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![Disease severity [RAUDPC (%; dark grey columns) and Final disease severity (%; light grey columns)] of branch dieback of almond trees under natural conditions in an experimental field (Córdoba, Andalusia region, southern Spain) subjected to four irrigation treatments from April 2013 to October 2019 (T0: Control; T1: Moderate Regulated Deficit Irrigation; T2: Moderate Sustained Deficit Irrigation; T3: Severe Regulated Deficit Irrigation). The disease severity assessments were conducted from June 2018 (next spring after first symptoms of branch dieback occur) to September 2019 (end of the experiment). For each disease parameter, columns represent the means of sixteen trees and vertical bars are the standard errors of the means. Columns with different capital or lowercase letters differ significantly for RAUDPC, or Final disease severity, respectively, according to Fisher's LSD test at P = 0.05.](publication/344322038/figure/fig1/AS:974190911967233@1609276621227/Disease-severity-RAUDPC-dark-grey-columns-and-Final-disease-severity-light-grey.png)
Disease severity [RAUDPC (%; dark grey columns) and Final disease severity (%; light grey columns)] of branch dieback of almond trees under natural conditions in an experimental field (Córdoba, Andalusia region, southern Spain) subjected to four irrigation treatments from April 2013 to October 2019 (T0: Control; T1: Moderate Regulated Deficit Irrigation; T2: Moderate Sustained Deficit Irrigation; T3: Severe Regulated Deficit Irrigation). The disease severity assessments were conducted from June 2018 (next spring after first symptoms of branch dieback occur) to September 2019 (end of the experiment). For each disease parameter, columns represent the means of sixteen trees and vertical bars are the standard errors of the means. Columns with different capital or lowercase letters differ significantly for RAUDPC, or Final disease severity, respectively, according to Fisher's LSD test at P = 0.05.
Source publication
Branch dieback and tree decline have been described as a common complex disease worldwide in woody crops, with Botryosphaeriaceae and Diaporthaceae being considered the most frequent fungi associated with the disease symptoms. Their behaviour is still uncertain, since they are considered endophytes becoming pathogenic in weakened hosts when stress...
Contexts in source publication
Context 1
... 5.1%; Final disease severity = 71.3 ± 9.1%) and T1 (Moderate Regulated Deficit Irrigation; RAUDPC = 28.5 ± 4.5%; Final disease severity = 59.1 ± 6.5%) (Figures 1 and 2). Almond trees used as control (T0) showed the lowest values of RAUDPC (22.2 ± 1.5%), as well as the lowest values of final disease severity (42.2 ± 4.1%) (Figures 1 and 3). ...
Context 2
... 9.1%) and T1 (Moderate Regulated Deficit Irrigation; RAUDPC = 28.5 ± 4.5%; Final disease severity = 59.1 ± 6.5%) (Figures 1 and 2). Almond trees used as control (T0) showed the lowest values of RAUDPC (22.2 ± 1.5%), as well as the lowest values of final disease severity (42.2 ± 4.1%) (Figures 1 and 3). Control trees did not show internal wood discoloration. ...
Context 3
... 5.1%; Final disease severity = 71.3 ± 9.1%) and T1 (Moderate Regulated Deficit Irrigation; RAUDPC = 28.5 ± 4.5%; Final disease severity = 59.1 ± 6.5%) (Figures 1 and 2). Almond trees used as control (T0) showed the lowest values of RAUDPC (22.2 ± 1.5%), as well as the lowest values of final disease severity (42.2 ± 4.1%) (Figures 1 and 3). ...
Context 4
... 9.1%) and T1 (Moderate Regulated Deficit Irrigation; RAUDPC = 28.5 ± 4.5%; Final disease severity = 59.1 ± 6.5%) (Figures 1 and 2). Almond trees used as control (T0) showed the lowest values of RAUDPC (22.2 ± 1.5%), as well as the lowest values of final disease severity (42.2 ± 4.1%) (Figures 1 and 3). Control trees did not show internal wood discoloration. ...
Context 5
... trees did not show internal wood discoloration. Figure 1. Disease severity [RAUDPC (%; dark grey columns) and Final disease severity (%; light grey columns)] of branch dieback of almond trees under natural conditions in an experimental field (Córdoba, Andalusia region, southern Spain) subjected to four irrigation treatments from April 2013 to October 2019 (T0: Control; T1: Moderate Regulated Deficit Irrigation; T2: Moderate Sustained Deficit Irrigation; T3: Severe Regulated Deficit Irrigation). ...
Citations
... Besides, latent infections of S. banihashemiana can occur in asymptomatic trees (Negahban et al. 2024). Certain environmental conditions, such as abiotic stresses, including temperature stress and drought, can trigger endogenous activation of latent infections (Agustí-Brisach et al. 2020). These stresses may affect the plant's immune system and its microbiota (Teixeira et al. 2019;Luo et al. 2019). ...
Stilbocrea banihashemiana is a recently described species of ascomycete fungi (Bionectriaceae) that causes canker and dieback diseases on fig and barberry, and dieback on loquat trees. Previous studies suggested this pathogen might affect other trees including economically important fruit crops, such as almonds, apples, and olives. This study assessed the susceptibility of 40 tree species belonging to 20 plant families, including fruit-bearing, ornamental, and edible landscape plants, to S. banihashemiana. The assessment was conducted by wound-inoculating detached shoots and one-year-old saplings with the pathogen. Based on five parameters of induced lesions, we clustered the inoculated tree species using the principal component analysis approach. The results of the approach revealed four distinct groups of tree species based on their susceptibility traits. Almond, apricot, eucalyptus, poplar, and red mulberry clustered in one group as susceptible hosts. The majority of the species examined, which included both tropical and temperate trees, were categorized as moderately susceptible. Platanus and sweet orange were identified as non-host-resistant species, while Arizona cypress, garden privet, and olive were classified as low susceptible. Moreover, our findings suggest a correlation between temperature and the aggressiveness of S. banihashemiana. This study revealed that the emerging pathogen, S. banihashemiana, could have a broader host range than currently recognized. The accidental introduction of this pathogen through the global trade of live host plants may pose a significant threat to economically important trees in temperate and subtropical regions.
... For instance, early varieties can be the first to flower and the last to ripen [49]. Branch dieback is one of the diseases that affect almond orchard viability and is caused by Botryosphaeria dothidea, Neofusicoccum mediterraneum, Diaporthe Neotheicola, Diaporthe Rhusicola, and Cytospora cedri [59]. Phomopsis amygdali, Fusicoccum amygdali Delacr., and Diaporthe amygdali Delacr. ...
... Phomopsis amygdali, Fusicoccum amygdali Delacr., and Diaporthe amygdali Delacr. are a few agents that cause twig canker and shoot blight in almonds, which causes necrosis and the death of plant organs [59,60]. According to León et al. [60], in coastal areas with higher humidity and milder temperatures, the proliferation of these fungi is recurrent. ...
... mediterraneum, Neof. parvum, and Dothiorella sarmentorum were identified from canopy cankers [59,63,64]. In addition, Diaporthe australafricana and Diaporthe novem were observed in almond orchards [60]. ...
Climate change is one of the most emergent environmental challenges, with rising global temperatures, changes in precipitation regimes, and an increased frequency and intensity of extreme weather events. Climate change impacts on the agrarian sector are being experienced across the world and are expected to be aggravated in the upcoming decades. Almond fruits are highly sought after due to their economic and nutritional interest, which contribute to their spread throughout the world. In 2021, the world almond production was approximately 3.9 × 10 6 t with upward of 4.9 × 10 3 t year −1. Despite being relatively drought-and heat-resistant, this species is also vulnerable to climate change, particularly its production, which is highly dependent on soil water content and air temperature. To address the challenges of climate change, farmers and other stakeholders in the almond industry are increasingly adopting a range of adaptation measures, such as implementing irrigation systems and planting more drought-tolerant almond varieties. This manuscript describes the impacts of climate change on almond cultivation, reviewing the most recent studies on the subject. Furthermore, a comprehensive analysis of possible adaptation strategies against the potentially negative impacts is carried out, which might be of relevance to almond producers and other stakeholders operating in this value chain.
... Fungi of the Botryosphaeriaceae family are one of the most prevalent pathogens in almond orchards [13,16,21]. Many Botryosphaeriaceae species have been associated with almond cankers worldwide (Botryosphaeria dothidea, Diplodia corticola, D. gallae, D. mutila, D. olivarum, D. seriata, Dothiorella iberica, Do. prunicola, Do. sarmentorum, Do. viticola, Lasiodiplodia theobromae, Macrophomina phaseolina, Neofusicoccum arbuti, N. australe, N. luteum, N. mediterraneum, N. nonquaesitum, N. parvum, N. vitifusiforme and Neoscytalidium dimidiatum) [5,13,15,16,18,[21][22][23]25] with Neofusicoccum being the prevailing genus [24]. Regarding other nut crops, N. parvum is also the dominant species in walnut orchards in Australia, California, China, Chile, Italy, Iran and Spain [18,[26][27][28][29][30][31][32], and N. mediterraneum prevails in Spanish and Californian pistachio orchards [33,34]. ...
... Among the Botryosphaeriaceae family, Neofusicoccum parvum and Botryosphaeria dothidea have been reported as the most aggressive and most prevailing species in Spanish almond crop, respectively [21,23]. However, since the accurate identification of the causal agents is not easy and canker diseases can be caused by more than one pathogen, the objectives of this work were (i) to develop sensitive and reliable qPCR methods based on TaqMan probes for the simultaneous detection of (a) N. parvum and the Neofusicoccum genus, (b) N. parvum and the Botryosphaeriaceae family and (c) B. dothidea and the Botryosphaeriaceae family, in almond; (ii) to validate the designed protocols in artificially and naturally infected almonds by using two methods of sample preparation: extraction of DNA from infected tissues and direct preparation of plant crude extracts; and (iii) to apply the designed duplex qPCRs for the detection of the latent infection of Botryosphaeriaceae species in almond. ...
Woody canker diseases caused by fungi of the Botryosphaeriaceae family are producing increasing losses in many economically important woody crops, including almond. To develop a molecular tool for the detection and quantification of the most aggressive and threatening species is of main importance. This will help to prevent the introduction of these pathogens in new orchards and to conveniently apply the appropriate control measures. Three reliable, sensitive and specific duplex qPCR assays using TaqMan probes have been designed for the detection and quantification of (a) Neofusicoccum parvum and the Neofusicoccum genus, (b) N. parvum and the Botryosphaeriaceae family and (c) Botryosphaeria dothidea and the Botryosphaeriaceae family. The multiplex qPCR protocols have been validated on artificially and naturally infected plants. Direct systems to process plant materials, without DNA purification, allowed high-throughput detection of Botryosphaeriaceae targets even in asymptomatic tissues. These results validate the qPCR using the direct sample preparation method as a valuable tool for Botryosphaeria dieback diagnosis allowing a large-scale analysis and the preventive detection of latent infection.
... Studies conducted in vitro as well as in vivo in California regarding the relationship between drought stress and the Botryosphaeria panicle and shoot blight of pistachio, showed that the mycelial growth of B. dothidea increased as Ψs decreased from 0 to 2.0 -MPa and declined as Ψs decreased below 2.0 -Mpa in laboratory conditions, and the severity of the disease increased under water stress conditions (Ma et al., 2001). Similarly, diseases caused by Botryosphaeriaceae have been reported to increase under severe water stress in other hosts, such as apple, sweetgum, European white birch, peach, dogwood, and almond (Hutton, 1958;Neely, 1968;Crist & Schoeneweiss, 1975;Pusey, 1989;Mullen et al., 1991;Agustí-Brisach et al., 2020). Our laboratory results are not in accordance with what observations of Ma et al. (2001) for B. dothidea, but we do not exclude at all the possibility that N. dimidiatum infections in the fields could be seriously aggravated by drought stress. ...
... As observed in a previous study (Gusella et al., 2021), different stress factors severely influence infections by N. dimidiatum. Moreover, studies conducted by Agustí-Brisach et al. (2020) on almond branch dieback and decline revealed that symptoms were observed mainly in the experimental plots of trees irrigated with less amount of water, with consistency of fungal isolation (mainly Botryosphaeriaceae) increasing with the disease severity. ...
The San Joaquin Valley (California, USA) represents an important fig (Ficus carica) production area in the United States. Fig limb dieback represents a serious and emerging disease of fig caused by Neoscytalidium dimidiatum. In the present study we evaluated the effect of tissue age on canker development, the recovery of the fungus from fruit mummies collected in the field, the ability of N. dimidiatum to colonize, under laboratory condition, fig fruits, and the in vitro effects of different water potentials (Ψs) on mycelial growth rate.Results of our study showed that the older branches (> 3-year-old) resulted in longer canker compared to the younger ages. N. dimidiatum was not recovered from the mummies, instead they were colonized by many other fungal saprophytes. Laboratory experiments showed the ability of this species to colonize dried fig fruits from 20 °C to 35 °C. In vitro water potentials experiment showed that the mycelial growth was reduced with the decrease of water potential (from 1–3 -MPa), depending on salt type.
... Besides climatic factors and anthropogenic pressure, the preservation of the species strongly depends on biotic factors which necessarily include fungi associated with the plant. The mycobiota of apricot as well as other species of Prunus is studied mostly regarding fungal pathogenicity on shoots with manifestations of diseases [12][13][14][15][16][17][18][19][20]. Healthy or asymptomatic shoots and branches have been also studied for endophytic fungi in some Prunus species: Prunus africana (Hook. ...
Prunus mandshurica is a rare species of the Russian Far East; it is cultivated for fruits and as an ornamental tree. The objective was to determine the fungi associated with young shoots of the Manchurian apricot, which is an important biotic factor for plant viability and productivity. Fungi were isolated by incubation of shoot fragments (unsterilized or surface-sterilized) on a growth medium and identified according to their cultural and morphological characteristics. Diaporthe eres and Nothophoma quercina isolates were identified by multilocus phylogenetic analysis (apn2, cal, tef1-α, tub2 for D. eres, and ITS, rpb2, tub2 for N. quercina). In total, 12 species (Alternaria alternata, A. tenuissima, Aureobasidium pullulans, Cladosporium cladosporioides, C. herbarum, D. eres, Epicoccum nigrum, Fusarium graminearum, F. oxysporum, N. quercina, Sarocladium strictum, and Tripospermum myrti) and one genus (Gliocladium sp.) were found. Alternaria alternata, N. quercina, and D. eres were the most frequent species of the shoots. Alternaria tenuissima and F. oxysporum were also frequent in some collections, while all other species were rare or occasional in occurrence. Molecular analysis of D. eres and N. quercina revealed redundancy of some species within the D. eres species complex and the genus Nothophoma. This is the first report on the fungal inhabitants of asymptomatic shoots of P. mandshurica. Nothophoma quercina was identified in Russia for the first time.
... The survey of fig and loquat orchards in southern Iran during 2019-2021 revealed S. banihashemiana was commonly associated with symptoms of stem cankers, twig dieback, and internal wood discoloration leading to tree decline. In previous studies, a high incidence of tree decline incited by fungi infecting stems and twigs was imputed to several factors, including a local abundance of fungal inoculum and environmental conditions predisposing the tree to the infection, such as frost, drought, water, and heat stresses [41,[52][53][54]. Moreover, recently it has been highlighted a correlation between the presence of fungi associated with GTDs and the origin of propagation material, corroborating the hypothesis that fungi causing stem cankers and twig dieback in commercial orchards originate from the nursery and an endophytic lifestyle favors their spread through asymptomatic plants [41,[55][56][57][58][59]. ...
Stem cankers and twig dieback were the most serious disease of fig (Ficus carica) and loquat (Eriobotrya japonica) noticed in a survey of fruit tree orchards in the Fars Province, Iran. Isolates of Bionectriaceae were consistently recovered from symptomatic fig and loquat trees. Phylogenetic analyses of multiple nuclear loci, internal transcribed spacer regions (ITS) of rDNA, RNA polymerase II subunit 2 (rpb2), and translation elongation factor 1-α (tef1), combined with morphological observations, revealed that isolates could be referred to a still unknown taxon, which was formally described as Stilbocrea banihashemiana sp. nov. Phylogenetically, isolates from fig and loquat trees clustered in a well-supported monophyletic group within the Stilbocrea clade of Bionectriaceae, closely related to S. walteri. Stilbocrea banihashemiana sp. nov. was characterized by the lack of stilbella-like asexual structure in both natural substrates and pure cultures and produced two morphologically distinct types of conidia, globose and cylindrical, formed on short and long simple phialides. In pathogenicity tests, S. banihashemiana sp. nov. induced stem cankers in both fig and loquat, wood discoloration in fig and twig dieback in loquat. Pathogenicity tests also showed that the potential host range of this novel pathogen includes other economically relevant horticultural trees.
... Therefore, a rational approach to sustainable use of water in different crops should include the effects on the most relevant biotic factors (pests and diseases) that affect the crops. The effects of deficit irrigation on arthropod populations and diseases are not usually considered in scientific production, but recent changes in crop management in Spain to more productive methods have promoted such studies in super-intensive olive [34,35] and irrigated almond [23,36] orchards. ...
Irrigated almond orchards in Spain are increasing in acreage, and it is pertinent to study the effect of deficit irrigation on the presence of pests, plant damage, and other arthropod communities. In an orchard examined from 2017 to 2020, arthropods and diseases were studied by visual sampling under two irrigation treatments (T1, control and T2, regulated deficit irrigation (RDI)). Univariate analysis showed no influence of irrigation on the aphid Hyalopterus amygdali (Blanchard) (Hemiptera: Aphididae) population and damage, but Tetranychus urticae Koch (Trombidiformes: Tetranychidae) damage on leaves was significantly less (50–60% reduction in damaged leaf area) in the T2 RDI treatment compared to the full irrigation T1 control in 2019 and 2020. Typhlocybinae (principal species Asymmetrasca decedens (Paoli) (Hemiptera: Cicadellidae)) population was also significantly lower under T2 RDI treatment. Chrysopidae and Phytoseiidae, important groups in the biological control of pests, were not affected by irrigation treatment. The most important diseases observed in the orchard were not, in general, affected by irrigation treatment. The multivariate principal response curves show significant differences between irrigation strategies in 2019 and 2020. In conclusion, irrigation schemes with restricted water use (such as T2 RDI) can help reduce the foliar damage of important pests and the abundance of other secondary pests in almond orchards.
In 2016, an almond (Prunus dulcis) decline syndrome (ADS) emerged in intensive almond plantations in the Andalusia region (southern Spain), showing branch dieback, gummosis, and general tree decline. The aim of this work was to elucidate the etiology of this disease complex. For this purpose, surveys were conducted across the Andalusia region, and a wide collection of fungi was recovered from wood samples showing gum and internal discoloration. Representative isolates were selected and identified by sequencing the ITS, TEF1, TUB, ACT, LSU and/or RPB2 genes. The following fungal species were identified to be associated with the disease: Botryosphaeria dothidea, Diplodia corticola, Di. seriata, Dothiorella iberica, Lasiodiplodia viticola, Macrophomina phaseolina, Neofusicoccum mediterraneum, N. parvum, N. vitifusiforme, Diaporthe neotheicola, Dia. rhusicola, Dia. ambigua, Eutypa lata, E. tetragona, Eutypella citricola, Eu. microtheca, Fusarium oxysporum s.l., Pleurostoma richardsiae, Phaeoacremonium iranianum, Pm. krajdenii, Pm. parasiticum and Cytospora sp. All isolates were tested for pathogenicity by inoculating detached or attached almond shoots. Di. corticola and N. parvum were the most aggressive species, showing the largest lesions and most gummosis in attached shoots. The results suggest that the species belonging to Botryosphaeriaceae play a key role in disease development, while the remaining identified species may act as secondary pathogens or endophytes. However, further research to determine the interaction between all these fungal species and other biotic and abiotic factors in the ADS progress is needed.
Fig canker is a serious concern in the major fig‐growing region of Iran, Fars Province. The disease reduces yield and the lifespan of fig trees, particularly the dominant commercial dried fig cultivar, 'Sabz'. Four years of consecutive surveys (2019–2022) led to the identification of four distinct canker types (A‐D), in the infected fig orchards in southern Iran. Morphological identification and multiple gene genealogy analyses indicated that 218 (>%66 of the total) isolates from infected fig cultivars belonged to Diaporthe cinerascens, all of which were recovered from type A canker, i.e., trunk cankers with zonation. Based on scales developed by the principal component analysis (PCA) approach of pathogenicity characteristics, D. cinerascens isolates were clustered into three groups, including low, moderate, and highly aggressive. The susceptibility of the 10 drought and/or salinity‐tolerant fig cultivars to a highly aggressive D. cinerascens isolate was evaluated based on five pathogenicity characteristics. These cultivars were clustered into non‐susceptible ('Matti' cultivar), semi‐susceptible (the majority of the cultivars), and susceptible cultivars ('Dehdez' and 'Gilasi'). The present study is the first attempt to assess fig cultivars' response to the most significant and common fig canker‐causing pathogen, D. cinerascens, via phenotyping techniques.
