Post-Emergence Herbicidal Activity of Nanoatrazine Against Susceptible Weeds

Abstract

Poly(ε-caprolactone) (PCL) nanocapsules have been previously developed as a carrier system for atrazine. However, the efficacy of this nanoformulation against weeds commonly found in crop cultures has not been tested yet. Here, we evaluated the post-emergence herbicidal activity of PCL nanocapsules containing atrazine against Amaranthus viridis (slender amaranth) and Bidens pilosa (hairy beggarticks), in comparison with a commercial formulation of atrazine. For both species, treatment with atrazine-loaded nanocapsules (at 2,000 g ha −1) led to a greater decrease in the photosystem II activity (above 50% inhibition relative to the control) than the commercial atrazine formulation at the same concentration (around 40% inhibition). The growth of A. viridis plants was equally reduced by nanoatrazine and commercial formulation (above 64% for root and 75% for shoot). In the case of B. pilosa, atrazine-loaded nanocapsules decreased more effectively the root and shoot growth than the commercial formulation, leading to a loss of plant biomass. Moreover, for both species, the use of 10-fold diluted atrazine-loaded PCL nanocapsules (200 g ha −1) resulted in the same inhibitory effect in root and shoot growth as the commercial formulation at the standard atrazine dose. These results suggest that the utilization of atrazine-containing PCL nanocapsules potentiated the post-emergence control of A. viridis and B. pilosa by the herbicide. Thus, this nanoformulation emerges as an efficient alternative for weed control.

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

“…In contrast, the tenfold dilution of non‐nanoatrazine compromised its pre‐emergence herbicidal activity. Similar results have been reported for the same nanoatrazine and non‐nanoformulation in the post‐emergence control of B. juncea , B. pilosa and A. viridis , suggesting that atrazine nanoencapsulation potentiates both its pre‐ and post‐emergence herbicidal activity . Thus, nanoencapsulation would allow a reduction in applied atrazine levels, maintaining satisfactory weed control concomitant with reduced environmental contamination.…”

“…For example, the high sand percentage and low organic matter content of the soil used in the present study are probably related to the intense residual effect detected here, as the low atrazine sorption to soil organic and inorganic particles increases the herbicide availability to the plants . Although the current results, together with previous studies of our group, have shown satisfactory control of different plant species by nanoatrazine, field experiments with mixed weed populations are essential to verify the efficacy of this nanoformulation under realistic conditions . Further studies are also needed to elucidate the possible toxic effects of these nanocapsules to non‐target organisms, such as the soil microbiota.…”

“…Moreover, this nanoformulation showed reduced toxicity toward some non‐target organisms, such as the human cells, the algae Pseudokirchneriella subcapitata and the fish Prochilodus lineatus , compared with non‐nanoherbicide . The nanoencapsulation improved the post‐emergence herbicidal activity of atrazine against target species ( Brassica juncea , Bidens pilosa and Amaranthus viridis ), whereas the growth of maize plants was not affected . Therefore, in comparison with the non‐nanoherbicide, a tenfold reduction in atrazine dosage was enabled when atrazine‐containing PCL nanocapsules were applied for the post‐emergence control of target plants .…”

“…Despite evidence for the efficient pre‐emergence control of Brassica sp. by nanoatrazine, a decreased atrazine dosage for pre‐emergence control of weeds allowed by atrazine nanoencapsulation has not been investigated, as described for post‐emergence assays …”

“…14,18,19 The nanoencapsulation improved the post-emergence herbicidal activity of atrazine against target species (Brassica juncea, Bidens pilosa and Amaranthus viridis), whereas the growth of maize plants was not affected. [20][21][22] Therefore, in comparison with the non-nanoherbicide, a tenfold reduction in atrazine dosage was enabled when atrazine-containing PCL nanocapsules were applied for the post-emergence control of target plants. 20,22 This would result in an enormous decrease in atrazine input to the environment without compromising weed control.…”