CO-PI
Development of root nutrient and fertilization guidelines for HLB-affected orange and grapefruit
Root structure and function is an understudied component of citrus research in the age of Huanglongbing (HLB) disease. A better understanding of how roots are affected by HLB can potentially lead to better management options in the future. Fertilization guidelines utilize leaf nutrient concentrations to generate a fertilizer recommendation for N, P, K, Ca, Mg, and micronutrients. These guidelines were developed in pre-HLB times and may no longer be valid. There are currently no guidelines for optimal nutrient concentrations in healthy roots, and a disconnection in assessing how healthy trees are benefitting from current nutrient management strategies. Our objective is to conduct field trials using variable rate nutrient fertilization to determine optimal nutrient concentrations in leaves and roots, and relate these concentrations to indicators of tree health, growth, yield and fruit quality. Thus, we should be able to identify and quantify optimal nutrient concentrations in leaves and roots, and to determine if there is a relationship between them. By utilizing both fertigation, soil, and foliar fertilization treatments, we will be able to determine how different fertilization practices impact root nutrition, development and health, and how fertigation influences leaf nutrition and overall tree performance as well as fruit quality and sensory profile. Understanding linkages between root and leaf nutrients will allow for identification of the best fertilization application method and provide more insight on optimal rates of fertilization to improve the performance of HLB-affected trees.