This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: Xylella fastidiosa is a pathogen that poses a serious threat to agri-food systems. An insect-borne bacterium that eventually causes trees to dry out and die, it was first detected in Spain in 2016, alarming the farming community.
Although it is more commonly associated with olive trees, it also inflicts heavy losses on almond crops. Since 2017, there has been a high incidence of the disease in almond trees in the Alicante area, where it is resulting in major economic losses by reducing harvests and killing trees. Studies to date had focused on detecting the pathogen and biological control, and the main way of managing infected trees has been eradication.
Previous studies focused solely on the crop—in this case, almond trees—without taking the rest of the surrounding environment into account. Thus, a team led by the ERSAF research group at the University of Córdoba carried out a study that broadens the focus to the landscape scale, taking into account the interactions that occur within the ecosystem. The work is published in the journal NeoBiota.
"The aim of our work was to assess how infection by Xylella fastidiosa, environmental factors and adjacent vegetation jointly influenced the impact of the pathogen on almond crops," explained Ricardo Hernández, lead author of the study. After gathering information on the plant health status of almond trees on 19 plots located in an area of Alicante with a major Xylella outbreak, the team also sampled the natural surroundings, taking into account the type and condition of the surrounding shrubs, as well as the climatic factors in the area. This landscape-scale approach made it possible to identify environmental and biological relationships between the different elements of the landscape and how these shaped the impact of the disease, showing that it is driven by a combination of factors rather than by the effect of the pathogen alone.
"We observed that a greater presence of shrub species, acting as reservoirs of the pathogen (rockrose, gorse and buckthorn) and carrying high pathogen loads, was linked to a greater impact of infection on the almond trees," the researcher noted. This showed that, contrary to what is commonly believed, the natural environment does not, in these cases, act as a buffer against the effect of pathogens on crops. According to the study, the most important factor aggravating the impact of the disease was water stress.
Temperature and lack of water influenced the severity of infection in both the almond trees and the adjacent shrubland, demonstrating the importance of climate. When it comes to managing Xylella fastidiosa in almond trees, this study—the result of a collaboration between the University of Córdoba's ERSAF and Agricultural Entomology groups, the Institute for Sustainable Agriculture (IAS-CSIC) and the Doñana Biological Station—provides new insights. In light of these findings, management and surveillance efforts should prioritize orchards located in high-risk settings, particularly those in fragmented, drought-prone landscapes featuring extensive cover of pathogen-hosting shrubs in the adjacent vegetation.
Extract — continue reading at the source.
