Abstract
Soliva sessilis is a troublesome annual weed species in New Zealand turfgrass. This weed has been controlled selectively in New Zealand turfgrass for many years using pyridine herbicides such as clopyralid. However, in some golf courses, the continuous application of pyridine herbicides has resulted in the selection of S. sessilis populations that are resistant to these herbicides. This study focuses on a clopyralid-resistant population of S. sessilis collected from a golf course with a long history of clopyralid applications. The resistant phenotype of S. sessilis was highly resistant to clopyralid (over 225-fold). It was also cross-resistant to dicamba, MCPA and picloram but not mecoprop. The level of resistance to dicamba was high (7-14-fold) but much lower (2-3-fold) for both MCPA and picloram. The phenotype was morphologically distinct from its susceptible counterpart. Individuals of the clopyralid-resistant phenotype had fewer lobes on their leaves and were slightly larger compared to the susceptible phenotype. Resistant individuals also had a larger leaf area and greater root dry weight than the susceptible plants. An evaluation of internal transcribed spacer (ITS) regions confirmed that clopyralid-resistant phenotypes are conspecific with S. sessilis. In summary, the cross-resistance to several auxinic herbicides in this S. sessilis phenotype greatly reduces chemical options for controlling it; thus, other integrated management practices may be needed such as using turfgrass competition to reduce weed germination. However, the morphological differences between resistant and susceptible plants make it easy to see, which will help with its management.
Highlights
Weeds are unwanted plant species that can be troublesome in agricultural and non-agricultural situations [1]
While all OS plants treated at 300 g ae clopyralid ha-1 were completely dead at 4 weeks after application, even 4800 g ae clopyralid ha-1 did not cause any mortality in the plants of one. The clopyralid-resistant population (OR) population (Fig 1A, Table 2)
The ITS2 region sequence of population OR had 95.50, 94.0 and 90.80% homology with that of S. anthemifolia, S. mutisii and Soliva stolonifera, respectively (Fig 5). These results showed that individuals of population OR had identical internal transcribed spacer (ITS) region sequences with S. sessilis and the ITS2 region appeared to provide higher identification efficiency compared to the ITS1 region
Summary
Weeds are unwanted plant species that can be troublesome in agricultural and non-agricultural situations [1]. Since the first herbicide was commercialized, chemical weed control has been the preferred method for managing weed populations [2]. The popularity of herbicides for weed control has not been without consequences and as predicted in the early days of the commercialization of herbicides, the occurrence of herbicide resistance in weed populations was inevitable [3]. To date there are over 500 unique cases of herbicide-resistant weed species globally [4]. In New Zealand, currently there are 25 confirmed cases of herbicide-resistant weeds [5], two of which were reported in turfgrass [6, 7]. A member of the Asteraceae family, is a low growing winter annual weed species [8]. S. sessilis is originally from South America [9], and some of its common names include
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
