Effectiveness of Harvesters at Identifying and Removing Citrus Fruit with Canker Symptoms in the Field

Abstract

During the 2008–10 citrus seasons, experiments were conducted to evaluate the ability of harvesters to identify and remove grapefruit with canker symptoms. The harvesting methods evaluated included: 1) current harvest practices without field grading, 2) harvester grading after picking, and 3) harvester grading before picking. The fruit used in this research were collected from commercial ‘Ray Ruby’ grapefruit groves. Some experiments were harvested by trained laboratory personnel, whereas others were harvested by professional harvesters. Compared to current practices, removing fruit with canker lesions during harvest was not effective. While laboratory personnel tended to be more accurate at distinguishing symptomatic and asymptomatic fruit than professional harvesters, they took more  than twice the time to harvest the same amount of fruit. On the other hand, between 29% to 68% of the fruit that professional harvesters thought had canker lesions were actually asymptomatic, while between 8% and 38% of the fruit that they thought were asymptomatic, actually were not. This substantial amount of fruit incorrectly identified as
symptomatic represents lost revenue, whereas fruit with canker lesions that were not detected must still be removed at the packinghouse. The extra effort of identifying fruit with canker lesions during harvest would also increase harvesting costs by perhaps 33% to 67% and could increase the time required to harvest the fruit by up to 65%. Results from this research suggest that removing fruit with citrus canker lesions during harvest would not be effective or economic under current Florida conditions.