Possible mechanisms for surfactant‐induced foliar uptake of agrochemicals

Abstract

In the past many mechanisms of action have been proposed to explain the surfactant‐induced uptake of agrochemicals applied to foliage. These are reviewed briefly and discussed in relation to potential sites of uptake activation, particularly in the light of recent radiochemical work on the foliar uptake behaviour of surfactants on intact plants in the presence or absence of model penetrants and pesticides. The body of evidence available is examined in relation to the many outstanding problems that still exist in understanding the role and use of surfactants as uptake activators in agrochemical formulations.

Suscetibilidade de duas Gramas-boiadeiras a diferentes formulações de glyphosate

“…A variação entre os valores de C 50 , GR 50 e EST 50 podem estar relacionada às particularidades de cada formulação do herbicida, como diferenças na velocidade de absorção, translocação e ação (MOLIN & HIRASE, 2005). Os adjuvantes presentes nas formulações de glyphosate podem atuar no aumento da permeabilidade da cutícula e da membrana celular, além de melhorar a deposição e retenção do herbicida nas folhas (STOCK & HOLLOWAY, 1993). A formulação do sal isopropilamina (Roundup Transorb ® ), devido à sua composição, apresenta maior velocidade de absorção e translocação em relação às demais formulações encontradas no mercado (SANTOS et al, 2005).…”

Acute toxicity and histopathological alterations of Roundup® herbicide on "cachama blanca" (Piaractus brachypomus)

“…Brain alterations indicate degenerative neuronal processes (Fig.11) that have not been described following exposures to herbicides. These components can gain access to the central nervous system through the olfactory epithelium and then to the olfactory bulb in the telencephalon, this could agree with the focalization of degenerative neuronal processes to the olfactory bulb, and/ or through the blood/brain barrier where the surfactant components because of their amphiphylic character and incorporation into biological membranes could facilitate access of GP and its own passage (Stock & Holloway 1993). Predisposition of the olfactory bulb to degenerative foci could be generated by its communication with the olfactory epithelium and/or by the presence of proliferation centers and neural regeneration (Lema et al 2005) where Roundup ® components might induce alterations in the control points of the cellular cycle or in transcription processes that occur during neurogenesis (Marc et al 2002(Marc et al , 2003(Marc et al , 2004a(Marc et al ,b, 2005.…”

Seletividade de acaricidas utilizados em cafeeiro para larvas de crisopídeos

“…Entretanto, a alta mortalidade de insetos observada no tratamento à base de fenpropatrina pode ter ocorrido em função do seu peso molecular (349,0), visto que piretróides com pesos moleculares menores possuem maior capacidade de penetração na cutícula do inseto (Stock & Holloway, 1993;Berg et al, 2003), podendo potencializar o seu efeito.…”