Atrazine nanoencapsulation improves pre‐emergence herbicidal activity against Bidens pilosa without enhancing long‐term residual effect on Glycine max

Abstract

BACKGROUND Poly(ϵ‐caprolactone) nanocapsules (NC + ATZ) are an efficient carrier system for atrazine and were developed as an alternative to reduce the harmful environmental effects of this herbicide. Here, we analyzed the pre‐emergence herbicidal activity of NC + ATZ against Bidens pilosa and evaluated its residual effect on soybean plants after different periods of soil treatment with the formulations. RESULTS In contrast to non‐nanoatrazine, NC + ATZ treatment led to very high mortality rates of B. pilosa seedlings even after a tenfold dilution, which suggests that atrazine nanoencapsulation improved its pre‐emergence herbicidal activity. In a short‐term assay (17 days), soil treatment with all atrazine‐containing formulations resulted in intense toxicity to soybean plants. NC + ATZ at 200 g ha−1 had the same inhibitory effects on the physiological and growth parameters of soybean plants compared with non‐nanoatrazine at 2000 g ha−1, which suggests that atrazine nanoencapsulation increased the short‐term residual effect of the herbicide. In a long‐term assay (60 days), a gradual recovery of soybean plants from atrazine phytotoxicity was observed. When comparing the effects of nano‐ and non‐nanoatrazine at the same concentrations, the growth and physiological parameters of soybean plants were mainly affected to the same extent. This indicates that encapsulation of atrazine into poly(ϵ‐caprolactone) nanocapsules did not enhance the long‐term residual effect of the herbicide on soybean. CONCLUSION NC + ATZ could be applied for efficient weed control without additional phytotoxicity to susceptible crops compared with non‐nanoatrazine, provided that a safe interval is respected from atrazine application to sowing. © 2019 Society of Chemical Industry

Biological effects of the free and embedded metribuzin and tribenuron-methyl herbicides on various cultivated weed species

“…[30] Maximum quantum yield decreased when the B. pilosa weed and soybean (Glycine max) were treated with a commercial formulation of atrazine and the herbicide encapsulated in nanocapsules of poly(e-caprolactone). [31] An ETR decrease was detected after atrazine treatment of maize, weeds, and Calophyllum brasiliense. [32] Application of nanocapsules with atrazine decreased Y(II) and ETR in the Amaranthus viridis and Bidens pilosa weeds.…”

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“…These NPs inhibit the physiological processes and growth phases in several weed species. For example, Ch-NPs retard germination and growth phases in Bidens pilosa [ 130 , 131 ] NPs atrazine disrupts PSII activity in Amaranthus viridus [ 132 ], Fe 3 O 4 NPs (Iron oxide NPs) + purified diatomite + glyphosate decrease pH level in Cynodon dactylon [ 133 ], Zero valent Fe NPs (Iron NPs) retard germination in Lolium perenne [ 32 ]. The efficacy of metribuzan, (a commercial herbicide) was enhanced via using NPs to maintain the growth of the weed population including Melilotus album, T. aestivum, Agrostis stolonifera, and Setaria macrocheata [ 19 ] .…”

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“…Nanopesticides have been very successfully tested for control of pine wilt nematode, with nanoencapsulated avermectin shown to have superior toxicity to the nematode's gastrointestinal system, greater sustained-release performance and improved photolytic stability in comparison to a traditional delivery of avermectin (Su et al, 2020). Nanoencapsulating atrazine has also been found to reduce the harmful environmental effects of this herbicide, without negatively affecting the mortality rate of Bidens pilosa seedlings (Preisler et al, 2020). Nanoencapsulated atrazine in the latter study had inhibitory effects at 200 g/ha that were equivalent to those of nonencapsulated herbicide at 2 000 g/ha, representing a ten-fold reduction in the herbicide concentration.…”