Influence of the sowing depth and amount of sugarcane straw on the emergence of Chloris polydactyla and Eleusine indica and their control by herbicides applied pre-emergence

Abstract

Influence of the sowing depth and amount of sugarcane straw on the emergence of Chloris polydactyla and Eleusine indica and their control by herbicides applied pre-emergence Influência da profundidade de semeadura e da quantidade de palha de cana-de-açúcar na emergência de Chloris polydactyla e Eleusine indica e controle por herbicidas aplicados em pré-emergência AbstractThe objective of this study was to evaluate the effect of the sowing depth and amount of sugarcane straw on the soil on the emergence of Chloris polydactyla ('capim-branco') and Eleusine indica (Indian goosegrass) and to determine the efficacy of herbicides applied pre-emergence in the control of these species under different straw amount and rainfall regime conditions. The experiments were conducted in a completely randomized design with four replications. In the first experiment, the effects of six sowing depths (0.5, 1, 2, 4, 8, and 10 cm) and six sugarcane straw amounts (0, 1, 2, 4, 8 and 10 t ha -1 ) were assessed on the emergence of Indian goosegrass and 'capim-branco' in a 6 x 6 factorial arrangement. In the second experiment, the efficacy in the control of these species was evaluated for one control without herbicide and five treatments (indaziflam, metribuzin, tebuthiuron, indaziflam + metribuzin, and indaziflam + tebuthiuron) applied pre-emergence over four straw amounts (0, 1, 2, and 4 t ha -1 ) in a 6 x 4 factorial arrangement. This experiment was evaluated under two rainfall regimes in separate experiments (simulation of 20 mm of rainfall 1 or 10 days after herbicide application). The 'capim-branco' showed a marked reduction in emergence beginning at 2 t ha -1 of straw and a 2 cm sowing depth. For the Indian goosegrass, the decline in emergence mainly occurred beginning at 4 t ha -1 of straw and a 4 cm sowing depth. Only some of the Indian goosegrass plants emerged at the greater sowing depths (8 and 10 cm) and straw amounts (8 and 10 t ha -1 ), whereas no emergence of the 'capimbranco' was observed under these conditions. The treatments with sowing at a 1 cm depth and with 0, 1, 2, and 4 t ha -1 of straw provided the highest emergence percentage for the species. Application of the herbicide indaziflam alone was the only ineffective treatment for the control of the weeds regardless of the amount of straw and the water regime used. We concluded that the increase in the sowing depth and the amount of straw significantly reduced the emergence of the species and that the presence of straw and the dry period interfered with the herbicide efficacy. Key words: Indian goosegrass. 'Capim-branco'. Sugarcane. Straw. ResumoObjetivou-se com esse trabalho avaliar o efeito da profundidade de semeadura e da quantidade de palha de cana-de-açúcar sobre o solo na emergência de Chloris polydactyla (capim-branco) e Eleusine indica (capim pé-de-galinha), assim como determinar a eficácia de herbicidas aplicados em pré-emergência no controle dessas espécies, sob diferentes quantidades de palha e regimes de precipitação pluvial. Os experimentos foram real...

Cover Crop Straw Interferes in the Retention and Availability of Diclosulam and Diuron in the Environment

“…The water holding capacity of the straw can also influence the retention of the herbicide, which, through the capillarity existing in the process of hydration of the pores with water and herbicide, causes the physical trapping of the product in the straw pores to occur (Table S6) [75]. The results of our research corroborate the results obtained by other researchers, where insufficient amounts of rainfall and the presence of straw reduces the transposition process and can compromise the effectiveness of the product [18,[76][77][78]. On the other hand, the reduction in the availability of these compounds in cropping systems containing straw, especially of black oats, can contribute to the reduction in environmental risks and dissipation of herbicides.…”

Indaziflam: Leaching and control of Urochloa plantaginea in applications on coffee litter with different rainfall simulations

“…This indicates that the application of indaziflam on coffee litter followed by intervals without rainfall, may result in less effectiveness of the product in controlling weeds (Da Silva et al, 2019). Malardo et al (2017) observed that the efficacy of indaziflam (0.07 kg a.i. ha -1 ) in controlling Eleusine indica and Chloris polydactyla was lower when the 20 mm rainfall occurred 10 days after application, concluding that the presence of straw and the dry period interferes with the effectiveness of the herbicide.…”

“…In this context, indaziflam is a pre-emergence herbicide option in coffee crop, which presents the mechanism of action to inhibit cellulose biosynthesis (chemical class "alkylazine") (Tompkins, 2010). This herbicide has a broad spectrum of action, controlling both monocots and eudicots (Brosnan et al, 2011;Brosnan et al, 2012), and its greatest effectiveness is related to the control of monocot weeds (Amim et al, 2014;Malardo et al, 2017;Da Silva et al, 2020). As for the physical and chemical characteristics, it has low water solubility (2,010 mg L -1 ) and high Kow (2.0 at pH = 2.0; 2.8 at pH = 4 and pH = 9) Almeida, 2018).…”