Argentina Apresid confirms Conyza sumatrensis resistance to 3 more molecules

By Leonardo Gottems, Reporter for AgroPages

The Argentine Association of Direct Sowing Producers (Aapresid) published a yellow alert confirming that a black branch biotype (Conyza sumatrensis) developed resistance to the hormonal herbicides 2,4D and Dicamba and the PPO inhibitor saflufenacil.

That weed was already resistant to glyphosate and ALS inhibitors.

The team of consultants and researchers confirmed that this resistance occurs in pre-emergence. "Resistance at this stage is very worrying since this practice is widely used for the control of Black Branch in winter fallows, in winter crops such as wheat and barley and in soy."

"We are facing a new yellow alert for suspected resistance for the Pest Management Network (REM)," Aapresid reported. These herbicides are widely used to control Black Branch in fallows and - in the case of the mentioned hormones - even within winter cereals.

According to the researchers, good control is still recorded by Flumioxazin and Terbutylazine (as pre-emerging herbicides for use on wheat) and Atrazine (fallow to corn). Meanwhile, they say, the possible loss of these valuable active ingredients greatly reduces chemical control alternatives. Another possible strategy is the incorporation of the Doble Knock Down (DKD).

"Black Branch caused numerous problems for producers a few years ago, but by changing the management it was possible to live with it and keep it at bay. With the appearance of resistance to ALS and these new suspicions being confirmed, everything suggests that it will position itself again as one of the most difficult in the years to come," Aapresid said in conclusion.