Effects of Glyphosate Application on Preharvest Fruit Drop and Yield in ‘Valencia’ Citrus

Abstract

The use of glyphosate as a post-emergent weed management tool is crucial in Florida citrus production. However, extensive and nonjudicious application of glyphosate has drawn increasing concerns about its inadvertent effects on citrus, mainly linked to its possible impacts on preharvest fruit drop. Our study investigated the effect of applying glyphosate in the tree rows near the fruit harvesting window on fruit drop and yield in ‘Valencia’ sweet orange. Field trials were conducted at Southwest Florida Research and Education Center, Immokalee, FL. The experiments had a randomized complete block design with four replications. Three different doses of glyphosate within the labeled range of rates in citrus (i.e., low, medium, and high at 0.84, 2.10, and 4.20 kg acid equivalents of glyphosate per hectare, respectively) along with a water control treatment were sprayed in ‘Valencia’ citrus tree rows close to the harvesting period and assessed for their effects on preharvest fruit drop and yield. Our findings show that glyphosate application near the harvesting window may influence the fruit detachment force (FDF) in Valencia citrus; however, no significant effect on increasing fruit drop or reducing yield was observed during this 2-year study.

Keywords

• abscission
• fruit detachment force
• herbicide
• huanglongbing (hlb)
• sweet orange
• weed control