Optimizing herbicide selection for pre-emergence control of itchgrass and cypressvine morningglory in sugarcane.

The aim of this study was to assess the efficacy of herbicides in association to control Rottboellia exaltata and Ipomoea quamoclit during pre-emergence while also to evaluate the potential impact on the sugarcane. The experimental design employed a randomized block with seven treatments and four replications. The treatments were: 1 - no herbicide application; 2 - indaziflam + sulfentrazone; 3 - indaziflam + diclosulam; 4 - indaziflam + tebuthiuron; 5 - flumioxazin + diclosulam, 6 - flumioxazin + pyroxasulfone and 7 - clomazone + sulfentrazone. The evaluated parameters were: percentage of weeds control, green coverage percentage (Canopeo® system), weed biomass (g m-2), itchgrass height, and sugarcane tiller. Several herbicide associations have been proven effective alternatives for managing itchgrass and cypressvine morningglory. The most successful treatments for itchgrass control were indaziflam + tebuthiuron (100%) and indaziflam + diclosulam (97%), whereas for cypressvine morningglory, the betters were indaziflam + sulfentrazone (97%), indaziflam + diclosulam (98%), indaziflam + tebuthiuron (97%), flumioxazin + diclosulam (94%), and clomazone + sulfentrazone (96%). All treatments reduced the weed biomass, with indaziflam + tebuthiuron being the safest option for protecting sugarcane.

Optimizing foliar N-fertilization in sugarcane depends on plant genotype and nitrogen concentration.

Foliar N-fertilization (FNf) has emerged as a promising approach to synchronize plant nitrogen (N) demands and application timing, reducing the N losses to the environment associated with traditional soil-based fertilization methods. However, limited information exists regarding the effectiveness of FNf in sugarcane. This study aimed to optimize FNf in sugarcane by evaluating N-fertilizer recovery by the plant (NRP) and assessing potential toxicity effects. Four sugarcane genotypes were subjected to FNf using 15 N-urea at five nitrogen concentrations. NRP was assessed at five time points for roots, stalk, old leaves, 15 N-urea-fertilized leaves (15 NL), and unexpanded leaves (UEL). Leaf scorching, indicating FNf toxicity, was analyzed using morpho-anatomical and histochemical techniques. The results showed that FNf promoted high NRP, with an average recovery of 62.3%. Surprisingly, the redistribution of 15 N-urea did not follow the nitrogen uptake rate by sugarcane leaves, with an average of 41.3% of the total-NRP. The stalk emerged as the primary sink for 15 N-urea, followed by the UEL. Genotypes differed in the leaf scorching intensity, which increased with higher concentration of 15 N-urea. Genotypes also differed in the 15 N-urea uptake rate, down-regulated by the N content in the 15 NL. These findings emphasize that by carefully choosing the appropriate genotype and nitrogen concentration, FNf can significantly enhance N-fertilizer uptake, resulting in potential environmental and economic benefits.

Selectivity and control of Euphorbia heterophylla in sugarcane by herbicide in post-emergence.

To obtain good control of wild poinsettia (Euphorbia heterophylla) in post-emergence in sugarcane crop, we evaluate the herbicides association on post-emergence of E. heterophylla and the ratoon cane selectivity. The experimental scheme was in randomized blocks with 6 treatments and 4 replications. The treatments were: control; ametryn + mesotrione + sulfentrazone (1,500 + 144 + 800 g i.a ha-1); ametryn + mesotrione + diclosulan (1,500 + 144 + 200 g i.a ha-1); ametryn + mesotrione (2,500 + 144 g i.a ha-1: Highest dose); ametryn + mesotrione (2,000 + 144 g i.a ha-1: Lowest dose) and ametryn + mesotrione + diuron (1,000 + 144 + 1,250 g i.a ha-1). The percentage of control, dry mass, height and percentage of germination of E. heterophylla and injury level, yield and technological quality of sugarcane were evaluated. The best control of E. heterophylla was: ametryn + mesotrione +sulfentrazone; ametryn + mesotrione + diclosulan and ametryn + mesotrione (Lowest dose). As for the ratoon cane selectivity the best yield was achieved with the association ametryn + mesotrione +diclosulan. An appropriate association of herbicide molecules provides successful control of E. heterophylla, especially the association of sulfentrazone or diclosulan together with ametryn and mesotrione.