Technical Abstract: It has long been recognized that mineral nutrition of host plants affects resistance to plant diseases or maladies, yet agricultural practitioners often exclude micronutrients as a husbandry strategy component even though their importance to plants for counteracting maladies, disease causing organisms, and facilitating normal plant growth and development is commonly recognized. This general disregard is especially true for nickel (Ni), the essential plant nutrient element to which the vast majority of practitioners are typically least concerned or aware. This lack of attention to Ni is largely because the amount needed to prevent deficiency is minuscule and almost all soils contain far more Ni than is typically thought necessary for satisfying plant needs. For many crop species, Ni is more appropriately described as a pico- rather than a micronutrient. The relative number of Ni atoms per unit of plant tissue is the lowest of all known essential mineral elements, with the possible exception of molybdenum. Because Ni's role as an essential mineral element in plants is a relatively recent discovery and its deficiency in real-world crop production systems was only recently documented, little is known about Ni related maladies and interactions with disease pathogens and the potential for usage of Ni as a form of biological control of microbial pests. This publication reviews the interaction of Ni with plant maladies or disease within the context of Ni deficiency. Information is presented that indicates that nickel is a key factor affecting production of secondary plant metabolites, and thus influencing plant resistance to diseases.