**2. Chemical classification of resistance**

Taking into account the herbicides' mechanisms of action, it is possible to clearly observe a predominance in cases of resistance to the application of the acetolactate synthase (ALS)-inhibiting herbicides in Australia, Canada, and the United States (**Figure 1**), followed by resistance to PSIIinhibiting herbicides in France. The number of resistance cases to PSII-inhibiting herbicides is also high in the other countries, rating this mechanism of action in the second place in number of reported resistance cases in the United States and Canada. In Australia, the number of resistance cases to ACCase and EPSPs herbicides was in the second place, followed by the PSI and PSII herbicides (**Figure 1**).

In comparison to other mechanisms of action, resistance cases to ACCase-inhibiting herbicides were very important in all countries. Moreover, EPSP herbicides were also important in Australia and the United States, but, in general, the number of resistance cases to this mechanism of action was smaller in Canada and France (**Figure 1**). Overall, there were

**Figure 1.** Wordcloud for the occurrence of weeds resistance as a function of mechanism of action in the reference countries. The scale of the font represents the importance of the mechanism compared to the others in the same figure. Source: adapted from Heap [8].

weeds resistant to 12, 8, 4, and 14 herbicidal mechanisms of action, respectively, in Australia, Canada, France, and the United States (**Figure 1**).

**2. Chemical classification of resistance**

PSII herbicides (**Figure 1**).

136 Herbicide Resistance in Weeds and Crops

Source: adapted from Heap [8].

Taking into account the herbicides' mechanisms of action, it is possible to clearly observe a predominance in cases of resistance to the application of the acetolactate synthase (ALS)-inhibiting herbicides in Australia, Canada, and the United States (**Figure 1**), followed by resistance to PSIIinhibiting herbicides in France. The number of resistance cases to PSII-inhibiting herbicides is also high in the other countries, rating this mechanism of action in the second place in number of reported resistance cases in the United States and Canada. In Australia, the number of resistance cases to ACCase and EPSPs herbicides was in the second place, followed by the PSI and

In comparison to other mechanisms of action, resistance cases to ACCase-inhibiting herbicides were very important in all countries. Moreover, EPSP herbicides were also important in Australia and the United States, but, in general, the number of resistance cases to this mechanism of action was smaller in Canada and France (**Figure 1**). Overall, there were

**Figure 1.** Wordcloud for the occurrence of weeds resistance as a function of mechanism of action in the reference countries. The scale of the font represents the importance of the mechanism compared to the others in the same figure. To date (November 2016) in Brazil, there are cases of weeds resistant to five mechanisms of action (**Figure 2**). Furthermore, the majority of these cases is associated with ALS herbicides. In the second place comes the resistance against EPSPs, followed by ACCase, Auxin, and Protox herbicides. Compared to other countries, one may observe that the order of importance of herbicide mechanisms of action in Brazil resembles more closely to the Australia and the United States context (**Figure 1**). The number of resistance cases to ACCase herbicides is similar to Canada; however, resistance to EPSP herbicides is not as important in that country as compared to Brazil. Moreover, the number of resistance cases to each mechanism of action in France was the one that contrasted the most from Brazil (**Figure 1**).

France is characterized by growing large areas of barley, to supply the demand of breweries [9, 10], and oat. Maize is also a common crop in France, where the French production of these crops, potatoes and sugarbeets, helps to meet the demand of these products in Europe [9]. In the cooler regions of France, apples are cultivated, as well as grapes for the production of wine [10]. Other French crops mostly include plums, tomatoes, and peaches [9].

The Brazilian agriculture differs from French crops as it is based mostly on maize, wheat, rice, soybeans, orange (*in natura* and juice), sugarcane (including sugar and ethanol), cotton, cassava, coffee, potatoes. Fruits such as grapes, apples, bananas, mangoes, melons, tobacco, papaya, and

**Figure 2.** Wordcloud for the occurrence of weeds resistance as a function of mechanism of action in Brazil. The scale of the font represents the importance of the mechanism compared to the others in the same figure. Source: adapted from Heap [8].

pulp are also cultivated. Moreover, the paper industry is also important in the country [11]. As the world's sixth largest economy, Brazil ranks third among the world's major agricultural exporters and fourth for food products, being the world's largest producer and exporter of products such as soybean, coffee, sugarcane, orange juice, meat, and tobacco [12].

Thus, there is a great difference between the major crops grown in France and Brazil, which is probably the cause for a distinct herbicide demand and, as consequence, the difference in nature of resistance cases between these two countries.
