Mineral Nutrition of Vegetable and Herb Diseases

Mineral nutrition directly affects the health of plants. There are many situations where the susceptibility of the plant to disease solely becomes a function of the nutritional status of the plant. Nutrition is closely tied to all three aspects of the disease triangle: host, pathogen, and environment. Nutrition can alter disease development by boosting resistance mechanisms in the host, by affecting the nutrition and/or reducing virulence of the pathogen, and by altering the soil environment to make the rhizosphere more disease suppressive or conducive. Many plant defense reactions result from the enzymatic production of physical and biochemical products (e.g., lignin, suberin) that require mineral elements as cofactors and/or activators. Toxic-free radicals produced during the disease process are quickly detoxified by Fe-, Cu-, Mn-, and Zn-based dismutases. The speed in which a plant can respond to disease is often governed by the nutritional status of their tissue/cells. This chapter outlines the individual roles of essential and beneficial elements in manipulating the disease status of vegetables and herbs. Selected examples have been highlighted for 20 elements where their application was shown to suppress vegetable and herb diseases and include nitrogen, phosphorus, potassium, calcium, magnesium, sulfur, chlorine, iron, manganese, copper, zinc, boron, molybdenum, and nickel along with beneficial elements aluminum, cerium, lanthanum, selenium, silicon, and titanium.