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Zarcos Duarte, Beatriz

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  • Citrinos na Dieta Mediterrânica: frutos com sumo e com história
    Publication . Matias, Pedro; Duarte, Beatriz; Duarte, Amílcar
    Os citrinos são muito importantes para as populações mediterrânicas, do ponto de vista económico e social. A diversidade dos citrinos é encantadora, tal como a história da sua chegada à Europa. São originários da Ásia, mas existem no Mediterrâneo desde a Grécia Antiga. Atualmente, “tropeçamos” neles: plantamo-los nos nossos quintais, nas ruas das nossas cidades, em parques e jardins e produzimo-los em pomares com elevada qualidade. Usamos os seus frutos em muitos pratos que confecionamos e usufruímos dos seus enormes benefícios para a saúde.
  • Citrus aphids in Algarve Region (Portugal): Species, hosts, and biological control
    Publication . Paiva, Paulo Eduardo Branco; Neto, Luis; Marques, Natália; Duarte, Beatriz; Duarte, Amilcar
    Aphids affect citrus by causing leaf deformations and reducing fruit production. Additionally, aphids are a great concern due to their ability to transmit Citrus tristeza virus (CTV), the cause of tristeza, one of the main citrus diseases. In the last four years, citrus orchards in the south of Portugal (Algarve region) were sampled for aphid species identification and counting. Aphis spiraecola was the most abundant species, representing more than 80% of all identified aphids, and the damage (leaf deformation) it causes was directly proportional to its density. A. gossypii was the second most common species, followed by A. aurantii and Macrosiphum euphorbiae. The number of aphids in nymph stages was predominant over the adult stages (both wingless and winged) in all species. A. citricidus, the most efficient CTV vector, was not detected. The largest populations of A. spiraecola were observed in lemon and orange trees during spring (>100 individuals per shoot), with great damage observed in orange, lemon, and mandarin trees. A. gossypii was observed mainly in mandarin and tangor trees. There was a low activity of natural biological control agents, with the parasitism of A. spiraecola by Lysiphlebus spp. and Binodoxys spp. ranging from 0.3 to 1.5%. The numerical ratio ranged from 150 to 440 aphids per predator, and among these, syrphids were the most abundant, followed by lacewings and coccinellids (Scymnus).
  • HLB e a psila-africana-dos citrinos: um novo problema e novas soluções
    Publication . Magalhães, Tomás; Duarte, Beatriz; Poeira, Rita; Neto, Luís; Marques, N T.; Duarte, Amilcar
    Os citrinos são uma cultura importante na Península Ibérica, fazendo parte da dieta mediterrânica e contribuindo para a economia dos dois países. Atualmente a citricultura desta região está ameaçada por uma doença devastadora, o huanglongbing, uma vez que a psila-africana-dos-citrinos, vetor da bactéria que causa esta doença, já se encontra em quase toda a região costeira de Portugal e também no norte de Espanha. A bactéria não foi até agora detetada, mas para travar o vetor, tem sido usada a luta biológica com um parasitóide da psila. A gravidade desta ameaça à nossa citricultura obriga a que se adotem novas abordagens de proteção fitossanitária, incluindo estratégias coletivas, abrangendo várias explorações agrícolas.
  • Effect of ground cover on soil carbon storage in a citrus orchard: challenges and preliminary results.
    Publication . Reis, Adélia; Duarte, Beatriz; Duarte, Amilcar
    Fruit tree crops, as a relevant agricultural sector, have great importance in the sequestration of atmospheric carbon and its stock in the soil. A vast area of citrus orchards is found in the Mediterranean region, an area prone to soil degradation and desertification. Adoption of sustainable agricultural practices, such as permanent soil cover in orchards, can contribute to maintaining their productivity, protecting them from erosion, increasing the level of organic matter and increasing the stock of organic carbon. This study aimed to determine the organic carbon stored in the soil up to 20 cm depth in citrus orchards under different soil management systems. An experiment was carried out in a ‘Nadorcott’ mandarin orchard where measurements were performed both in the tree rows (between the trees in the ridges) and in the inter-rows (between ridges). Two treatments were tested: A) tree row without ground cover and inter-row covered with spontaneous herbaceous vegetation and B) tree row with almond shell mulching and inter-row with a permanent cover of sown herbaceous vegetation. Soil organic matter varied between 1.97 ± 0.14 % in the tree row without ground cover and 4.68 ± 0.03 % in the inter-row with spontaneous vegetation cover. Regarding the organic carbon stocked in the soil of the orchard, mean values of 25.04 ± 1.15 Mg C ha-1 were obtained in treatment A) and 31.24 ± 3.98 Mg C ha-1 in treatment B).
  • Current distribution of the African citrus psyllid Trioza erytreae in Portugal: relation to climatic conditions
    Publication . Duarte, Beatriz; Poeira, Rita; Magalhães, Tomás; Paiva, Paulo; Soares, Celestino; Neto, Luís; Marques, Natália; Duarte, Amilcar
    The onset of Trioza erytreae, the African citrus psyllid, in the northwest of the Iberian Peninsula (north of Portugal and northwest of Spain) caused great concern among citrus growers in Europe. This insect is a vector of the bacteria Candidatus Liberibacter spp., the causal agent of huanglongbing, one of the most devastating citrus diseases. The first report of T. erytreae presence in mainland Europe refers to an area with isolated citrus trees and no significant citrus orchards. However, it was predictable that T. erytreae could spread quickly reaching the most important citrus growing area, in the south. Therefore, the Portuguese citrus industry is the first to be threatened in Europe, but the entire European citrus industry is at risk. In addition to the containment measures taken by the Portuguese and Spanish Phytosanitary Services, several models were made to predict how the African citrus psyllid could advance through the territory of the two countries. Releases of the parasitoid Tamarixia dryi were used for psyllid control. Despite that, T. erytreae has moved south and is on the verge of reaching the most important Portuguese citrus-producing area, which is connected to the citrus-growing areas of the other Mediterranean countries. This advance took place along the coast, without reaching interior regions of the country, where, according to some models, a high-water vapor pressure deficit hinders the insect's development in warmer areas. Populations of T. erytreae dropped significantly in 2021 and 2022, making it difficult to detect even in previously infested areas. This doesn't give farmers peace of mind because the presence of T. erytreae, even in low populations, could lead to a quick spread of huanglongbing, if or when the disease arrives in Europe. Therefore, it is crucial to continue to monitor T. erytreae populations and implement the necessary containment measures for the vector.
  • Effects of a severe recovery pruning in the productivity and fruit quality of two late orange cultivars
    Publication . Matias, Pedro; Duarte, Beatriz; Mendonça, Angélica; Oliveira, Silvino; Barrote, Isabel; Guerrero, Carlos; Duarte, Amilcar
    Currently, citrus production plays a major role in worldwide agriculture, especially in the Mediterranean. However, the typical irregular branch development and the formation of large canopies and dense exterior foliage can be significant limitations to light entry and air circulation through the canopy. Consequently, dead branches appear in the inner canopy, which becomes unproductive; flowering and vegetative growth occur only on the outer canopy, and the fruits formed usually are of lower quality. Furthermore, dead branches can be an inoculum for some pathogenic microorganisms, chemical treatments become less efficient since reaching the inner canopy branches becomes more difficult, and fruit harvest becomes harder and more expensive. Pruning is a cultural practice that allows canopy management and the control of the problems mentioned above. However, many citrus growers avoid or postpone pruning, or prune insufficiently due to pruning’s high costs and, sometimes, direct production losses. To assess the effects of pruning, two experiments were performed on large canopy trees: one in ‘Valencia Late’ and the other in ‘Dom João’. In both experiments, some trees were left unpruned (control) and others were severely pruned in November 2019 (recovery pruning). The pruning was made by removing at least 30% of the canopy, with the complete removal of a few large branches. Pruning allowed a significant increase in light availability inside the canopy. In the 2020 harvest, there were no differences in fruit size between treatments. The production decreased in the pruned trees in the ‘Dom João’ experiment, as expected, and was similar in the ‘Valencia Late’ experiment. In the 2021 harvest, in both experiments, the pruned trees had a smaller canopy, and the production was similar in both treatments. However, the fruits from pruned trees were bigger in the ‘Dom João’ experiment and several quality parameters were better in the ‘Valencia Late’ experiment.