Devastating crop diseases could be controlled by large-scale aerial scanning, which saves billions of dollars worth of lost plants every year, a team of British researchers have discovered. An estimated 16 per cent of crops such as olives, coffee, almonds, citrus and grapevines are destroyed every year by virulent diseases. The research, which was led by Prof Pablo Zarco-Tejada, reveals that new large-scale aerial crop-scanning methods can achieve up to 92 per cent accuracy in detecting one of the diseases, the <i>Xylella fastidiosa</i> (Xf) pathogen. The <i>Xf</i> pathogen is one of the greatest threats to crops, causing dieback, browning and loss of leaves, reduced fruit size and plant death and is a threat to at least 550 species worldwide. In the olive sector alone it has led to losses of up to €5.2 billion ($5.88 billion) a year with tens of millions of trees destroyed under official eradication schemes. Because of its capacity to mutate and colonise a wide range of cultivated plants, <i>Xf</i> is universally regarded as a "<a href="https://www.eppo.int/ACTIVITIES/plant_quarantine/A2_list">quarantine organism</a>", a pest that has to be contained and possibly eradicated because of the danger it poses to the world's agriculture. Since 2013, <i>Xf</i> has been detected in France, Spain and Portugal and in 2019 it was also discovered in Israel, announcing its arrival in the Middle East. Swansea University researchers from the department of geography were part of an international team of experts from the University of Salford, the University of Melbourne, the Spanish National Research Council and the European Commission that scanned one million infected and healthy trees in seven regions across Europe. Using advanced imaging technology – known as hyperspectral imagery – and thermal imaging they were able to detect infectious plant diseases caused by the <i>Xf</i> pathogen before symptoms became visible. Swansea University researcher Alberto Hornero says the research, published in <i>Nature Communications</i>,<i> </i>could help eradicate the disease. "This new research is a step forward in large-scale hyperspectral screening for <i>X</i>f detection," he said. "We can now pinpoint with great accuracy the crops being affected by the <i>Xf</i> pathogen rather than by other environmental causes, before any symptoms appear. "In the future this could allow for more timely containment and elimination action to be taken to protect crops, which can help reduce the impact that <i>Xf </i>has on the environment and economy worldwide.” The UK team focused on the development and setting up of radioative transfer models and participated in field work and airborne data collection. Since there is <a href="https://www.thenationalnews.com/world/deadly-olive-tree-disease-across-europe-threatens-95-per-cent-of-crops-1.1005989" target="_blank">no known cure for the diseases</a> caused by <i>Xylella fastidiosa</i>, there are only three pest management strategies available at the moment: exclusion, preventing it from reaching new areas; eradication, through the destruction of any newly infected plants; and containment, aimed at preventing its spread beyond affected areas. All of these strategies are based on monitoring all host plants to detect any new outbreak as soon as possible. In 2020, a US study said that over the next 50 years the pathogen could destroy olive crops in Italy, Spain and Greece – which together account for 95 per cent of the world's olives.
