https://orcid.org/0000-0001-5381-7880
Herbicide resistance in weeds is currently the most prominent research topic within the field of weed science, reflecting the importance of the issue and the concerns over its threat to global food production. Since the first case of herbicide resistance in New Zealand in the late 1970s, the number of cases has increased markedly, with some weeds having evolved resistance to multiple modes of action of herbicides (Ghanizadeh and Harrington Citation2021). In 2018, a five-year project funded by the Ministry of Business, Innovation and Employment (MBIE), was initiated to focus on improved weed control and vegetation management to minimise future herbicide resistance in New Zealand. This special issue presents some recent work by the researchers involved in that programme. The seven manuscripts published in this special issue cover a range of various aspects of basic and applied research on herbicide resistance and weed management.
Although the number of herbicide-resistant weed populations is increasing in New Zealand, there is a significantly lower incidence of herbicide resistance in New Zealand compared to many other countries, including Australia. Harrington and Ghanizadeh (Citation2023) provide a glimpse into some of the reasons for these differences between New Zealand and Australia to help with the future management of herbicide resistance in New Zealand. Nevertheless, the lower incidence of herbicide resistance recorded in New Zealand does not imply any future resistance development risk. However, identifying weed species most likely to develop herbicide resistance in new regions is challenging. By using state-of-the-art mathematical analyses and data science, Hulme (Citation2023) developed a machine-learning tool to assess which weed species pose the greatest risk of becoming herbicide-resistant. This tool can facilitate the predictions of the next herbicide-resistant weed in New Zealand.
Before the programme's beginning, herbicide resistance reporting had primarily been ad-hoc and left to growers and rural professionals to recognise and alert researchers (Buddenhagen et al. Citation2021). Buddenhagen et al. (Citation2023) believe this ad-hoc reporting has possibly led to an historical underestimation of the extent of the herbicide resistance problem in New Zealand. As proof of concept, they ran random surveys across various arable farms in New Zealand and found unique cases of herbicide-resistant weeds previously unidentified in New Zealand. They also found multiple resistance to Group 1, ACCase (acetyl CoA carboxylase)-inhibitors and Group2, ALS (acetolactate synthase)-inhibitors in several populations of Lolium spp. (ryegrass). Further investigation by Ghanizadeh et al. (Citation2022a) revealed that resistance to ALS-inhibitors in one of the ryegrass populations was due to target enzyme modification and enhanced herbicide metabolism through cytochrome P450. Previously, it was also shown that the enhanced herbicide metabolism mechanism through cytochrome P450 also conferred resistance to ACCase-inhibitors in the same ryegrass population (Ghanizadeh et al. Citation2022b), suggesting the same mechanism is likely to be associated with resistance to both herbicide groups. An outcome from these findings is Buddenhagen et al. (Citation2023) recommending the establishment of an herbicide resistance testing services to facilitate monitoring herbicide resistance and provide further insights into the extent of the problem in New Zealand.
The primary step in managing herbicide-resistant weeds is to confirm their resistance (Burgos Citation2015). The conventional method for confirming herbicide-resistance is whole-plant spray assays. However, this method is time-consuming and expensive when many samples need to be assessed. Ghanizadeh et al. (Citation2023) developed two high-throughput rapid molecular diagnostic assays for detecting target-site mutations in glyphosate-resistant Lolium perenne. They also discussed the advantages and disadvantages of their high-throughput molecular diagnostic assays compared to a formerly developed molecular diagnostic assay (Ghanizadeh et al. Citation2021), and made recommendations on selecting a proper molecular diagnostic assay based on the research objectives.
Herbicides are the most commonly used tools for weed management, but alternative non-chemical approaches are desired, given that over-reliance on herbicides has resulted in the development of herbicide-resistant weeds (Melander et al. Citation2017). Non-chemical weed management is the topic of Bloomer et al. (Citation2023) and Trolove et al. (Citation2023) in this special issue. The former group reviewed non-herbicide weed control options, including robotic weed management, and discussed the potential of using pulsed electric micro shocks (Bloomer et al. Citation2022), as a very low-energy option for an integrated weed management system. Trolove et al. (Citation2023) discuss the results of a multi-year field trial on using cover crops to reduce herbicide input in maize crops. They noted that integrating a vigorous large-seeded legume winter cover crop into spring-planted maize pastoral systems promoted yields and provided good weed suppression. They also noted that using vigorous large-seeded legume winter cover crops reduced the number of herbicides applied to maize to a single post-emergence application.
Together, the manuscripts in this special issue reflect some of the current focus in herbicide resistance research and the wide collaboration across universities, research institutes and the agricultural industry in New Zealand. The Editors are grateful to the authors, their funders, reviewers and the publishing office who have contributed to the publication of this special issue.
Disclosure statement
No potential conflict of interest was reported by the author(s).
References
- Bloomer DJ, Harrington KC, Ghanizadeh H, James TK. 2022. Micro electric shocks control broadleaved and grass weeds. Agronomy. 12(9):2039. doi:10.3390/agronomy12092039.
- Bloomer DJ, Harrington KC, Ghanizadeh H, James TK. 2023. Robots and shocks: emerging non-herbicide weed control options for vegetable and arable cropping. New Zeal J Agric Res. doi:10.1080/00288233.2023.2252769.
- Buddenhagen CE, James TK, Ngow Z, Hackell DL, Rolston MP, Chynoweth RJ, Gunnarsson M, Li F, Harrington KC, Ghanizadeh H. 2021. Resistance to post-emergent herbicides is becoming common for grass weeds on New Zealand wheat and barley farms. PLOS ONE. 16(10):e0258685. doi:10.1371/journal.pone.0258685.
- Buddenhagen CE, Ngow Z, James T, Harvey B, Gunnarsson M, Ghanizadeh H, Rolston MP. 2023. The value of a herbicide resistance testing service for the agricultural sector in New Zealand. New Zeal J Agric Res. doi:10.1080/00288233.2023.2209328.
- Burgos NR. 2015. Whole-plant and seed bioassays for resistance confirmation. Weed Sci. 63(sp1):152–165. doi:10.1614/WS-D-14-00019.1.
- Ghanizadeh H, Anderson CB, Franzmayr BK, Cook M, Buddenhagen CE, Ngow Z, James TK, Griffiths AG. 2023. Evaluation of high-resolution melting and RT-qPCR probe assays for high-throughput detection of target-site mutations conferring glyphosate resistance in Lolium perenne. New Zeal J Agric Res. doi:10.1080/00288233.2023.2218099.
- Ghanizadeh H, Buddenhagen CE, Griffiths AG, Harrington KC, Ngow Z. 2022a. Target-site and non-target site resistance mechanisms are associated with iodosulfuron resistance in Lolium perenne L. New Zeal J Agric Res. doi:10.1080/00288233.2022.2153875.
- Ghanizadeh H, Buddenhagen CE, Harrington KC, Griffiths AG, Ngow Z. 2022b. Pinoxaden resistance in Lolium perenne L. is due to both target-site and non-target-site mechanisms. Pestic Biochem Phys. 184:105103. doi:10.1016/j.pestbp.2022.105103.
- Ghanizadeh H, Griffiths AG, Buddenhagen CE, Anderson CB, Harrington KC. 2021. A PCR plus restriction enzyme-based technique for detecting target-enzyme mutations at position Pro-106 in glyphosate-resistant Lolium perenne. PLOS ONE. 16(2):e0246028. doi:10.1371/journal.pone.0246028.
- Ghanizadeh H, Harrington KC. 2021. Herbicide resistant weeds in New Zealand: state of knowledge. New Zeal J Agric Res. 64(4):471–482. doi:10.1080/00288233.2019.1705863.
- Harrington KC, Ghanizadeh H. 2023. Comparing herbicide resistance in New Zealand and Australia. New Zeal J Agric Res. doi:10.1080/00288233.2023.2180759.
- Hulme PE. 2023. Potential risks of future herbicide-resistant weeds in New Zealand revealed through machine learning. New Zeal J Agric Res. doi:10.1080/00288233.2023.2210288.
- Melander B, Liebman M, Davis AS, Gallandt ER, Bàrberi P, Moonen A-C, Rasmussen J, van der Weide R, Vidotto F. 2017. Non-chemical weed management. In: Hatcher PE, Froud-Williams RJ, editor. Weed research: expanding horizons. Oxford, UK: Wiley; p. 245–270.
- Trolove MR, James TK, BH W-J, Henderson HV, Gerard PJ. 2023. Winter cover crops to reduce herbicide inputs into spring-planted maize pastoral systems in New Zealand. New Zeal J Agric Res. doi:10.1080/00288233.2023.2193413.