Brassica rapa L. is an important weed in winter wheat, barley, and other winter crops, and its control has become more difficult due to the development of resistant biotypes. The aim of this study was to record the presence of a B. rapa biotype resistant to 2,4-D herbicides and to evaluate the effect of different formulations of 2,4-D and other auxin herbicides on this biotype. Three independent dose-response experiments were conducted to evaluate: (i) the sensitivity of the resistant and susceptible B. rapa biotypes to increasing doses of 2,4-D, (ii) the sensitivity of the resistant biotype to different formulations of 2,4-D (butyl ester, dimethylamine salt, acid, and choline salt), and (iii) the sensitivity of the resistant biotype to other auxinic herbicides (picloram, dicamba, fluroxypyr, clopyralid and MCPA). The B. rapa resistant biotype showed a resistance index of 4.7, which means that, to achieve 50% inhibition of survival, the dose required needs to be approximately five-fold higher that required for the susceptible biotype. The GR₅₀ of the resistant biotype for the different 2,4-D formulations marketed in Argentina was variable. The 2,4-D acid microemulsion formulation was the product that showed the highest control efficiency and biomass reduction. The resistant biotype was not susceptible to clopyralid, dicamba, or picloram, with maximum phytotoxicity of 25%, even when treated with four times the recommended dose and without biomass reduction, showing cross-resistance.

甘蓝型油菜（Brassica rapa L.）是冬小麦，大麦和其他冬季作物中的一种重要杂草，由于抗性生物型的发展，其控制变得更加困难。这项研究的目的是记录对2,4-D除草剂有抗性的B. rapa生物型的存在，并评估不同制剂的2,4-D和其他生长素除草剂对该生物型的影响。进行了三个独立的剂量反应实验以评估：（i）抗药性和易感双歧杆菌的敏感性生物型对增加剂量的2,4-D的敏感性；（ii）抗性生物型对2,4-D的不同制剂（丁酯，二甲胺盐，酸和胆碱盐）的敏感性，以及（iii）对对其他植物生长素类除草剂（吡咯兰，麦草畏，氟草烟，氯吡格雷和MCPA）具有抗性。的芜菁抗生物型显示出4.7阻力指数，这意味着，为了实现的存活的50％的抑制，其中，所述剂量所需的需要是大约五倍高于所需的易感生物型。GR ₅₀在阿根廷销售的不同2，4-D制剂的抗药性生物型的差异是可变的。2,4-D酸微乳液配方是具有最高控制效率和减少生物质的产品。即使以建议剂量的四倍处理且没有减少生物量的情况下，抗药性生物型也不易受到氯吡吡兰，麦草畏或吡咯烷的影响，最大植物毒性为25％，表现出交叉抗性。