http://hdl.handle.net/10174/997 2026-04-04T13:29:20Z http://hdl.handle.net/10174/40240 Title: Fertigation with nitrogen and other nutrients in northern highbush blueberry Authors: Bryla, David; Machado, Rui; Leon-Chang, D.P.; Orr, S:T. Abstract: Most highbush blueberry (Vaccinium sp.) fields are irrigated by drip. A major advantage of drip is the ability to fertigate and apply fertilizers directly through the irrigation water. A series of studies were conducted in western Oregon, USA to identify the best practices for applying N and other nutrients by fertigation. Fertigation with various fluid NH4-N sources, including ammonium sulfate, urea, and urea sulfuric acid, produced more growth and greater yield than conventional granular fertilizers in ‘Bluecrop’ blueberry. Furthermore, applying humic substances in combination with N fertigation nearly doubled root production during the first 2 years after planting. To apply other nutrients, soluble potassium sulfate and potassium thiosulfate are good sources for fertigation in blueberry. Both fertilizers had an immediate effect on availability of K and other nutrients in the soil solution and after 2 years increased the nutrient status of ‘Duke’ blueberry. However, whether applied by fertigation or as a granular product, there was no benefit to fruit production at sites with sufficient soil K. Phosphorus fertilizers also had no effect on mineral nutrition or fruit production, even under P-limited conditions, in ‘Duke’ or ‘Bluecrop’. In this case, the soil was high in clay and likely bound much of the P. The use of B fertilizers, on the other hand, increased the concentration of B in the leaves and fruit of ‘Earliblue’ and ‘Elliott’ blueberry, particularly when it was applied by fertigation or as a foliar fertilizer. Fertigation with Ca products, including micronized gypsum and calcium thiosulfate, had little effect on Ca in the leaves or fruit of ‘Duke’, ‘Earliblue’, ‘Bluecrop’, or ‘Aurora’ but increased fruit firmness of ‘Elliott’ blueberry, particularly in cold storage. Given its potential benefits on fruit quality, we will continue to test fertigation with Ca fertilizers in conventional and organic blueberry fields. 2025-12-20T00:00:00Z http://hdl.handle.net/10174/40239 Title: Metabarcoding Analysis Reveals Microbial Diversity and Potential Soilborne Pathogens Associated with Almond Dieback and Decline Authors: Albuquerque, André; Patanita, Mariana; Amaro Ribeiro, Joana; Campos, Maria Doroteia; Santos, Filipa; Monteiro, Tomás; Basaloco, Margarida; Félix, Maria do Rosário Félix Editors: Guo, Jianwei; Yang, Honglan; Wang, Xiaolin Abstract: Almond decline and dieback have become significant challenges in newly established orchards, with symptoms including internal necrosis, canker, and external gummosis. This work aims to explore the potential fungal and bacterial causative agents through metabarcoding and traditional culture plate isolation across six almond cultivars. Our results emphasize the multifactorial nature of almond decline and dieback, with possible co-infections by opportunistic fungi and bacteria playing a central role. Classical isolation identified 47 fungal species or genera, including Diaporthe amygdali, Diplodia corticola, Phytophthora sp., and several Fusarium species. Almond metabarcoding revealed a more diverse microbial community, highlighting the prevalence of soilborne pathogens such as Neocosmospora rubicola, Dactylonectria estremocensis, and Plectosphaerella niemeijerarum. Soil metabarcoding suggested that these pathogens likely originate from nursery substrates or soils shared with other crops, such as olives and vineyards, that serve as a source of inoculum. ‘Soleta’ generally presented lower richness when compared to the other tested cultivars, suggesting a higher degree of biotic stress and decreased plant resilience. This study highlights the value of integrating NGS approaches to comprehensively study complex diseases and the need for further research on pathogen interactions and cultivar susceptibility for the future development of new sustainable, targeted management strategies in almond orchards. 2025-07-25T23:00:00Z http://hdl.handle.net/10174/40237 Title: Transcriptome profiling of symptomatic vs. asymptomatic grapevine plants reveals candidate genes for plant improvement against trunk diseases Authors: Patanita, Mariana; Campos, Maria Doroteia; Albuquerque, André; Amaro Ribeiro, Joana; Pimentel, Diana; Ramiro, Ricardo; Monteiro, Tomás; Basaloco, Margarida; Santos, Filipa; Castro, Isaura; Félix, Maria do Rosário Abstract: Abstract Background Grapevine trunk diseases (GTDs) are a disease complex that pose a serious challenge to vineyard productivity worldwide. Their increasing occurrence, coupled with the absence of effective treatments, turns their incidence one of the biggest obstacles to viticulture. A deeper understanding of grapevine defence mechanisms is essential to develop new strategies for a sustainable disease management. Results This study explored the transcriptome profiling of GTDs symptomatic and asymptomatic plants of ‘Trincadeira’ (a slightly susceptible or tolerant cultivar to GTDs) and ‘Alicante Bouschet’ (a highly susceptible susceptible or susceptible cultivar to GTDs), under natural field conditions. RNA-seq yielded 1 598 differentially expressed genes (DEGs) when comparing cultivars, and 64 DEGs associated with symptomatology, regardless of the cultivar. Transport was revealed as the main biological process involved, predominantly activated in ‘Alicante Bouschet’, indicating a possible link between these genes and disease progression. Conversely, the relative tolerance of ‘Trincadeira’ to this disease complex might be supported by the activation of secondary and hormonal metabolism and the differential expression of a set of defence-related genes, which may act as key factors to limit GTDs infection. An important role of the peroxidase gene PER42 in the inhibition of GTDs symptoms was highlighted in this study. Conclusions Our results provide novel insights into grapevine resistance mechanisms to GTDs and highlight candidate genes for improving disease tolerance. To the best of our knowledge, this is the first transcriptomic study of naturally infected grapevines with multiple trunk pathogens under natural field conditions. By modulating the activation or inhibition of key plant response regulators, it may be possible to enhance resistance, offering sustainable and effective strategies for successful management of GTDs. 2025-07-01T23:00:00Z http://hdl.handle.net/10174/40235 Title: First report of Biscogniauxia mediterranea causing cankers on almond trees (Prunus dulcis) Authors: Faustino, Ana; Marinho, Cláudia; Oliveira, M. Margarida; Félix, Maria do Rosário; Marum, Liliana Editors: Úrbez Torres, José R. Abstract: Biscogniauxia mediterranea is the causal agent of charcoal disease in Quercus suber, the main species of the dynamic ecosystem, known as “Montado”, in the Alentejo region, Portugal. In the last years, almond orchards have been introduced in this region due to water availability through the Alqueva dam and the possibility of mechanical harvest. The high-density planting associated with mechanized harvesting and irrigation systems observed in these new orchards can potentiate the appearance of new diseases. In a survey conducted in March 2022, symptomatic diseased trees from Soleta and Vairo cultivars were detected in Beja, Portugal. From this material, we have isolated numerous cultures and could identify B. mediterranea from all individuals analyzed by molecular and morphological techniques. Pathogenicity tests were performed in almond plant material and successfully reisolated from lesions, confirming Koch’s postulates. Phylogenetics analyses demonstrated the similarity between our sequences and sequences from Quercus suber worldwide. To our knowledge, this is the first report of B. mediterranea causing diseases on almond trees (Prunus dulcis) in Portugal and worldwide. 2025-09-08T23:00:00Z