From March 2020 to November 2022, 12 commercial almond (Prunus dulcis) orchards showing symptoms of chlorosis, wilting, defoliation, cankers, crown rot and profuse trunk gummosis were surveyed in southern Spain and Portugal. Diagnostic tests were performed by isolating oomycetes from affected tissues and by DNA extraction from root and wood tissues and PCR amplification of the rDNA internal transcribed spacer (ITS) genomic area using the specific primer pair Phni-F/Phni-R. A total of 62 isolates were collected: 18 Phytophthora-like isolated from plants and 44 Pythium sensu lato-like from waterlogged soil. Seven representative isolates were selected and identified by multilocus sequencing of the ITS and cox2 genomic regions and phylogenetic analysis. The following oomycetes were identified: Phytophthora niederhauseri, Phytopythium litorale, Globisporangium heterothallicum, G. macrosporum, G. paroecandrum and G. violae, with Ph. niederhauseri being the most frequent. The effect of temperature on the mycelial growth of seven isolates was evaluated in carrot agar and corn meal agar, with Ph. niederhauseri and Pp. litorale showing the highest optimal growth temperature (around 28 degrees C-29 degrees C) regardless of the culture media used. Pathogenicity tests of seven isolates were conducted on almond plants of cv. Guara grafted on Garnem rootstock. Ph. niederhauseri isolates were the most aggressive, causing crown rot, gummosis and plant death starting 3 weeks after inoculation. Pp. litorale showed intermediate aggressiveness, while Globisporangium species developed small cankers and minimum lesions, not causing plant death. Based on pathogenicity tests, Ph. niederhauseri is considered the true pathogen of the disease, while the Pythium sensu lato-like isolates must be considered secondary pathogens in waterlogged conditions.

Controlling Verticillium wilt of olive (VWO), caused by the fungus Verticillium dahliae, is a challenge in all olive-growing regions worldwide. Although a wide variety of strategies against this disease have been evaluated, they are not useful for achieving optimal control. Biological control has been postulated as one of the most promising alternatives to prevent VWO. Thus, the goal of this study was to evaluate the effects of 19 natural products and microbial strains, including amino acids, microorganisms, organic amendments, biofertilizers based on copper and potassium, and essential thyme oils, under field conditions. The compounds were selected from 49 treatments that were previously evaluated against V. dahliae under laboratory or field conditions to confirm or validate their effectiveness against VWO. To this end, two experimental fields of the olive cv. Picual were established in orchards with moderate V. dahliae inoculum densities in the soil as representative of the main olive growing areas across southern Spain. The treatments were applied by spraying or irrigation in spring and autumn, and the disease severity was monitored over three experimental years. Our results confirmed the effectiveness of Fusarium oxysporum FO12, the organic amendment olive waste compost CAL03 and grape marc compost CGR03, and the CAL03 + FO12 mixture as the most effective treatments against VWO in the field. This work provides useful information about the use of environmentally friendly products against VWO.

Cadophora luteo-olivacea, Phaeoacremonium minimum, and Pseudophaeomoniella oleicola have been associated with branch dieback, shoot blight, and vascular wilt in super-high-density olive plantations in Spain. In this study, the effects of the interaction between these three fungal species on the disease progression were evaluated through multi-infections inoculated by spore suspensions or mycelial plugs in olive plants of cultivar Arbequina. The susceptibility of six olive cultivars was also evaluated against these three pathogens by single inoculations with conidial suspensions. The detection and inoculum quantification of each fungal species from coinfected plant tissues or from inoculated plants of different cultivars was conducted by qPCR, using species-specific primers. In addition, a species-specific primer to identify Ps. oleicola was developed in this study. In the multi-infections experiment with conidial suspensions, lesions on olive infected simultaneously with all three species were larger than those on plants coinfected by two species, which were, in turn, larger than those inoculated by a single species. However, when inoculations were conducted with mycelial plugs, C. luteo-olivacea caused larger lesions than those in coinfected plants. The quantification of these fungi through qPCR suggests that their interaction during coinfections significantly alters their relative abundance, potentially impacting their aggressiveness. Regarding the cultivar resistance experiment, the most susceptible cultivar to the disease was 'Koroneiki', followed by 'Arbequina' and 'Picual'. In all the samples, the detection of C. luteo-olivacea was an order of magnitude lower than that of the other fungal species. Nevertheless, the relative quantification of fungi by qPCR, despite being useful to detect the presence of the pathogen, does not correlate with the lesions observed.

Bioprotection through the use of plant extracts is an environmentally friendly strategy in crop protection. Effective control of Verticillium wilt of olive (Olea europaea; VWO), caused by Verticillium dahliae, has proven challenging because of the ineffectiveness of chemicals, which makes it necessary to search for new control tools. Thus, the aim of this study was to evaluate the effect of pomegranate (Punica granatum) and carob (Ceratonia siliqua) extracts on VWO. Extracts derived from pomegranate peels and carob pods and leaves were obtained using ethanol, methanol, or ethyl acetate as a solvent. A targeted analysis of their metabolite composition was performed using QTRAP ultrahigh-performance liquid chromatography with mass spectrometry. Remarkably, gallic acid was detected in all extracts at a high concentration. The effect of the extracts on the mycelial growth and on the germination of conidia and microsclerotia of V. dahliae was evaluated by in vitro sensitivity tests at various doses: 0 (control), 3, 30, 300, and 3,000 mg of extract/liter. Extracts obtained with ethanol or methanol significantly reduced the viability of V. dahliae structures when applied at the highest dose, while those obtained with ethyl acetate were ineffective across all doses. The most effective extracts, as determined in vitro, were then evaluated against the disease in olive plants. Potted plants of the cultivar Picual were treated by spraying (foliar application) or irrigation (root application) of extracts at 3,000 mg/liter, followed by inoculation with V. dahliae. The results indicated that foliar applications were ineffective, while root treatments with pomegranate peel or carob leaf extracts were more effective in reducing disease severity, regardless of the solvent, compared with that of the untreated control.

The nonpathogenic strain Fusarium oxysporum FO12 has been characterized as an effective biological control agent against Verticillium dahliae in olive. Nevertheless, the endophytic role of FO12 in herbaceous hosts is still uncertain. Thus, the aim of this study was to demonstrate the nonpathogenic character of FO12 in eight V. dahliae-susceptible herbaceous hosts and to evaluate its ability to promote plant growth. To this end, plants of each host were grown in pots filled with sterile peat moss and inoculated by irrigation with a conidial suspension of FO12 (106 conidia ml−1) two times—at sowing and at the emergence of the first true leaves. Many plants irrigated with sterile distilled water were included as controls. Sampling was conducted at 7, 14, 21, and 28 days after the second inoculation. The fresh weight and length of the aerial parts, roots, and whole plants were determined at each sampling time. Fungal colonization was assessed via quantitative and qualitative methods, including microbiological isolation from roots and stems and confocal laser scanning microscopy (CLSM) imaging at each sampling time. FO12 exhibited the ability to endophytically colonize the roots and stems of the inoculated plants. However, the effect on growth and the degree of colonization varied depending on the host. FO12 did not exert any evident pathogenic effects or negative effects on plant growth or development. The growth of the eggplant, lettuce, and tomato plants in the FO12 treatment group was similar to that in the control group, whereas the relative area under the growth progress curve was significantly greater than that in the control group for plant length in cotton and cucumber; for root fresh weight in pepper, sunflower, and wheat; and for plant fresh weight in sunflower and wheat. These results highlight the need to continue researching the interaction between FO12 and V. dahliae in a wider range of plant species of agronomic interest.

Severe Fusarium wilt and crown root symptoms were observed in almond orchards in Portugal. The present study elucidates the etiology of the disease through molecular, phenotypic, and pathogenic characterization. Three Fusarium isolates from Portugal were tested and 12 Fusarium isolates from almond from Spain were included for comparative purposes. Their identity was inferred by phylogenetic analysis combining tef1 and rpb2 sequences. The Portuguese isolates were identified as Fusarium oxysporum sensu stricto (s.s.), and the Spanish isolates as Fusarium nirenbergiae, F. oxysporum (s.s.), Fusarium proliferatum, Fusarium redolens (s.s.), Fusarium sambucinum (s.s.), and Fusarium sp. Fungal colonies and conidia were characterized on potato dextrose agar (PDA) and on Synthetischer Nährstoffarmer agar, respectively. The colonies had a variable morphology and their color ranged from white to pale violet. Typical Fusarium micro- and macroconidia were characterized. Temperature effect on mycelial growth was evaluated on PDA from 5 to 35 °C, with optimal growth temperature ranging between 16.8 and 26.4 °C. The pathogenicity of F. oxysporum was demonstrated by inoculating almond plants (‘Lauranne’) grafted on GF-677 or Rootpac 20 rootstocks. A significant reduction in plant growth, wilting, and xylem discoloration was observed, with Rootpac 20 being more susceptible than GF-677. Infections were also reproduced using naturally infested soils. Almond plants (‘Lauranne’) were inoculated with isolates of all Fusarium species, with F. redolens from Spain and F. oxysporum from Portugal being the most aggressive.

Verticillium wilt of pistachio (Pistacia vera), caused by Verticillium dahliae, is one of the most important diseases in this crop. The most effective and economical control measure is the use of resistant rootstocks. The main objective of this work was to evaluate the resistance of five rootstocks commonly used in pistachio against the disease under field conditions. Pistachio plants (cv. Kerman) grafted on the rootstocks Pistacia atlantica, Pistacia integerrima, Pistacia terebinthus and cv. Platinum and UCBI hybrids, were planted in a field with high inoculum density of V. dahliae in the soil. Plants grafted on P. terebinthus, followed by P. integerrima, showed significantly higher disease severity values than the rest of the rootstocks almost 53 months after planting; also, plants grafted on P. atlantica were more resistant than those grafted on P. integerrima. These results highlighted the intraspecific variability in resistance to the disease. In addition, the disease was monitored in pistachios grafted onto P. terebinthus or UCBI in an established commercial field with three different zones of V. dahliae inoculum density in the soil (none, low or high). In the high‐density zone, the percentage of diseased plants was significantly lower for plants grafted on UCBI than for those grafted on P. terebinthus. The results indicate the importance of rootstock species and specific genotype or seed population used, concentration of V. dahliae inoculum in the soil, and previous history of crops on the plot, on the development of the disease under natural conditions.

In the Mediterranean Basin, the pistachio crop is considered an emerging nut crop due to the dependence of the European nut markets on international imports. Consequently, the extension and intensification of pistachio production to nontraditional growing areas has promoted both classic and emerging diseases of this nut tree, which are limiting factors in crop production. Due to the limited interest in pistachio crops, the aetiology and epidemiology of the main pistachio diseases are poorly studied. Thus, this review summarizes the state of pistachio disease research, with particular attention given to the Mediterranean area. The information reported here is based not only on the literature, but also the advancement of our research on pistachio diseases conducted in both Italy and Spain. We describe the main fungal diseases of the tree canopy in Mediterranean countries, such as Botryosphaeria panicle and shoot blight, Septoria leaf spot, and stem, branch and trunk canker diseases, followed by the main soilborne diseases. In addition, we review minor and/or sporadic fungal diseases originating in not only the Mediterranean, but also other pistachio-producing countries. Another section is dedicated to other diseases caused by bacteria, phytoplasmas, viruses and nematodes. Finally, we summarize the main control strategies adopted in Mediterranean Basin countries against pistachio diseases.

Verticillium wilt of olive (VWO) caused by Verticillium dahliae is considered a major olive (Olea europaea) disease in Mediterranean-type climate regions. The lack of effective chemical products against VWO makes it necessary to search for alternatives such as biological control. The main goal of this study was to evaluate the effect of six Streptomyces spp. strains as biological control agents (BCAs) against VWO. All of them were molecularly characterized by sequencing 16S or 23S rRNA genes and via phylogenetic analysis. Their effect was evaluated in vitro on the mycelial growth of V. dahliae (isolates V004 and V323) and on microsclerotia (MS) viability using naturally infested soils. Bioassays in olive plants inoculated with V. dahliae were also conducted to evaluate their effect against disease progress. In all the experiments, the reference BCAs Fusarium oxysporum FO12 and Aureobasidium pullulans AP08 were included for comparative purposes. The six strains were identified as Streptomyces spp., and they were considered as potential new species. All the BCAs, including Streptomyces strains, showed a significant effect on mycelial growth inhibition for both V. dahliae isolates compared to the positive control, with FO12 being the most effective, followed by AP08, while the Streptomyces spp. strains showed an intermediate effect. All the BCAs tested also showed a significant effect on the inhibition of germination of V. dahliae MS compared to the untreated control, with FO12 being the most effective treatment. Irrigation treatments with Streptomyces strain CBQ-EBa-21 or FO12 were significantly more effective in reducing disease severity and disease progress in olive plants inoculated with V. dahliae compared to the remaining treatments. This study represents the first approach to elucidating the potential effect of Streptomyces strains against VWO.

Escudete, which is caused by Botryosphaeria dothidea, is a disease that is widely distributed in the Mediterranean basin, but is of little general importance. Nevertheless, serious attacks have been observed on occasion, which have caused a considerable reduction in the quality of table olives. The incidence of the pathogen has been associated with damage caused by the olive fly (Bactrocera oleae) and the presence of a possible vector agent, i.e., the midge Prolasioptera berlesiana, whose larvae can feed on fly eggs (although the role the midge may play in the spread of this disease is not well known). Therefore, it is necessary to clarify these interactions to adopt appropriate disease control measures. Studies were conducted in olive orchards planted with the Gordal Sevillana, Picudo, and Hojiblanca olive cultivars. Field surveys were carried out in order to sample their fruits for laboratory analysis, and several bioassays were also performed. Moreover, the population of B. oleae adults was monitored using traps that were baited with food attractants. The results indicated that the three agents developed and evolved in parallel under field conditions. Thus, the midges were attracted by the oviposition punctures caused in fruits by olive fruit flies, regardless of whether the punctures contained eggs. All the investigated olive fruits in which midges were present inside punctures created by olive fruit flies exhibited typical symptoms of escudete, which is necessary for the development of this disease. Forty-eight hours after fly punctures were artificially simulated in the olive fruits, 48.0% of them contained a midge, whereas no midges appeared in the artificially created shapeless wounds in the fruits. This indicates that an olive fly egg is not required for the development of midges; however, they do prefer punctures made by B. oleae. Moreover, when the olive fruits were incubated in a humid chamber, the B. dothidea fungus only appeared in those fruits that contained midges, thus indicating a close relationship between these two agents. Additionally, the midges were able to complete their entire development from egg to adult under controlled conditions, and they fed on the pure cultures of the B. dothidea fungus. Furthermore, although no pathogens were present in the immature midges, some of the pathogens could have been isolated from the inner tissues of the adult female midges. The fact that mycangia is present in the abdomen of P. berlesiana supports the hypothesis that their relationship with B. dothidea may be mutualistic and that they may act as a vector for the fungus.

Reticulitermes grassei is a subterranean termite species that forages on woody structures of the Iberian Peninsula, and is often a building and crops pest. A total of 23 microorganisms associated with the activity of R. grassei were isolated from colonized ecosystems in southern Spain. They were morphologically and molecularly characterized, with fungi being the most prevalent ones. The fungi showed high values of optimum growth temperature, suggesting that they could be able to survive and develop in warm regions. Their cellulolytic activity was tested in carboxymethylcellulose (CMC) agar, concluding that all fungal isolates produce cellulases, and the enzymatic index (EI) was revealed in CMC agar with Gram's iodine solution, with Penicillium citrinum showing the highest EI and Trichoderma longibrachiatum the highest mycelial growth rate on CMC. A preliminary microorganism dispersion assay was carried out with the termites, concluding that these insects may have a positive influence on fungal dispersion and the subsequent colonization of new substrates. Our study suggests that fungi associated with R. grassei may potentially be of interest in biotechnological fields such as biofuel production and the food industry.

Olive anthracnose, a critical olive fruit disease that adversely impacts oil quality, is caused by Colletotrichum species. A dominant Colletotrichum species and several secondary species have been identified in each olive-growing region. This study surveys the interspecific competition between C. godetiae, dominant in Spain, and C. nymphaeae, prevalent in Portugal, to shed light on the cause of this disparity. When Petri-dishes of Potato Dextrose Agar (PDA) and diluted PDA were co-inoculated with spore mixes produced by both species, C. godetiae displaced C. nymphaeae, even if the percentage of spores in the initial spore mix inoculation was just 5 and 95%, respectively. The C. godetiae and C. nymphaeae species showed similar fruit virulence in separate inoculations in both cultivars, the Portuguese cv. Galega Vulgar and the Spanish cv. Hojiblanca, and no cultivar specialization was observed. However, when olive fruits were co-inoculated, the C. godetiae species showed a higher competitive ability and partially displaced the C. nymphaeae species. Furthermore, both Colletotrichum species showed a similar leaf survival rate. Lastly, C. godetiae was more resistant to metallic copper than C. nymphaeae. The work developed here allows a deeper understanding of the competition between C. godetiae and C. nymphaeae, which could lead to developing strategies for more efficient disease risk assessment.

Red leaf blotch (RLB), caused by Polystigma amygdalinum, is considered the most prevalent foliar disease in both traditional and new intensive almond-growing areas in Spain. Since the disease is monocyclic, its control must be based on the reduction of the only source of inoculum-the leaves infected in the previous season and fallen to the ground in autumn. Thus, this study aimed to determine the effect of two microorganisms and urea on RLB inoculum reduction by evaluating different application modes to fallen leaves in field conditions. Leaves of almond cv. Guara showing symptoms of RLB were collected in autumn, placed into nylon mesh bags, and treated by dipping or spraying with conidial suspensions of Myrothecium inundatum or the nonpathogenic strain Fusarium oxysporum FO12. The bags were exposed on the ground or buried in an experimental almond field for 6 months in each experimental year. Bags treated with crystalline urea solution at 46% N or not treated were included as controls. The primary inoculum (number of ascospores per gram of leaf) and the development of fruiting bodies (maturity stages of perithecia) were monitored in the fallen leaves for each experimental treatment combination. M. inundatum significantly reduced the primary inoculum in comparison with the nontreated control or F. oxysporum FO12, showing a similar effect to that observed for urea in the 2 experimental years. The type of application (spraying or dipping) did not show any significant effect, whereas the inoculum was significantly reduced in buried leaves in comparison with leaves maintained on the ground for all the treatments tested. This study represents the first report evaluating management strategies against RLB based on the reduction of the primary inoculum of P. amygdalinum.

Soil-borne pathogens associated with root rot complex diseases cause major yield losses in common bean (Phaseolus vulgaris L.) worldwide. The lack of active ingredients available against these pathogens makes disease control difficult. Seed treatments with Streptomyces spp. have been described as a potential ecofriendly strategy against this complex disease. Here, we evaluate the effect of Streptomyces sp. strains CBQ-EA2 and CBQ-B-8 as biological control agents (BCAs) against root rot complex disease of P. vulgaris, mainly caused by Macrophomina phaseolina and Rhizoctonia solani under natural field conditions in Cuba. To this end, seed treatments with Streptomyces sp. strains CBQ-EA2 and CBQ-B-8, using single or mixed applications, were examined. Seed treatments with the BCA Trichoderma harzianum Rifai A-34 and the chemical Celest® Top 312 FS were included for comparison. In all experimental fields, treatments with Streptomyces spp. had significantly higher efficacy in reducing disease incidence (DI) and disease severity (DS) than the chemical Celest® Top 312 FS, and a similar effect as that by the BCA T. harzianum A-34. Most of the treatments evaluated showed higher germination, quality and yield of legumes than the nontreated control. Seed treatments using the combination of the two actinobacterial strains (Streptomyces sp. CBQ-EA-2+ CBQ-B-8) showed higher effectiveness in reducing DI and DS, and enhancing germination, yield and quality of legumes compared with the nontreated control, with a similar effect as that with the BCA T. harzianum A-34 and the chemical Celest® Top 312 FS. Overall, microbial consortia deserve further research in the future to develop potential biological products for crop protection.

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 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.

The almond ( Prunus dulcis ) constriction canker caused by Diaporthe amygdali is considered one of the most important diseases of this crop in the European continent, especially in the Mediterranean countries. Field surveys conducted in Sicily, Italy, revealed the occurrence of almond trees severely infected by the disease. Symptoms of twig canker, shoot blight and gummosis were widely distributed in almond orchards grown with both local and international cultivars. The highest disease incidence and severity (DI and DS) were observed in the orchards grown with ‘Ferragnes’, ‘Supernova’ and ‘Tuono’ cultivars, whereas those grown with local sicilian cultivars such as ‘Pizzuta’ and ‘Romana’ showed the lowest DI and DS. Laboratory isolations yielded a total of 58 Diaporthe -like isolates. Morphological observations and molecular analysis based on sequencing and phylogenetic analyses of ITS, tef1-α and tub2 gene regions of representative isolates identified the causal agent as D. amygdali . The effect of temperature (5, 10, 15, 20, 25, 30 and 35 °C) was evaluated on mycelial growth rate on PDA and on lesion development in inoculated detached shoots, with the isolates tested showing an optimum growth temperature around 25 and 20 °C, respectively. Pathogenicity tests were conducted by means on detached almond shoots and on potted almonds plants. Results showed that all the isolates were pathogenic in all tissues evaluated showing significant differences in aggressiveness among the isolates. According to our results, this is the most updated study of constriction canker in Italy, including a molecular characterization of D. amygdali , since its first identification in 1936.

Shoot blight and branch dieback of English walnut has been associated with a broad diversity of Botryosphaeriaceae and Diaporthe fungi worldwide. These pathogens affect both wood and fruit tissues, infecting the tree through mechanical or natural wounds. Fruit infections can play an important role in the life cycle of the disease. Thus, the effects of cultivar, and fruit maturity on English walnut fruit infection by Botryosphaeriaceae ( Botryosphaeria dothidea , Neofusicoccum mediterraneum and N. parvum ) and Diaporthe ( Diaporthe neotheicola and Dia. rhusicola ) fungi were evaluated. The infection and disease progress from inoculated attached fruits or by inoculating fruit abscission wounds was evaluated both under laboratory and field conditions. An initial experiment evaluating two inoculation methods was conducted, but there were not significant differences in disease severity between inoculations with mycelial plugs or conidial suspensions. A total of eight cultivars were selected to evaluate their susceptibility to fruit infection, with ‘Chandler’ being the most susceptible for all the pathogens tested compared to the other cultivars. Botryosphaeriaceae showed higher aggressiveness on fruit collected at beginning- or middle summer, while Diaporthe showed similar aggressiveness regardless of fruit maturity stage. Botryosphaeriaceae fungi were able to colonize the entire surface of the inoculated fruit, reaching the peduncle and infecting the attached shoot; while Diaporthaceae fungi were not able to colonize the surface of the inoculated fruit quickly enough to infect the attached shoot before the peduncle was naturally separated from the shoot. Finally, we demonstrated that both Botryosphaeriaceae and Diaporthe fungi can infect shoots by inoculating the natural fruit abscission wounds in the field. This study generates new insights into the influence of fruit infection leading to shoot blight and branch dieback of English walnut caused by Botryosphaeriaceae and Diaporthe fungi.

sterile peat moss (n = 12 per isolate).Plants dipped in sterile distilled water were included as control (n = 12).Chlorotic leaves, wilt and internal wood discoloration were observed on inoculated plants at 3 months after inoculation.No symptoms were observed on controls.The pathogen was consistently reisolated from the basal stem and roots of inoculated plants.Apiospora marii has been reported in olive in Italy, causing tree dieback (Gerin et al. 2020).To our knowledge, this is the first report of A. marii causing wilt, dieback and tree decline in olive in Spain (Farr and Rossman 2022).

Anthracnose, caused by Colletotrichum spp., is the main olive fruit disease. Colletotrichum can severely infect olive fruit with a negative impact on the oil quality. However, the relationship between visible infections of Colletotrichum spp. and olive oil quality is unclear and the influence of latent infections is unknown. This study considers Colletotrichum spp. latent infections and visible infections as factors affecting the quality of olive oil. IAbsorbance in UV (K232 and K270), free acidity, and peroxide index were evaluated in oils from fruit with latent and symptomatic infections by Colletotrichum godetiae of the cvs. Arbequina, Hojiblanca, and Picual. Olive oil samples from i) latent infected fruit at three maturity stages and after two incubation periods and from ii) sets of oils from mixtures of healthy and infected symptomatic fruit were used to determine the impact of the disease on oil quality. Oils from latent infected fruit of cv. Arbequina showed higher acidity than control oils ( P = 0.012). Linear and exponential models were fitted to relate the oil quality parameters to the proportion of symptomatic fruit. Acidity was the most affected parameter, mainly in oils from cv. Arbequina. The thresholds of the percentage of affected fruits causing the loss of category in the quality of the oil varied greatly according to cultivar, with ‘Arbequina’ being the most sensitive.

The effect of mineral nutrition on wilt diseases has been previously reported in many herbaceous hosts, though such an effect on Verticillium wilt in olive (Olea europaea L.; VWO), caused by Verticillium dahliae, is still uncertain. Field observations reveal that nitrogen (N) excess or imbalances of N-potassium (K) favour VWO epidemics. However, this has yet to be demonstrated. Thus, the aim of this study was to evaluate the influences of nutritional imbalances of N and K in V. dahliae infection of olive. To this end, adjusted treatments with N excess (↑N+↑Na), K deficiency (↓K) and their combination (↑N+↑Na+↓K) were evaluated on the viability of V. dahliae microsclerotia (MS), as well as on disease development in olive plants. In parallel, the potential indirect effect of the treatments on the viability of conidia and MS of V. dahliae was evaluated through the stimuli of root exudates. Treatments ↑N+↑Na and ↑N+↑Na+↓K decreased MS germination and disease progress, whereas ↓K significantly increased both parameters. Root exudates from treated plants increased the conidia germination of V. dahliae but reduced the MS germination. The results of this study will be the basis for planning further research towards a better understanding of the effect of mineral nutrition on VWO.