A Multiple Component Approach to Manage Citrus Diseases for Optimum Productivity

Recognition of how nutrition interacts to suppress disease conducive, and enhance non-conducive factors of the plant, pathogen, and environment facilitates the development of a disease control strategy that maintains optimum health, vigor, and productivity of citrus.   Effective nutrient management can ameliorate both abiotic and biotic stresses to favor productivity by increasing plant pest resistance and suppressing disease.  Weed control, an important aspect of grove management, may induce a nutrient deficiency since herbicides are mineral chelaters and often toxic to soil microorganisms that make minerals available for plant uptake. Virulence of many plant pathogens involves immobilization of plant-essential nutrients important in disease response through toxins or extracellular enzymes.  Management or pathogen-induced nutrient deficiency can predispose plants to severe disease. There are a multitude of potential citrus diseases to consider in developing an effective nutrient management plan.  This presentation will discuss principles of nutrient management for effective disease control with examples of their effective implementation in Brazil and the United States citrus growing areas to control diseases such as HLB, CVC, blight, black dot, and canker. Key aspects of these nutrient management plans include alternative weed control methods, timely compensation for disrupted nutrient functions and distribution in the plant, and systemic mobility of key nutrients to stimulate host resistance and suppress pathogenesis. These studies demonstrate that management techniques and cultural practices that manage nutrient sufficiency can provide effective weed and disease control for HLB, blight, CVC, black-dot, canker and other citrus diseases to maintain efficient citrus productivity.