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    A novel mutation in IAA16 is associated with dicamba resistance in Chenopodium album
    (John Wiley and Sons Ltd on behalf of Society of Chemical Industry, 2024-07) Ghanizadeh H; He L; Griffiths AG; Harrington KC; Carbone V; Wu H; Tian K; Bo H; Xinhui D
    BACKGROUND: Resistance to dicamba in Chenopodium album was first documented over a decade ago, however, the molecular basis of dicamba resistance in this species has not been elucidated. In this research, the resistance mechanism in a dicamba-resistant C. album phenotype was investigated using a transcriptomics (RNA-sequence) approach. RESULTS: The dose-response assay showed that the resistant (R) phenotype was nearly 25-fold more resistant to dicamba than a susceptible (S) phenotype of C. album. Also, dicamba treatment significantly induced transcription of the known auxin-responsive genes, Gretchen Hagen 3 (GH3), small auxin-up RNAs (SAURs), and 1-aminocyclopropane-1-carboxylate synthase (ACS) genes in the susceptible phenotype. Comparing the transcripts of auxin TIR/AFB receptors and auxin/indole-3-acetic acid (AUX/IAA) proteins identified from C. album transcriptomic analysis revealed that the R phenotype contained a novel mutation at the first codon of the GWPPV degron motif of IAA16, resulting in an amino acid substitution of glycine (G) with aspartic acid (D). Sequencing the IAA16 gene in other R and S individuals further confirmed that all the R individuals contained the mutation. CONCLUSION: In this research, we describe the dicamba resistance mechanism in the only case of dicamba-resistant C. album reported to date. Prior work has shown that the dicamba resistance allele confers significant growth defects to the R phenotype investigated here, suggesting that dicamba-resistant C. album carrying this novel mutation in the IAA16 gene may not persist at high frequencies upon removal of dicamba application.
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    Climatic factors affecting herbicidal activity of sodium trichloracetate in different soils : a thesis submitted to the University of New Zealand in partial fulfillment of the requirements for the degree of Master of Agricultural Science (Horticulture)
    (Massey University, 1956) Pengelly, R.
    Trichloracetic acid (T C A) has long been known as a protein precipitant, but it was not until 1947 that research workers in the U.S.A. found it to be an effecive grass killer. Immediately it was subjected to a considerable amount of ex­perimentation, but it is only since 1950 that any trials have been conducted with this herbicide in New Zealand. Most of this early research was of an observational or emperical nature, and the results obtained were often in­consistent. However, it was soon determined that there was little downward translocation of T C A when foliar applications were made, and that for maximum kill it was essential for the herbicide to come into contact with the grass roots. Best control of couch (Agropyron repens L.), for example, has been obtained when the T C A was sprayed on the upturned sod and light rain fell within a few days after application. Before commerical usage of any newly developed herbicide is recommended on agricultural land it is desirable to know the fate of that herbicide when applied to the soil, whether it will persist and be cumulative so that subsequent crops will be effected, if a short period of residual activity can be expected, or if the compound is rapidly dissipated. To this writer's knowledge, no attempt had been made in New Zealand to undertake a quantitative study of the effects soil type, temperature and rainfall have on the rate of inactivation and distribution of T C A when applied to the soil. Such an investigation therefore seemed pertinent, and more especially because results of similar studies overseas were not in full agreement. The published reports showed that both chemical and biological tests had been employed to determine the concentra­tions, or relative amounts of T C A in the soil, but in no instance had the two methods been employed for the one experi­ment. It was therefore considered that in a future investigation some useful purpose would be served by a comparison of results obtained by both tests. [From Introduction]
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    A study of the susceptibility to Dalapon of four common pasture grasses : a thesis presented at Massey Agricultural College in part fulfilment of the requirements for the degree of Master of Agricultural Science in the University of New Zealand
    (Massey Agricultural College, 1959) Lawson, H. M.
    One of the more important developments of recent years in New Zealand agricuture has been the introduction of herbicides selective against grass species. Originally intended for the control of grass weeds in arable crops these herbicides have proved capable of being utilized in many other aspects of farming practice, the most spectacular of which is 'chemical ploughing'. This popular name has been coined to describe the process whereby pastures may be improved with the aid of herbicides on land which cannot succesfully be cultivated by conventional means. Extension of this technique to land which is only accessible to the aeroplane is being investigated by Blackmre (1958) and the preliminary reports suggest that 'chemical ploughing' may be a useful aid to aerial top-dressing and oversowing. Every new development, however striking, must satisfactorily blend with or replace existing practice before it becomes generally accepted. Many problems of practical application require solution before recommenbdations can be made to farmers and there are at present under investigation in field trials throughout the country. At the same time a thorough knowledge of the properties of the herbicides and the factors affecting their efficiency under a wide range of field conditions is essential. Where herbicides are applied to a mixed population of plants, as in a pasture, it is desirable to know, within fairly narrow limits, the tolerance of each constituent species. The experiments reported in this thesis were undertaken to investigate the susceptibility of some common pasture species to dalapon, the most important of the selective grass-killing herbicides involved in 'chemical ploughing' and associated techniques.
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    Some properties of SENCOR (Metribuzin) and bases for variation of its effect on Solanum nigrum and Solanum sarachoides : a thesis presented in partial fulfilment of the requirements for the degree of Master of Horticultural Science in Plant Science
    (Massey University, 1974) Amaranthan, Balasingham
    In Part I of this study, the relative potencies of SENCOR and its metabolites have been investigated. SENCOR has been established as a potent Hill reaction inhibitor. The observed action of SENCOR and its metabolites are discussed in terms of structure/activity relationship The mechanism of action of SENCOR and one of its metabolites is compared with other known Hill reaction inhibitors. A scheme is then proposed for the mode of action of Hill reaction inhibitors. In Part II the observed variation in the field, in the response of Solanum nigrum and Solanum sarachoides to SENCOR has been established as a phenomena of species selectivity From studies on uptake, distribution and metabolism of radio active SENCOR it has been established that a restriction to movement of the herbicide from the xylem to the mesophyll occurs in Solanum sarachoides (tolerant species) while the material is distributed throughout the mesophyll in the susceptible Solanum nigrum. This restriction to movement into the mesophyll in the tolerant species has been confirmed by studies on the inhibition of rate of transpiration and from effects on stomata. SENCOR also appears to be metabolised to a greater extent in the tolerant species This study leads to the conclusion that the protection of the active centre, the chloroplasts, through restriction to movement of SENCOR into the mesophyll, combined with partial breakdown of the herbicide in the plant may be responsible for the tolerance of Solanum sarachoides to SENCOR.
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    Chemical control of Poa trivialis on New Zealand racetracks : a thesis presented in partial fulfilment of the requirements for the degree of Master of Applied Science at Massey University
    (Massey University, 1996) Fleming, Philip Brian
    Poa trivialis is a perennial grass weed commonly found in perennial ryegrass (Lolium perenne) racetrack swards throughout New Zealand. Its presence is undesirable as it does not tolerate high wear and is susceptible to dying out over the summer. Two pot trials at Massey University and one field trial carried out at the Awapuni racecourse were conducted during winter and spring 1995 to test the relative susceptibility of Poa trivialis and perennial ryegrass to a wide range of herbicides. A bioassay was also conducted to determine whether herbicide residues from the field trial could affect the germination of perennial ryegrass seed sown soon after treatment. Results showed that none of the chemicals at their chosen respective rates could completely remove Poa trivialis from a racetrack sward in the spring without some damage being caused to perennial ryegrass. Propyzamide and fenoxaprop at rates of 0.2 and 0.15 kg/ha respectively showed the most potential of the chemicals, severely damaging Poa trivialis (causing 50 to 75% reductions) with no adverse effect on perennial ryegrass 8 weeks after spraying. Propyzamide can also provide some control of Poa annua. Fenoxaprop was not improved by increasing the application rate or adding an oil. The performance of fenoxaprop was substantially reduced when applied with either MCPA or a picloram/triclopyr mix. Dalapon and asulam showed good potential to control Poa trivialis but at the high rates tested caused variable or harmful effects to perennial ryegrass. Ethofumesate and chlorpropham applied at rates of 2.0 and 2.5 kg/ha respectively gave inadequate control of Poa trivialis. None of the above herbicides, when used in the field trial resulted in residues which reduced the germination of perennial ryegrass seed sown 3 weeks after spraying. Herbicides tested in the pot trials which showed poor control of Poa trivialis were atrazine, dicamba, isoproturon/diflufenican, linuron, mecoprop, methabenzthiazuron, metsulfuron, pendimethalin, prometryne, thifensulfuron-methyl, triclopyr, and trinexapac-ethyl. Diuron applied at 2.6 kg/ha provided good control of Poa trivialis but caused significant damage to perennial ryegrass. It is concluded that an integrated management approach that incorporates both cultural and chemical techniques will be required to control Poa trivialis on New Zealand racetracks. Future trial work should be carried out on propyzamide applied at rates of 0.2-0.3 kg/ha in autumn to establish the most appropriate time of year to apply this herbicide.
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    Ground cover plants for weed control in amenity horticulture : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Plant Science at Massey University, Palmerston North, New Zealand
    (Massey University, 2012) Foo, Chin Lui
    Aspects of the establishment and use of ground cover plants for urban weed control were investigated. Established ground cover populations of different taxa were monitored over 1 year at 14 sites for their ability to block light from the soil and prevent weeds from establishing. Field trials compared 12 ground cover species of widely differing growth form for rate of establishment and ability to block light and suppress weeds. Another field trial compared various types of mulch with selective herbicides and hand weeding as techniques for establishing ground cover species. No single growth form was superior to others, and it was the density of the foliage that was key to suppressing weeds. Ground cover plants should be selected for having persistently dense canopies throughout the year, such as Coprosma acerosa ‘Taiko’ and Juniperus procumbens. Deciduous species like Persicaria capitata, evergreen species which become sparser in winter like Pimelea prostrata, and plant canopies which open up during flowering like Grevillea lanigera, all allow weeds to germinate while the ground is exposed. Ground cover plants appear to deter weeds mainly by keeping weed seeds dormant through preventing red light from reaching weed seeds and triggering a phytochrome response leading to germination. Keeping the ratio of red to far-red light below 0.3 appeared to give best inhibition of weed seed germination. Presence of mulch and spot application of selective herbicides can help prevent weeds causing problems should gaps appear within ground covers, and these may be preferable to hand weeding. Little herbicide tolerance information exists for ornamental ground cover plants, so herbicide tolerance trials were conducted on eight ground cover plant species. This work showed that herbicides can aid in ground cover plant establishment and subsequent maintenance to selectively spot-treat weeds that appear. Ground cover species were assessed which grow low enough to be mowed but which seldom need mowing, to replace grass turf in situations where mowing is inconvenient such as under trees, on slopes, or roadsides. Dichondra micrantha and Soleirolia soleirolii showed the most potential, forming dense low growing swards that tolerated a wide range of herbicides.
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    An activated sludge based system for the treatment of leachate containing chlorophenols and phenoxyacetate herbicides : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Biotechnology at Massey University
    (Massey University, 1990) McAllister, Peter James
    A study was made on the biological treatment of a landfill leachate containing high concentrations of the phenoxy herbicides 2,4-dichlorophenoxyacetic acid (2,4-D), 2-methyl-4-chlorophenoxyacetic acid (MCPA) and 2,4,5-trichlorophenoxyacetic acid (2,4,5-T), along with significant quantities of para-chloro-ortho-cresol (PCOC), methanol, butan-1-ol and butan-2-ol. A mixed, natural microbial population (consisting of Pseudomonas species) was developed from a soil inoculum. The culture was found to be capable of mineralising 2,4-D and reducing the toxicity of the leachate by 92 %. The culture was found to be stable in continuous culture (residence time = 14.5 h) for 872 days. The optimum concentrations for degradation were found to be 5-10% leachate (217-435 mg/l phenoxies, 33-66 mg/l PCOC, 40-80 mg/l alcohols and 0.6-1.2 g/l ash) for batch work and 10-15 % leachate (435-708 mg/l phenoxies, 66-107 mg/l PCOC, 80-120 mg/l alcohols and 1.2-1.9 g/l ash) for CSTR work. Batch studies showed sequential utilisation of the substrates: alcohols, followed by PCOC followed by phenoxies. Studies were carried out to determine the kinetics of degradation for each group of substrates. The results showed that alcohols were the most rapidly degraded (μMAX = 0.3 h-1), although growth was inhibited by PCOC and phenoxies. PCOC was inhibitory to its own degradation, with inhibition directly proportional to PCOC concentration up to 290 mg/l, above which no degradation occurred. Both alcohol and PCOC degradation were described well by a linear inhibition model. A comparison was made between the batch determination of PCOC degradation kinetics and a relatively new method, the Modified Infinite Dilution Test (MIDT). The MIDT results showed rates 50 % higher than the batch methods, indicating there was a change in the nature of the biomass in batch studies. The kinetics of phenoxy degradation indicated that there was no inhibition in the concentration range of interest for MCPA and 2,4-D. However, 2,4.5-T was apparently degraded by cometabolism, with PCOC the best stimulator of degradation. An interactive three substrate model was used to describe degradation and was found to fit measured data for CSTR systems. The model was robust and could predict the single substrate (ie pure compound kinetics) on simplification, indicating the wide range of application of the model. The model showed that the presence of the alcohols in leachate considerably accelerated the degradation of PCOC and phenoxies. Critical points for washout were significantly shifted and reversed from those of pure compounds, indicating interactions between the substrates could not be ignored. The model provides a method for quantifying the effect of a secondary substrate on the target compounds. Results from laboratory activated sludge experiments showed that this process was capable of degrading the alcohols, PCOC and phenoxies present in both 10 and 15 % leachate. Loading rates (1.9-3.0 kgsubstrate/m3.d) were high in comparison to the typical loadings quoted in the literature. The three substrate model, in association with the critical point method predicted three regions of plant operation, total substrate removal, stable operation with residual substrate and no degradation, compared with the two regions of the critical point method. The results also showed that the system could be treated as non-inhibitory for design purposes, as the Monod model gave a closer prediction of behaviour than the critical point method. However, as the composition of the leachate is expected to change, the three substrate model is required to predict the effect of these changes on an AS plant. The sludge produced by the AS plant had low concentrations of residual organic and inorganic ions, indicating it could be treated as a non-hazardous byproduct. While AS reduced the toxicity by 71 %, the effluent toxicity could be reduced further by the use of activated carbon treatment. This produced a final effluent with an EC50 (48h) of 46 %. Preliminary economic analysis showed that AS followed by activated carbon treatment was capable of treating the leachate for 42c/l. lower than the alternatives of activated carbon alone and incineration. The cost was most sensitive to leaching rate, with lower rates resulting in smaller and cheaper processes. To conclude, it was shown that a biologically based process is capable of producing non-hazardous byproducts and is economically viable as compared to alternative treatment processes.