Residual Activity of [imazapic+imazapyr] Applied to Imidazolinones Resistant Soybean on Cotton in Succession

Abstract

In the current scenario of resistance of weeds to glyphosate in grain and fiber production systems, imidazolinone-resistant soybean is shown as an option in the rotation of biotechnology events and herbicide action mechanisms through the application of [imazapic+imazapyr]. However, due to its persistence in the soil, the herbicide may harm the subsequent crop. The objective of this work was to evaluate the residual activity of the herbicide [imazapic+imazapyr] applied in pre-emergence in soybean cultivation on cotton in succession. The experimental design was a randomized block design with five replicates, using seven concentrations (0; 6.25; 12.5; 25; 50; 100 and 200%) of the recommended dosage of the herbicide [imazapic+imazapyr] ([78,75+26,25] g ha-1). The cotton was sown 112 days after application of the herbicide with accumulated rainfall of 637 mm during the soybean cycle, totalizing 1,043 mm until the cotton harvest. There was no significant difference for the analyzed variables. It is concluded that the BRS 8482cv soybean cultivar is resistant to double of the recommended dosage ([157.5+52.5] g ha-1) of [imazapic+imazapyr], and its residual soil activity does not affect cotton cv. TMG 42 WS, in the 112 day interval between pre-emergence herbicide application in soybean cultivation and sowing of cotton.

Comparative Analyses of Glyphosate Alternative Weed Management Strategies on Plant Coverage, Soil and Soil Biota

“…Like glyphosate and glufosinate, imazapyr activity is reduced in soils by microbial activity [92]. The data presented here shows soil bacterial and fungal relative abundance was minimally (if at all) impacted by imazapyr treatment, which is consistent with previous investigations [92][93][94].…”

Development of lawns in response to applications of imazapic alone or combined with imazapyr

“…It is assumed that the significant reductions in the height and number of inflorescences of Tifton 419 grass for a long period (49 days) (Table 6) can be explained by the high values of the half-life of the herbicides in the soil, considering that the half-life of imazapic alone is estimated to last 40 to 120 days, while the imazapic and imazapyr mixture may have a long half-life, ranging from 30 to 200 days after application (DAA) (Bajrai et al, 2017;Matte et al, 2018;Yavari et al, 2019).…”

Use of the imazapic herbicide applied alone or tank mix with imazapyr as growth regulator of lawns

“…The most persistent herbicides have the advantage of providing long-lasting efficiency but may have residual activity and a direct influence on the growth parameters of sensitive plants, depending basically on the soil, environmental conditions, and physicochemical properties of the herbicide (Matte et al 2018).…”

“…The imazapic herbicide, for instance, is often used to control some grass species and broadleaf weed plants in pre-and post-emergence applications (Rinella et al 2013;Bajrai et al 2017). The imazapic + imazapyr formulated mixture is also recommended for the control of weed plants such as sedge (Cyperus rotundus L.), little bell (Ipomoea grandifolia (Dammer) O'Donell) and wild poinsettia (Euphorbia heterophylla L.) (Matte et al 2018). However, Maciel et al (2013) report that besides the herbicide action, imazapic can also be selective and viable for use as regulator of grass plant growth and development and can reduce the number of lawns cuttings.…”