Together and mixed

In the mid-1980s, all recommendations on tank mixing were removed from the instructions for use following guidance from the Ministry of Agriculture, Livestock and Supply (Mapa). After many discussions and ten years later, they were regulated by Mapa Ordinance No. 67, which allowed companies to include tank mixture recommendations in their records. However, this ordinance ended up being revoked by Normative Instruction 46/2002 and until then a solution is awaited from the competent government bodies.

Throughout this period, the question we heard most was: is mixing prohibited or not? A legal study commissioned by the Brazilian Association of Generic Defensives (Aenda) in 2011 concluded that tank mixing is not prohibited and can be practiced by the farmer, under his responsibility. However, it cannot be prescribed by a legally qualified professional using an agronomic prescription, as any agrochemical can only be recommended by observing the usage information approved on the label and leaflet (Decree 4.074/02). Therefore, the understanding, from a legal point of view, is that tank mixing is not prohibited.

In practice, it is common for insect pests, weeds and diseases to occur simultaneously in the same crop. Furthermore, many insecticides, herbicides and fungicides have a specific spectrum of action, that is, they do not control all target species. This characteristic contributes to some producers opting for tank mixing in order to reduce costs and optimize phytosanitary treatments.

 With the lack of regulation, information about tank mixtures, from safe sources, became scarce, creating insecurity and risks for farmers and technicians. The fear of fines from public authorities discouraged the generation and transfer of information, and created a contrast with what happens in practice, since tank mixing on agricultural properties in Brazil is common.

On the other hand, products formulated as a mixture, that is, previously mixed by the industry, can be registered in Brazil, but they do not meet the diversities that commonly occur in the field, due to a lack of spectrum of action or dose of the mixed active ingredients. Furthermore, the number of registered products also does not meet the needs of the field. On the other hand, tank mixing allows a case-by-case solution, individualized for each type of problem, and with the advantage of being carried out based on a professional's diagnosis.   

To understand the reality of the use of agrochemical tank mixtures on agricultural properties in Brazil, a study was carried out (Gazziero, 2015), in which private technical assistance agents (consultants), technical assistance linked to the government, technical assistance linked to cooperatives and rural producers. The results show that 97% of pesticide applications are made with tank mixtures (Figure 1), and that 95% of mixtures involve the use of two to five associated products in a single tank. In 5% of cases, there is a mixture of six or more products applied simultaneously (Figure 2). It was also found that 69% of the time the products are placed directly in the spray tank, and in 31% they are pre-mixed before being placed in the sprayer. Premixing is recommended to check for unwanted reactions.

In the view of those interviewed, there are numerous advantages that can be cited with the use of agrochemicals in mixtures, such as: saving time, labor, water, diesel oil, agility in operations, ease of crop management, reduction of soil compaction, increasing the spectrum of action of the products, resistance management and application at the appropriate time. Regarding disadvantages, the lack of regulation, concern about risks to health and the environment, the possibility of phytotoxicity, chemical incompatibility, reduced efficiency (antagonism) and greater wear and tear on equipment were highlighted.

Among those interviewed, only a third were unaware of any problems with the mixtures, while the majority confirmed that there was a possibility of some type of problem occurring, such as difficulty in dissolving the mixed products, phytotoxicity, excessive foam formation, clogging of nozzles and decantation of products in the tank. In spraying, this cannot occur under any circumstances. Another important observation to be highlighted in the work carried out by Gazziero (2015) was the consensus among interviewees that information about mixtures is not sufficient. This encourages reflection: if the practice of tank mixing is so common and necessary for agriculture, why not regulate it?

 The regulation of tank mixing of agrochemicals is a subject of interest to everyone who works in the area of ​​plant health, and especially to farmers and professionals who provide technical assistance. Mixing products with different mechanisms of action is a worldwide recommended practice to prevent or manage problems with insect pests, diseases and resistant weeds. Pest resistance to herbicides, fungicides and insecticides is currently a global threat, which directly affects agriculture in Brazil.

Several public and private institutions that believe in the need for a solution to the case of tank mixes have been working with the federal government to prepare a Joint Normative Instruction by the Ministries of Agriculture, Health and Environment, so that regulation of mixtures becomes a reality. The discussions take into account international legislation used in developed countries, a rigorous risk analysis and the Brazilian reality. The fact is that Brazil needs to come up with a solution. Since the mid-80s, countless motions requesting regulation have been made to the government, however, without success. However, a solution has never been as close as it is today, as the competent bodies understand that this problem must be definitively resolved. There is an expectation that a decision will be taken in 2017, as farmers cannot continue working with the lack of necessary information, just as legally qualified professionals should not be prevented from working on this matter. Regulation by government bodies, as occurs in other countries, will allow information to circulate freely, reaching users and resulting in economic, agronomic, environmental and worker health benefits.  

 

 *The article was published in Cultivar Grandes Culturas, issue 220, September 2017.