Our latest paper “No auxinic herbicide-resistance cost in wild radish (Raphanus raphanistrum)” by Goggin, Beckie, Sayer & Powles, was published in Weed Science, 2019, 67, 539-545.
There is great difficulty in understanding the initial effects of auxinic herbicides on plants. Therefore, research on understanding the mechanistic basis of auxinic herbicide resistance in plants is very difficult. This is especially so in a genetically diverse cross-pollinated species like wild radish. We should expect diversity in resistance mechanisms and AHRI researcher Dr Danica Goggin in researching the mechanistic basis of auxinic herbicide resistance has revealed this complexity in wild radish (Goggin et al, Annals of Botany 2018, 122, 627-640), with her paper “2,4-D and dicamba resistance mechanisms in wild radish: subtle, complex and population-specific”.
In this study, Danica Goggin used 11 very well characterised resistant wild radish populations and two susceptible populations grown in the presence and absence of competition from wheat so as to examine for any auxinic herbicide resistance fitness cost. She found no evidence of a fitness cost. The two susceptible and 11 resistant populations were equally suppressed by wheat competition, with growth and seed production equally reduced by competition. Thus, across these 11 resistant populations that had all been earlier studied at the mechanistic level (Goggin et al 2018), there was no evidence of a fitness cost associated with auxinic herbicide resistance.
This research was supported by an Australian Research Council grant, with Nufarm as a linkage partner.