Interactions between plants, nutrients, and disease pathogens are very complex and not completely understood. Nutrition, although frequently unrecognized, has always been a primary component of disease control. Most soils and environments where plants are cultivated contain an abundance of disease pathogens. On the most basic level, plants suffering a nutrient stress will be less vigorous and more susceptible to a variety of diseases. In this respect, all nutrients affect plant disease. However, some nutrient elements have a direct and greater impact on plant diseases than others. This paper discusses the more significant nutrients and their interactions with disease.
Disease resistance in plants is primarily a function of genetics. However, the ability of a plant to express its genetic potential for disease resistance can be affected by mineral nutrition. Plant species or varieties that have a high genetic resistant to a disease are likely to be less affected by changes in nutrition than plants only tolerant of diseases. Those that are genetically highly susceptible will likely remain susceptible with nutritional regimes that greatly improve the disease resistance in less susceptible or tolerant plants. As Dr. D. M. Huber states “It is clear that the severity of most diseases can be reduced and the chemical, biological, or genetic control of many plant pathogens enhanced by proper nutrition”. Fertilizer recommendations are developed to optimize nutrient uptake and provide the crop with adequate nutrients for normal growth and yield. In most situations, this level of nutrients will also be sufficient to enable the crop to maximize disease resistance. However, there are cases where nutrient applications higher than needed for optimum growth can result in improved disease resistance.