Effect of low rates of 2,4-D on tomato at different growth stages: injury progression, yield, and fruit residues

Tomato (Solanum lycopersicum) is an economically important vegetable crop in Mississippi. This study involved two controlled greenhouse trials to investigate how sublethal doses of 2,4-D, simulating drift, affect tomatoes at various developmental stages, vegetative, flowering, and fruiting, as well as to evaluate potential residue accumulation in fruit. ‘Sun Gold,’ a cherry tomato variety, was cultivated in containers and exposed a single time to four reduced concentrations of 2,4-D, each combined with 0.25% nonionic surfactant. Plants in the vegetative phase exhibited the highest sensitivity. At the same time, those in flowering and fruiting stages showed progressively less, with injury severity escalating in correlation with dosage over the 1–4 week period post-application. No fruit development was observed in vegetative-stage plants treated at the 1/16× rate, in contrast to flowering and fruiting-stage plants, which yielded fruit. Using high-performance liquid chromatography, fruit samples were tested, revealing no detectable residues at the flowering stage and an average of 0.1844 μg g−1 in some fruiting-stage samples, substantially below the U.S. permissible limit of 10 ppm. Progeny seedlings showed no visible injury. These findings demonstrate that even low-rate 2,4-D exposure can reduce tomato yield when drift occurs early in growth, though residue levels remain very low.