Aflatoxin contamination of almond kernels, caused by Aspergillus flavus and A. parasiticus, is a severe concern for growers because of its high toxicity. In California, the global leader of almond production, aflatoxin can be managed by applying the biological control strain AF36 of A. flavus and selecting resistant cultivars. Here, we classified the almond genotypes by K-Means cluster analysis into three groups (susceptible [S], moderately susceptible [MS], or resistant [R]) based on aflatoxin content of inoculated kernels. The protective effects of the shell and seedcoat in preventing aflatoxin contamination were also examined. The presence of intact shells reduced aflatoxin contamination >100-fold_. The seedcoat provided a layer of protection but not complete protection. In kernel inoculation assays, none of the studied almond genotypes showed a total resistance to the pathogen. However, nine traditional cultivars and four advanced selections were classified as R. Because these advanced selections contained germplasm derived from peach, we compared the kernel resistance of three peach cultivars to that shown by kernels of an R (Sonora) and an S (Carmel) almond cultivar and five pistachio cultivars. Overall, peach kernels were significantly more resistant to the pathogen than almond kernels, which were more resistant than pistachio kernels. Finally, we studied the combined effect of the cultivar resistance and the biocontrol strain AF36 in limiting aflatoxin contamination. For this, we coinoculated almond kernels of R Sonora and S Carmel with AF36 72 h before or 48 h after inoculating with an aflatoxin-producing strain of A. flavus. The percentage of aflatoxin reduction by AF36 strain was greater in kernels of Carmel (98%) than in those of Sonora (83%). Cultivar resistance also affected the kernel colonization by the biological control strain. AF36 strain limited aflatoxin contamination in almond kernels even when applied 48 h after the aflatoxin-producing strain. Our results show that biocontrol combined with the use of cultivars with resistance to aflatoxin contamination can result in a more robust protection strategy than the use of either practice in isolation.

The species Carissa grandiflora A. DC., commonly called Natal plum, is a shrub native to the coastal region of Natal, South Africa. In southern Spain, Natal plum is used as an ornamental plant due ...

Anthracnose, the most critical fruit disease affecting olive crops, necessitates the evaluation of the susceptibility of traditional and new varieties. In Spain and Portugal, anthracnose is caused by several Colletotrichum species, with C. godetiae and C. nymphaeae being dominant and C. acutatum and C. fioriniae being secondary. This study explores the susceptibility of fruits from an F₁ progeny resulting from a cross between ‘Picual’ (resistant) and ‘Arbequina’ (moderately susceptible) cultivars to C. godetiae. While most genotypes showed resistance levels comparable to their parents, seven showed a 50% reduction in disease severity compared with ‘Picual.’ The normal distribution of genotypes’ response to the pathogen suggests a complex resistance mechanism. Furthermore, we assessed the susceptibility of four traditional cultivars, two new cultivars (‘Sikitita-2’ and ‘Martina’), and five advanced selections (pre-commercial genotypes) to C. godetiae and C. nymphaeae. Despite the significant interaction between the olive genotype and Colletotrichum species in this experiment, the new cultivars and advanced selections were classified as susceptible or moderately susceptible against both species. A subsequent analysis of the interaction between ‘Picual’ (resistant) and ‘Hojiblanca’ (susceptible) fruits with the four mentioned Colletotrichum species revealed significant differences among cultivars but no interaction between genotype and pathogen species. Colletotrichum species were categorized as follows: (i) C. godetiae and C. nymphaeae as highly virulent, (ii) C. acutatum as moderately virulent, and (iii) C. fioriniae as weakly virulent. Finally, C. nymphaeae exhibited an enhanced ability to infect and develop acervuli in olive leaves, potentially serving as an inoculum source for this species. The absence of a correlation between leaf and fruit susceptibilities to the pathogen suggests differences in resistance mechanisms. In conclusion, this study provides valuable insights into the complex interactions between olive genotype and Colletotrichum species, essential for cultivar selection and understanding the disease cycle.

Aspergillus species grow saprophytically on plant debris, releasing conidia that occasionally contaminate nut crops with hepatocarcinogenic aflatoxins (AFs), specifically types B (B1 and B2) and G (G1 and G2). While A. flavus and A. parasiticus are recognized as prominent producers of AFs, A. minisclerotigenes has emerged as a significant threat in Spanish pistachio orchards, accounting for 7% of the 76 Flavi strains collected from 2019 to 2021. Morphological and molecular analyses confirmed the taxonomic status of A. minisclerotigenes, which occupies an intermediate phylogenetic position between A. flavus and A. parasiticus. This species can be easily isolated from pistachio nuts on the tree canopy, underscoring the potential risk it presents. Growth studies established that A. minisclerotigenes is thermophilic, thriving at temperatures between 30 and 35°C and tolerating low water activity (a _w = 0.88). This species exhibited an extraordinary mycotoxigenic capacity, producing AF levels 170 times higher than A. parasiticus and 2,149 times higher than A. flavus. A. minisclerotigenes produced predominantly AFG, followed by AFB1, with significant interstrain variation. AF biosynthesis peaked at 25 to 30°C, with strains producing up to 335 g/kg of total AFs. These findings highlight A. minisclerotigenes as a critical concern for European nut production, exacerbated by warming climatic trends, underscoring the urgent need for enhanced surveillance and targeted management strategies to mitigate contamination risks.

The common fig (Ficus carica L.) is susceptible to mycotoxin contamination, raising food safety concerns given the strict maximum levels for aflatoxins (AF) and ochratoxin A (OTA) established by Regulation (EU) 2023/915 for dried figs. We characterized the susceptibility of three commercially relevant cultivars from the Jerte Valley (‘Calabacita’, ‘Cuello Dama Blanco’, and ‘Granito’) to Aspergillus section Flavi colonization under controlled and orchard conditions. These findings were integrated with an industry surveillance dataset (2014–2023; 326 batches), with cultivar comparisons restricted to the comparable period 2020–2023 (184 batches), from a local fig-processing cooperative. Under controlled inoculation, ‘Calabacita’ consistently showed the highest internal colonization and proportion of figs colonized, whereas ‘Granito’ showed the lowest values. Sealing the ostiole reduced colonization across cultivars and abolished cultivar differences, thereby supporting the ostiole as the primary entry route. Fruit susceptibility increased with fruit size across all three cultivars. Dry conidial inoculation, emulating natural airborne spread, resulted in substantially higher colonization than inoculation with an aqueous conidial suspension, both in severity (100% vs. 3.7%) and incidence (100% vs. 7.3%). Orchard assays were consistent with the controlled inoculation results: ‘Calabacita’ showed higher section Flavi colonization than ‘Cuello Dama Blanco’ and ‘Granito’, which did not differ from each other. Fruit position did not affect colonization by section Flavi, but it significantly affected colonization by section Nigri, which was higher in dropped fruits across cultivars. AF-OTA co-occurrence was restricted to ‘Granito’ (3 batches; 2.6%) and was absent in ‘Calabacita’. Surveillance data (2020–2023) were consistent with the experimental findings. ‘Calabacita’ showed predominantly AF-related non-compliance (with AFB₁ and AFTA exceedances reaching 25.7%), whereas ‘Granito’ showed higher OTA exceedance (10.5% vs. 1.4%), reflecting distinct contamination profiles between cultivars. This study informs AF and OTA management strategies in dried figs based on cultivar susceptibility profiling, prescreening systems prior to commercialization, and reduction in fruit–soil contact during drying.