Influence of the environment and nutrition on the fatal yellowing of palm oil and powdery mildew of eucalyptus

Abstract

Several factors can influence the progress of the disease, including the environment and plant nutrition. The climate plays a fundamental role in the metabolism of the pathogen and the host, and may or may not favor the greater intensity of the disease. Thus, quantifying these variables is essential to relate them to the spatial and temporal progress of the disease and define management strategies. Furthermore, to understand the origin and quantity of the initial inoculum, the pathogen dissemination mechanism and the pathosystem behavior, it is also necessary to study the temporal progress. Subsequently, the correct and balanced nutrition of the plants must always constitute the first line of defense against pathogens. Micronutrients are able to mediate the activation of plant defense products when available in adequate and balanced amounts in plant tissue. Different sources of these micronutrients and non-essential but beneficial elements are being evaluated around the world to verify their effect in reducing the intensity of diseases. Therefore, this study aimed to evaluate the influence of environmental variables and to evaluate the plant's miniral nutrition on the temporal progress of Fatal Yellowing of oil palm and powdery mildew of eucalyptus. The result of this research was divided into three articles. The first aimed to evaluate the relationship between the incidence of fatal yellowing in oil palm with the nutritional status of the plant, soil class and fertility and climatic variables. Checking if, after all the analyzes carried out, the soil and climate conditions generated water accumulation in certain soil classes, which are related to the Fatal Yellowing of oil palm, causing a deficit in plant nutrition. This hypothesis was also confirmed by proteomic analysis, which identified the environmental stress conditions of roots in plants with symptoms. Under these conditions, several pathogens, both in the soil and in the shoot, may be opportunistic and associated with the observed symptoms, but may not be the primary cause of the disease. The second article aimed to study the disease severity over time and adjust nonlinear models to the temporal progress of eucalyptus powdery mildew in a mini clonal garden. It was concluded that the use of clones with lower intensity of the disease can reduce the losses by powdery mildew in eucalyptus and thus increase the production of cuttings. The third article aimed to select nanoparticles for the management of eucalyptus powdery mildew. Boron, silver and silicon nanoparticles significantly reduced the severity of the disease compared to the control. Thus, the potential of adequate nutrition in the management of plant diseases was verified.