As all herbicides act on pathways or processes crucial to plants, in an inhibitory or stimulatory way, low rates of any herbicide might be used to modulate plant growth, development, or plant composition. Glyphosate is the most used herbicide in the world, and very low rates of this herbicide can stimulate plant growth, an effect called hormesis. Several studies have shown that glyphosate applications at low rates can increase plant growth, induce shikimic acid accumulation, increase photosynthesis and stomatal opening, increase seed production, and shorten the plant life cycle. Low rates of glyphosate applied to leaves have been reported to cause one or more of these effects in an expanding group of species. Under field conditions, pesticide rates are not uniform, causing some target organisms to receive rates that are low enough to cause hormesis. Until the present, low rates of glyphosate have not been recommended as a growth stimulant for crops, because the hormetic dose can vary considerably, depending on many factors. The objective of the present review is to summarize and analyze existing information about the hormetic effects of glyphosate on plants, thus contributing to understanding how glyphosate hormesis takes place and evaluating the potential use of glyphosate to stimulate plant growth. © 2017 Society of Chemical Industry.

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Green cane harvesting is a new agricultural practice that provides many benefits to sugar cane production in Brazil by allowing cane straw to remain on the soil surface. However, this system has complicated the management of weeds, pests and diseases. This review will highlight the impact of green cane harvesting on the management of weeds, insect pests, and pathogens in sugar cane production, and cover novel techniques and practices used to manage pests in this production system. Brazil has a unique agroecosystem that includes tropical and subtropical climates and distinct technical challenges relative to other agricultural regions around the world. Sugarcane stands out as an economically important crop in Brazilian agriculture, both in terms of its planting area and the complexity of the production system (e.g., constant changes in planting, cultural practices, and harvest managements). Brazilian sugarcane production in the 2018/2019 season was 620.44 million tons produced over more than 8.5 million hectares distributed mainly in the states of São Paulo, Goiás, and Minas Gerais. Currently, 38% of this production is intended to produce sugar and 62% to ethanol, generating 29.04 million tons of sugar and 33.14 billion liters of ethanol, making Brazil the largest sugar and ethanol producing country in the world. The sugarcane agroindustry continues to expand in Brazil, showing a great capacity to aggregate value to byproducts of ethanol and sugar, such as vinasse (fertilizer), filter cake (fertilizer and soil conditioner), bagasse (raw-material for industries; animal feed; and electrical energy generation), and plant straws (electrical energy generation). The adoption of mechanized harvests without burning has allowed accumulation of sugarcane straw residues over the cropping area (green cane harvesting). Approximately 84% of the sugarcane production area in Brazil follows green cane harvesting practices. This harvesting system has made the management of weeds, pests and diseases even more complex in sugarcane fields than before. Green cane harvesting has made pest and weed management (mainly) more complex. The presence of residues on the soil directly affects the action of pre-emergent herbicides that are most commonly used in sugarcane and increases the incidence of some important pests such as S. levis and M. fimbriolata. Integration of management programs for weeds, pests, and diseases generates economic benefits and control efficacy (broad spectrum action), maximizing their individual efficacy level, reducing the dependence on only one of them and the risk of selection of resistant pest populations. Monitoring, planning, and evaluation of the history of the sugarcane fields are essentials and assist in decision making regarding the method and time of control to be used. The efficiency of this system assists in the maintenance of high yields, health, and longevity for sugarcane fields.

-This study aimed to identify the response of wandering jew (Commelina benghalensis L.) plants to different doses of glufosinate ammonium and the sensitivity of plants populations to the herbicide. Two studies were conducted, both in a greenhouse, and were repeated at different times. In the first study, two experiments were conducted to examine the dose-response curve using seven different doses of the glufosinate ammonium herbicide (0, 50, 100, 200, 400, 800, and 1600 g a.i. ha -1 ) with four replicates each. In the second study, which examined the range in sensitivity of wandering jew plants to glufosinate ammonium, 26 plants were sprayed with a dose of 200 g a.i. ha -1 herbicide. Visual assessments of percent injury and measurements of leaf tissue ammonium content were conducted. The use of untreated wandering jew control plants allowed for the correlation of glufosinate ammonium treatment with the ammonium concentrations in treated plant tissues; the ammonium concentration increased as a function of herbicide application, albeit not linearly with the dose. Ammonium content varied among individuals of the wandering jew plant population.Keywords: Ammonia. Commelina benghalensis L.. Glutamine synthetase. Weed. VARIAÇÃO DA SENSIBILIDADE DE PLANTAS DE TRAPOERABA AO AMÔNIO GLUFOSINATERESUMO -Esse trabalho teve como objetivo identificar a resposta de plantas de trapoeraba (Commelina benghalensis L.) a diferentes doses de amônio glufosinate e a sensibilidade de uma população de plantas ao herbicida. Foram realizados dois estudos, ambos implantados em casa de vegetação e repetidos em diferentes momentos. No primeiro, referente à curva de dose-resposta, realizou-se dois experimentos, tendo como tratamentos sete doses do herbicida amônio glufosinate (0; 50; 100; 200; 400; 800; 1600 g i.a. ha -1 ), com quatro repetições cada. Já no segundo, referente à variação da sensibilidade da trapoeraba ao amônio glufosinate, 26 plantas foram pulverizadas com a dose de 200 g i.a. ha -1 do herbicida. Realizou-se avaliações visuais de injúria e análises do teor de amônia nos tecidos foliares. O controle de plantas de trapoeraba pelo amônio glufosinate pode ser correlacionado ao teor de amônia nos tecidos vegetais, que aumenta em função da aplicação do herbicida, porém não de forma linear em função da dose. Houve variabilidade quanto ao teor de amônia entre indivíduos de uma população de trapoeraba.Palavras-chave: Amônia. Commelina benghalensis L.. Glutamina sintetase. Planta daninha.

The objective of this study was to evaluate the response of hairy beggarticks plants to different doses of glufosinate ammonium and the range in sensitivities of the plants and their progenies to the herbicide. Three studies were conducted, all in a greenhouse and repeated at different times. In the first study, two experiments were conducted to examine the dose–response curve, and the treatments were seven different doses of the herbicide glufosinate ammonium (0, 50, 100, 200, 400, 800, and 1,600 g ai ha−1), with four replications each. In the second study, which examined the range in sensitivity of hairy beggarticks to glufosinate ammonium, 44 plants were sprayed with a dose of 200 g ai ha−1of the herbicide. Finally, in the third study, the range in sensitivity of the progeny of hairy beggarticks to glufosinate ammonium was investigated; in this experiment, the progenies of seven of the previous plants were sprayed with 200 g ai ha−1of herbicide. The ammonium contents in the tissues were measured and percent injury wase visually assessed. Ammoniun content in hairy beggarticks leaves was increased more than seven times by glufosinate application and the maximum ammonium content was observed for the highest dose of the herbicide. Variability existed in the ammonium content among the individuals of the population of hairy beggarticks; however, the behavior was not replicated in the same way in the progenies. The survival of the plants after application of the herbicide allows the production of progenies with wide variability in their sensitivity to the product, independent of the behavior for the progenitor plants.