Weed control and selectivity in maize (Zea mays L.) with tembotrione mixtures

Field and pot trials were conducted in two sites of northern Greece (Thermi and Lepti) to study selectivity and weed control in maize (Zea mays L.) with herbicide mixtures based on tembotrione. Treatments included tembotrione (plus isoxadifen-ethyl safener) applied alone at 100 g ai/ha and three mixtures of tembotrione with: (i) rimsulfuron at 10 g ai/ha, (ii) nicosulfuron at 40 g ai/ha and (iii) foramsulfuron at 60 g ai/ha (label rates for weed control in maize). Herbicides were applied at the 7-to 8-leaf growth stage of maize in Thermi and at the 6- to 7-leaf growth stage in Lepti. Six weeks after treatment, control of rhizomatous Sorghum halepense with tembotrione alone was 63% in Thermi and 60% in Lepti, with plants showing the typical bleaching symptoms of the HPPD-inhibiting herbicides. Control of rhizomatous S. halepense with the mixtures was improved from 63% to 86% in Thermi and from 60% to 82% in Lepti compared with the single treatment of tembotrione, with plants showing only the symptoms of reddish/purplish color of the ALS-inhibiting herbicides. Control of common broadleaf weeds of maize, such as Xanthium strumarium, Amaranthus retroflexus, Datura stramonium, and Chenopodium album was excellent (92%-100%) either with tembotrione alone or with the mixtures, with plants showing the typical bleaching symptoms of the HPPD-inhibiting herbicides. None of the mixtures affected the ear length and grain yield of maize. All chemical treatments gave higher grain yield than that of the non-treated control and comparable yield to that of the weed-free control. Grass control (Echinochloa crus-galli, E. phyllopogon, and Setaria viridis) with tembotrione alone was above 90% in the pot experiments which was similar to that achieved with the mixtures. Overall, there was an adequate margin of safety in the use of tembotrione in mixture with ALS-inhibiting herbicides for improved weed control in maize, particularly where rhizomatous S. halepense is problematic.