Sensitivity of Chenopodium album and Abutilon theophrasti to mesotrione depending on the growth stage

Growth stage of weeds can significantly affect the level of control at the moment of herbicide application. Maturation of plants usually lead to decreased sensitivity of plants. The aim of this research was to determine whether growth stage of weed species can affect the sensitivity of Chenopodium album and Abutilon theophrasti to mesotrione at the moment of application. Seeds of these species were sown in 5 days interval to ensure that at the moment of herbicide application Ch. album would be in stages of 2, 4, 6, 8 and 10 leaves and A. theophrasti in stages of 1, 2, 3, 4 and 5 leaves. When plants reached this stages herbicide Skaut (mesotrione 480 g/l) was applied in recommended dose rate 0.25 l/ha in tank-mix with adjuvant Alteox wet 40 (mineral oil (500 g/l) and polyoxyethylene alcohol (500 g/l)) in the dose rate 1 l/ha. The results showed that growth stage at the moment of application of mesotrione can significantly affects the sensitivity of both species to herbicide. The application of herbicides in the early growth stages (A. theophrasti - 1 leaf, Ch. Album - 2 and 4 leaves) resulted in total control of plants. With further maturation, sensitivity has decreased, in terms that the lowest effect was noted with A. theophrasti in growth stage of 5 leaves and Ch. album in growth stage of 10 leaves.