Effect of windbreaks on wind speed and canker incidence on grapefruit

Abstract

For fresh grapefruit, the goal is to maximize pack-out by minimizing canker lesions on fruit. The objective of these trials was to determine the relationship between wind speed and incidence and severity of citrus canker on 5 to 7 yr-old Ruby Red grapefruit trees located in two trial blocks (∼4.5 ha) surrounded on all sides by a 6 to 10 m tall Corymbia torelliana windbreak. The experiment was conducted from 2013 to 2015. A series of weather stations were deployed in east-west and north-south directions across the orchards to measure the effect of proximity of citrus trees to the windbreak on wind speed expressed as the number of wind gusts ≥5 m s-1, and to determine the relationship with incidence of fruit lesions on grapefruit. The number of wind gusts ≥5 m s-1 increased with distance from the windbreak. The highest fruit canker incidence occurred in approximately the central zone of the block and the lowest incidence was found nearest windbreaks. Number of wind gusts and canker were linearly related, i.e., the greater the number of gusts, the higher the fruit disease. As the number of wind gusts increased with distance from the windbreak, incidence of unsightly wind scar also increased. These results confirm that windbreaks are a highly effective method for protection of fruit from infection by Xanthomonas citri subsp. citri, as well as physical damage from wind buffeting.