthropogenic contributions dominated the trends in NDVIaccu over the FPE. The findings suggested that agricultural activities play a mainly positive role in overall vegetation vigor. However, continually increasing disturbance by livestock grazing risks further vegetation degradation.

scholarly journals Molecular Variability Within and Among Verticillium dahliae Vegetative Compatibility Groups Determined by Fluorescent Amplified Fragment Length Polymorphism and Polymerase Chain Reaction Markers

2006 ◽  
Vol 96 (5) ◽  
pp. 485-495 ◽  
Author(s):  
Melania Collado-Romero ◽  
Jesús Mercado-Blanco ◽  
Concepción Olivares-García ◽  
Antonio Valverde-Corredor ◽  
Rafael M. Jiménez-Díaz
Keyword(s):  
Polymerase Chain Reaction ◽  
Length Polymorphism ◽  
Verticillium Dahliae ◽  
Fragment Length ◽  
Fragment Length Polymorphism ◽  
Chain Reaction ◽  
Vegetative Compatibility Groups ◽  
Molecular Variability ◽  
Polymerase Chain ◽  
Olive Trees

A degree of genetic diversity may exist among Verticillium dahliae isolates within vegetative compatibility groups (VCGs) that bears phytopathological significance and is worth investigating using molecular tools of a higher resolution than VCG characterization. The molecular variability within and among V. dahliae VCGs was studied using 53 artichoke isolates from eastern-central Spain, 96 isolates from cotton, 7 from cotton soil, and 45 from olive trees in countries of the Mediterranean Basin. Isolates were selected to represent the widest available diversity in cotton- and olive-defoliating (D) and -nondefoliating (ND) pathotypes, as well as for VCG. The VCG of 96 cotton and olive isolates was determined in this present study. Molecular variability among V. dahliae isolates was assessed by fluorescent amplified fragment length polymorphism (AFLP) analysis and by polymerase chain reaction (PCR) assays for DNA fragments associated with the D (462 bp) and ND (824 bp) pathotypes, as well as a 334-bp amplicon associated with D pathotype isolates but also present in some VCG2B isolates. Isolates from cotton were in VCG1A, VCG1B, VCG2A, VCG2B, and VCG4B and those from olive trees were in VCG1A, VCG2A, and VCG4B. Artichoke isolates included representatives of VCG1A, VCG2A, VCG2B (including a newly identified VCG2Ba), and VCG4B. AFLP data were used to generate matrixes of genetic distance among isolates for cluster analysis using the neighbor-joining method and for analysis of molecular variance. Results demonstrated that V. dahliae isolates within a VCG subgroup are molecularly similar, to the extent that clustering of isolates correlated with VCG subgroups regardless of the host source and geographic origin. VCGs differed in molecular variability, with the variability being highest in VCG2B and VCG2A. For some AFLP/VCG subgroup clusterings, V. dahliae isolates from artichoke grouped in subclusters clearly distinct from those comprising isolates from cotton and olive trees. In addition, VCG2B isolates from artichoke formed two distinct clusters that correlated with PCR markers of 334 bp (VCG2B334) or 824 bp (VCG2B824). Artichoke isolates in the VCG2B334/2β334 cluster were molecularly similar to isolates of VCG1A. The molecular difference found among artichoke isolates in VCG2B correlates with virulence of isolates to artichoke and cotton cultivars demonstrated in a previous study.

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