Effect of Low Rate of Dicamba on Tomato (Solanum lycopersicum) at Different Growth Stages

Abstract

Tomatoes are highly sensitive to herbicides, and concerns have been raised regarding off-target movement of dicamba and 2,4-D with the advent of new technologies in crops like soybean and cotton. Greenhouse studies were conducted over two years to assess the effect of low rates of dicamba on tomatoes at different growth stages and investigate fruit contamination. Treatments included untreated controls and dicamba applied at 1/16X, 1/32X, 1/64X, and 1/128X rates with non-ionic surfactant (NIS). Tomato plants at three growth stages (vegetative, flowering, and fruiting) were evaluated for dicamba sensitivity. Vegetative stage plants showed the highest sensitivity, while no significant differences in injury were observed between flowering and fruiting stages. Only the untreated controls produced fruit at the vegetative stage. Plants at flowering and fruiting stages successfully produced fruits. Harvested tomato fruits from each dicamba rate and the untreated control were planted, and progeny (F1) seedlings were evaluated for dicamba symptomology. No visual dicamba symptoms were observed in the tomato progeny, indicating the absence of dicamba contamination. High-performance liquid chromatography analysis confirmed no detectable levels of dicamba in the fruit samples. These findings indicate that low rates of dicamba, even at simulated drift levels, do not significantly affect tomatoes or result in fruit contamination. The results contribute to understanding the risks associated with herbicide drift and its impact on sensitive crops like tomatoes.