Characterization of clopyralid resistance in lawn burweed (Soliva sessilis)

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.

Inheritance of dicamba‐resistance in allotetraploid Chenopodium album

“…To confirm the individuals of R population were correctly identified as C. album , the psbA ‐ trnH and ITS regions were sequenced as these regions have been used as barcodes in plant taxonomy to identify plant species 28,29,33 . The results showed that the sequence from both R and S populations were identical to each other for the analysed psbA ‐ trnH and ITS regions, and also matched GenBank entries for C. album (e.g.…”

“…abnormal leaf shape) manifested by the dicamba‐resistant C. album are likely to be associated with the mechanisms of resistance. Abnormalities in leaf shape and development have been documented in some other synthetic auxinic herbicide‐resistant weeds species such as Soliva sessilis Ruiz & Pav 33 . and Sinapis arvensis L 34 …”

“…Abnormalities in leaf shape and development have been documented in some other synthetic auxinic herbicide‐resistant weeds species such as Soliva sessilis Ruiz & Pav. 33 and Sinapis arvensis L. 34 …”

“…Abnormalities in leaf shape and development have been documented in some other synthetic auxinic herbicide-resistant weeds species such as Soliva sessilis Ruiz & Pav. 33 and Sinapis arvensis L. 34 3.2 The level of ploidy in dicamba-resistant C. album Flow cytometry was used to determine the ploidy of both R and S populations of C. album (Fig. 2).…”

A novel mutation in IAA16 is associated with dicamba resistance in Chenopodium album

“…from New Zealand (14-fold). 54 The differences in the resistance level between C. album and B. scoparia from Montana and Soliva sessilis may be due to the presence of different resistance mechanisms.…”