Evaluating the impacts of cover crops in Southeast Florida citrus groves affected by citrus greening: part II—Effects on tree growth

Florida citrus production is severely constrained by citrus greening (huanglongbing, HLB), which reduces fibrous root density and nutrient uptake and has increased reliance on intensive grove management. Renewed grower interest in cover crops and other regenerative practices reflects the need for strategies that improve soil function and nutrient cycling; however, the effects of cover cropping on citrus greening-affected trees remain uncertain. This study evaluated the effects of cover crops on leaf nutrient status, vegetative growth, Candidatus Liberibacter asiaticus (CLas) cycle-threshold (Ct) values, and juice quality in commercial citrus groves in southeastern Florida. A three-season field experiment (January 2022–July 2024) was conducted in four groves near Fort Pierce, FL, USA: one sweet orange, one lemon, and two grapefruit groves. The randomized complete block design included four groves as blocks and two grove-floor treatments: conventional and cover crops. Each treatment included eight 10-tree plots per grove. Warm- and cool-season cover crop mixtures were planted in May and November, respectively, and terminated approximately 6 months after planting. Repeated-measures data were analyzed using linear mixed-effects models. Cover crops produced statistically significant but generally modest changes in leaf N, P, K, and Mg, with responses varying by grove and sampling date. Effects on canopy volume, trunk diameter, and CLas Ct values were also inconsistent. Overall, cover cropping altered leaf nutrient dynamics but did not consistently improve or impair citrus tree growth, citrus greening status, or juice quality.