Brazil approves Arysta's herbicide Select 240 EC

Brazil's Ministry of Agriculture, Livestock, and Supply(MAPA) has released the extension of the use of the herbicide SELECT 240 EC to control weeds on the pre-planting of corn and wheat crops. The product, developed by Arysta LifeScience, is used on corn against ryegrass and on wheat against weeds such as ryegrass and oats.

SELECT 240 EC is also commonly known as Cletodim. It contains a concentation of 240g/L and a emulsifiable concentrated formulation of the chemical group cyclohexanedione oxime. The action mechanism is systemic, "post-emergent" and classified in the ministry under the register 479097.

The product is systemic, highly selective, and already was used over crops such as soybeans, kidney beans, tomatoes, potatoes, onion, garlic, carrots, coffee, tobacco, manioc, and watermelon. It is effective against a wide range of annual and perennial grasses, with little or no activity on broadleaf weeds and sedges.

The ryegrass, besides being used as pasture, has became the main on the crops with winter cereals in several Brazilian states. "Of the one million hectares grown in the state of winter cereals, it is estimated that 80% show an incidence of ryegrass, which is the main weed of Rio Grande do Sul because of its tough control and often incidence", informs Mário Bianchi, a researcher from Gaúcha Central Cooperative (CCGL), from Cruz Alta, a municipality in the state of Rio Grande do Sul.

Besides it, the inadequate management is one of the main causes of the appearances of weeds that are resistant to certain herbicides. "Resistance is a recurring problem in Brazil, caused mainly by inadequate management in areas where it is common practice and subsequent repeated use of the same or different herbicides, but with the same mechanism of action", adds Fernando Adegas, a researcher of a soybeans unit of Brazil's National Agricultural Research Company in Londrina, state of Paraná.

The cases of resistant weeds first occurred ten years ago in Brazil, with resistance to ryegrass (in 2003) and horseweed (in 2005) to glyphosate. While farmers and researchers have enhanced the mechanisms of management to contain the resistant, among them the repetition of the same herbicide, the problem has evolved for the cases of multiple resistance, or that the same invader became resisted to two different herbicides.

Thus, in 2010 and 2011, ryegrass biotypes resistant to glyphosate were both identified as inhibiting herbicides enzyme Acetyl-CoA carboxylase (ACCase) inhibitors and Acetolactate synthase (ALS). Resistances of ryegrass and horseweed restrict the control of these species, forcing farmers to use alternative herbicides, which are less efficient, have more costs, and also are phytotoxic to the crops. Therefore, the inefficient control of resistant horseweed and ryegrass have resulted in losses of yields, under extreme cases, exceeding 45%.