Tolerance of Caladium Cultivars Florida Cardinal and Florida Fantasy to Sulfonylurea Herbicides

Abstract

There is a need to identify postemergence (POST) herbicides for weed control in field-grown caladium [Caladium bicolor (Aiton) Vent.]. The objective of this research was to evaluate the tolerance of two caladium cultivars Florida Cardinal and Florida Fantasy to POST applications of sulfonylurea (SU) herbicides flazasulfuron, foramsulfuron, imazosulfuron, and mesosulfuron. At 8 weeks after treatment (WAT), ‘Florida Cardinal’ and ‘Florida Fantasy’ treated with the highest rate of imazosulfuron (1680 g a.i./ha) had <10% visual injury, leaf number, height, and tuber weight reduction compared with the nontreated control. Both caladium cultivars exhibited greater susceptibility to flazasulfuron, foramsulfuron, and mesosulfuron as compared with imazosulfuron. The label-recommended rate of flazasulfuron (52 g a.i./ha), foramsulfuron (29 g a.i./ha), and mesosulfuron (15 g a.i./ha) reduced ‘Florida Cardinal’ height 35%, 27%, and 35%, respectively, and reduced ‘Florida Fantasy’ height 43%, 31%, and 21% compared with the nontreated plants, respectively. Caladium tuber weight exhibited a differential cultivar response to the evaluated SU herbicides, except imazosulfuron. The highest rate of flazasulfuron (420 g·ha−1), foramsulfuron (232 g·ha−1), and mesosulfuron (120 g·ha−1) reduced ‘Florida Cardinal’ tuber weight 50%, 65%, and 58% compared with the nontreated control, respectively, whereas these treatments reduced ‘Florida Fantasy’ tuber weight <25%. The mesosulfuron rate required for 20% tuber weight reduction (T20) in ‘Florida Cardinal’ was 2 g·ha−1, but the T20 value was 28 g·ha−1 for ‘Florida Fantasy’. We concluded that the caladium cultivars Florida Cardinal and Florida Fantasy are highly tolerant to the POST applications of imazosulfuron, whereas these caladium cultivars are more susceptible to flazasulfuron, foramsulfuron, and mesosulfuron.