Extensive damage to more than 1000 plant species, including food crops, oil crops, vegetables, fruit trees, garden timbers, ornamental plants, fodder, and weeds, has been caused by emerging phytoplasma-mediated diseases, thereby threatening global food security. Many factors, including environmental changes, invasion routes, transmission trials, and the emergence of new pathogen lineages, contribute to the spread of phytoplasma-related plant diseases. Stable and long-term solutions to improve plant health are required to manage many phytoplasma plant diseases effectively. A new strategy to tackle these critical issues includes critical assessment of losses, climate change, predictive modelling, disease surveillance, and improved detection techniques that target the phytoplasma. Herein, we review phytoplasma-associated plant diseases, emerging phytoplasma pathogen threats, factors contributing to their spread, and methods for surveillance and detection. In addition, case studies and global collaborative efforts are discussed. The review also provides insights into future research directions on plant diseases caused by phytoplasmas for their effective management.

Sugar beet root damage at harvest promotes sucrose losses of circa 0.1 - 0.4 % day-1 in storage. However, root response to environmental stresses at harvest and their consequential rates of damage are not known. We investigated the effects of temperature and water stress at harvest on root resilience to damage and tissue strength. Water (irrigated to field capacity and non-irrigated) and temperature (cold and mild) treatments were imposed on physiologically mature sugar beet plants for seven weeks prior to and for three days after harvesting, respectively. Water status at harvest significantly affected relative water content (RWC) (p < 0.001), root weight (p < 0.001) and root width (p < 0.001). RWC was positively correlated to surface damage (R2 = 0.43, p = 0.02), root tip damage (R2 = 0.42, p = 0.03), tissue compression (R2 = 0.41, p = 0.05), and tissue puncture (R2 = 0.46, p = 0.01). Tissue damage was not affected by root tissue temperature of 4 °C compared to 12 °C. We conclude that sugar beet damage at harvest is not influenced by root temperatures over the range commonly observed in the UK and temperate production areas. However, higher water status at harvest, such as would be observed in a wet season, increases root tip and surface damage. These findings will help to inform optimum harvesting conditions to minimise sugar loss from the sugar beet crop.