The impact of a tree virus on production value

Purpose – This paper seeks to investigate the impact of citrus tristeza virus (CTV) on the commercial value of fruit produced by navel orange trees. Design/methodology/approach – Data are counts of fruit of various sizes and quality harvested from a tree in a year. The counted fruit are converted to a dollar value using a standardized pricing matrix and then normalized as a ratio of the tree value compared to trees in the same orchard and year that were free of virus. Statistical tests determine if trees at various stages of infection have different production values than virus‐free trees. Findings – On average, trees infected with CTV have higher fruit production values than trees that did not contract the virus, after compensating for climate and location differences, even though the presence or absence of CTV explains only about 1 percent of the variation in production value. Research limitations/implications – Data are from commercially maintained orchards rather than a carefully controlled experiment in an isolated greenhouse environment. Practical implications – Orange growers in the region should be reluctant to remove trees that have mild strains of CTV. The effects of a tree virus on production value should be a consideration in how to respond to the virus. Originality/value – Development of a standardized pricing matrix to control for pricing fluctuations from year to year is a relatively novel concept. The applied concepts of tree status cohorts and relative crop values are original and provide valuable tools for combining data from different orchards and climate conditions.