Kerry Charles Harrington

• PhD in Weed Science
• Professor (Associate) at Massey University

Opportunistic use of limited resources is often attributed to invasive species, and as a mature vine, old man’s beard ( Clematis vitalba L.) is known to have devastating negative impacts on the trees it colonizes. No previous experimental studies have been published on how easily C. vitalba seedlings can colonize ground covered by other established...

Seeking low environmental impact alternatives to chemical herbicides that can be integrated into a regenerative agriculture system, we developed and tested flat-plate electrode weeding equipment applying ultra-low-energy electric shocks to seedlings in the field. Better than 90% control was achieved for all species, with energy to treat 5 weeds m⁻²...

Identifying characteristics of invasive species or growth forms that facilitate their range expansion is critical for management. Clematis vitalba L. (old man's beard) is an invasive temperate liana in many areas of its introduction, yet its seedlings do not thrive in circumstances where resources are limited. Although some lianas in both tropical...

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...

Old man's beard ( Clematis vitalba L.) is a liana species that has become invasive in many areas of its introduced range. Seeds are produced in abundance and are both physiologically and morphologically dormant upon maturity. To understand the importance of seeds to its invasiveness, changes in viability and dormancy of the aerial seed bank were tr...

Seeking an easy-to-deploy, energy-efficient, non-herbicide weed control method, we tested a flat-plate electrode to apply pulsed electric microshocks (PMS) to a grass and four broadleaf weed species. The method can be deployed via a hand-held unit or as part of a fully automated system to control escape weeds in field crops. The effectiveness of th...

For decades, herbicides have provided easy-to-use, cost-effective weed management, but alternatives are desired. Consumer preference for chemical-free food, awareness of environmental impacts, regulation increasingly restricting agrichemical use, and increasing prevalence of herbicide resistance are forcing changes to weed management strategies....

Old man’s beard is a woody liana that has become an invasive weed in many areas of its introduction, through its vigorous spread and negative impacts on the tree hosts it climbs. Control techniques that improve precision and reduce non-target damage are increasingly preferred for weed control yet have not been compared in published research for use...

Although New Zealand is developing an increasing number of herbicide-resistant weed populations, it has a much lower incidence of herbicide resistance than Australia. Understanding the reasons for these differences may help with future management of herbicide resistance in both countries. Australia is much larger than New Zealand so greater areas o...

Resistance to iodosulfuron, a herbicide targeting acetolactate synthase (ALS), was identified and characterised in a population of Lolium perenne L. from Canterbury, New Zealand. The resistant population was 264 times more resistant to iodosulfuron than a susceptible population, based on a ratio of the rate corresponding to a 50% reduction in resis...

Wiper applicators allow herbicides to be selectively delivered to upright target weeds, thereby avoiding application to nearby lower-growing desirable pasture plants. In this research, we investigated the efficacy of wiper application of four herbicides, clopyralid, metsulfuron, glyphosate and a triclopyr/picloram mixture, to control Cirsium arvens...

A search for energy efficient, non-herbicide weed control methods led to development of a novel electrical weeding technology. This study focuses on weed control efficiency and energy as elements of a system that would include machine vision and robotics to control escape weeds in field crops. Two pulse generation systems, one single and one multip...

BACKGROUND Chenopodium album L. is a troublesome weed in spring‐planted crops, and different levels of ploidy have been documented for this weed species. A population of C. album has evolved resistance to dicamba. The level of ploidy and inheritance of dicamba resistance was studied in this population. RESULTS The resistant and susceptible individ...

Pastures represent about half of the global agricultural area and productivity losses from weeds are significant. The complex interactions between them and other pasture plants, livestock and the environment imply a need for innovative research that transforms pasture management. To this end, a horizon scan was conducted to identify relevant issues...

Leaching of herbicides in cropping soils not only impacts the groundwater sources but also reduces their effect in controlling weeds. Leaching studies were carried out in two cropping soils and two forestry biowaste media, wood pulp and sawdust with two herbicides, atrazine and bromacil in a packed lysimeter with simulated rainfall. The hypothesis...

Enhanced herbicide metabolism Herbicide resistance Target-site mechanism Weed management A B S T R A C T Application of herbicides inhibiting acetyl CoA carboxylase (ACCase) has been one of the main strategies for selectively controlling grass weed species such as perennial ryegrass (Lolium perenne L.) in wheat and barley crops in New Zealand. In t...

To estimate the prevalence of herbicide-resistant weeds, 87 wheat and barley farms were randomly surveyed in the Canterbury region of New Zealand. Over 600 weed seed samples from up to 10 mother plants per taxon depending on abundance, were collected immediately prior to harvest (two fields per farm). Some samples provided by agronomists were teste...

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...

The persistence and degradation of two common herbicides, atrazine and bromacil in two organic media, wood pulp and sawdust were compared with two soils. The hypothesis tested was that herbicide degradation will be faster in high organic matter media compared to soil. Degradation of two herbicides was carried out in four different temperature regim...

The first step in managing herbicide-resistant weeds is to confirm their resistance status. It is, therefore, crucial to have a rapid, reliable and cost-effective technique to assess samples for herbicide resistance. We designed and evaluated three derived cleaved amplified polymorphic sequence (dCAPS) markers for detecting glyphosate resistance in...

The evolution of resistance to herbicides in weeds has become a great challenge for global agricultural production. Weeds have evolved resistance to herbicides through many different physiological mechanisms. Some weed species are known to secrete herbicide molecules from roots into the rhizosphere upon being treated. However, root exudation of her...

Haloxyfop is one of two acetyl-coenzyme A carboxylase (ACCase) inhibitors that is recommended for controlling Poa annua. We have characterised a population of P. annua that had developed resistance to haloxyfop. This resistant population was found to be almost 20 times less sensitive to haloxyfop than a susceptible population based on percentage su...

Herbicide-resistant weeds are serious threats to agricultural production. Since a review published in 1996, the number of different examples of weed biotypes developing resistance to one or more herbicides in New Zealand has almost quadrupled. By 1996, six weed species had been shown to have developed resistant biotypes, mostly to either triazine o...

The number of herbicide-resistant weeds is increasing globally. A successful management practice requires an understanding of how resistance traits are inherited. Weed scientists worldwide have investigated the mode of inheritance for herbicide resistance in weeds. Depending on the resistance gene/mechanism, varied patterns of inheritance have been...

The sap-sucking lace bug Gargaphia decoris Drake (Hemiptera: Tingidae) is a biological control agent released in New Zealand to control the invasive small tree or shrub Solanum mauritianum Scopoli (Solanaceae). The aim of this study was to investigate the effect of temperature, photoperiod and humidity on selected G. decoris life history traits. Th...

The alleles responsible for herbicide resistance in weeds can result in a fitness cost within affected plants. Over 200 cases of resistance to triazine herbicides have been confirmed in a wide range of weed species globally. In New Zealand, Chenopodium album L. was the first species reported as resistant to triazines. Several studies have already s...

In New Zealand, pastoral farming for dairy and meat production is the major land use. As with any agricultural production system, weeds are a threat to efficient pasture production in New Zealand. In this review, we outline the problems caused by weeds in New Zealand pastures, and the management strategies being used to control them. There are curr...

Great bindweed (Calystegia silvatica) invades riparian plantings in New Zealand but little is known about the factors influencing seed germination of this species, the number of seeds produced per flower or whether seed banks build up in the soil below infested sites. Dormancy-breaking treatments involving scarification and/or pre-chilling of seeds...

Acetyl-coenzyme A carboxylase (ACCase) inhibitors such as haloxyfop, pinoxaden and clethodim selectively control grass weed species in many types of crop. Here, we characterised two populations of Lolium multiflorum (Italian ryegrass), R and RV, from South Canterbury and Central Otago respectively, that were suspected to be resistant to ACCase-inhi...

Main conclusion Detrimental pleiotropic effects of resistance mutation(s) were observed for multiple-resistant phenotypes (resistant to both atrazine and dicamba). The multiple-resistant phenotypes had lower growth rates and less capacity for vegetative growth compared to the phenotypes only resistant to atrazine. The fitness costs that are conferr...

Organic soil amendments can be useful for improving degraded soil, but this increase in organic matter (OM) may influence adsorption of herbicides subsequently applied to the treated soil, even though the particle size of amendments and their nature differ from typical soil OM. In this study, a batch equilibrium method was used to measure adsorptio...

Forage management underpins the viability of pastoral dairy systems. This review investigated recent developments in forage research and their potential to enable pastoral dairy systems to meet the challenges that will be faced over the next 10 years. Grazing management, complementary forages, pasture diversity, fertiliser use, chemical restriction...

Grass ground covers are often used in forestry to suppress weed germination, but little is known on how best to use grasses to suppress broom (Cytisus scoparius). In this field study, three grass species, Yorkshire fog (Holcus lanatus), Italian ryegrass (Lolium multiflorum) and perennial ryegrass (Lolium perenne), were sown at three rates in autumn...

Chenopodium album is a troublesome arable weed species which has evolved resistance to dicamba in New Zealand. The objective of this work was to investigate the patterns of absorption, translocation and metabolism of dicamba in resistant and susceptible C. album populations. No significant differences in absorption by the two populations were measu...

The mode of inheritance for herbicide resistance was investigated in a population of Lolium multiflorum (Italian ryegrass) with restricted glyphosate translocation mechanism of resistance. The degree of dominance for glyphosate resistance in Italian ryegrass was evaluated in the progenies of F1 families which were created by reciprocal-crossing bet...

Wiper applicators allow herbicides to be directly transferred onto the surface of target plants, thereby avoiding application to nearby desirable plants of shorter stature. This form of herbicide application can greatly reduce costs of weed control and risks of environmental contamination. The risk of drift to susceptible plants in areas adjacent t...

Sequestration of herbicide into vacuoles is considered to be the main mechanism of resistance to both glyphosate and paraquat worldwide. In New Zealand, the first case of glyphosate resistance was found in ryegrass (Lolium) species, and the restricted herbicide translocation was found to be the main mechanism of resistance in the studied population...

Spot-spraying weeds in pastures enables the use of herbicide that would be too harmful to pasture if boom-sprayed. However, some herbicides are more damaging than others. To quantify this damage, a range of spot-spraying treatments was applied to ryegrass/white clover pastures. Four herbicide treatments were compared, each at two application rates...

Sequestration of herbicide into vacuoles is considered to be the main mechanism of resistance to both glyphosate and paraquat worldwide. In New Zealand, the first case of glyphosate resistance was found in ryegrass (Lolium) species, and the restricted herbicide translocation was found to be the main mechanism of resistance in the studied population...

Evolutionary physiology merges the disciplines of evolution and physiology, and it is a research approach that has not received much attention for studying the development of herbicide resistance. This paper makes a case for using evolutionary physiology more frequently when studying herbicide resistance, and illustrates this using three areas wher...

Evolution of resistance in weeds to herbicides is threatening world agricultural production. Weed management has become more complicated with the development of non-target site resistance (NTSR) to herbicides in weeds. The NTSR mechanisms can be caused by herbicide metabolism, altered patterns of translocation, and herbicide absorption/penetration....

Background Broom (Cytisus scoparius (L.) Link) is an invasive weed in many commercial radiata pine (Pinus radiata D.Don) plantations throughout New Zealand. A variety of herbicides are available to selectively control young established broom plants during the first year after planting pines, but there is little published information describing whic...

The responses of two dicamba-resistant Chenopodium album (fathen) populations (L and M) were compared with the responses of two dicamba-susceptible populations (A and P) to the auxinic herbicides mecoprop, clopyralid, 2,4‐D and aminopyralid in a preliminary experiment. The dicamba-resistant fathen was cross-resistant to the pyridine carboxylic acid...

Weed wipers have been used to apply herbicides selectively to tall weeds in pastures for several decades, but few reliable techniques exist to quantify the relative output of wiper applicators under varying operating conditions. A new technique is described in which clopyralid is applied by wiper applicators to plastic sleeves on uniform, upright,...

Wiper application of herbicides to weeds sometimes causes damage to pasture plants, especially white clover, growing immediately under the wiped weeds. Two experiments were conducted to determine the potential for either exudation of herbicide from roots or rainfall washing herbicide off treated plants to cause damage to white clover after wiper ap...

Glyphosate resistance has been found in two populations of Italian ryegrass (Lolium multiflorum) following many years of glyphosate application in New Zealand vineyards. Dose-response experiments showed that both glyphosate-resistant Italian ryegrass populations had 10-fold levels of resistance to glyphosate compared to a susceptible population. Po...

One of the crucial factors in the evolution of herbicide resistance in weeds is the mode of inheritance. Experiments were conducted to determine the inheritance of glyphosate resistance in a population of perennial ryegrass (Lolium perenne) caused by restricted glyphosate translocation. First, the degree of dominance of the glyphosate resistance tr...

In 2013, three populations of perennial ryegrass (Lolium perenne) and two populations of Italian ryegrass (L. multiflorum) from five vineyards in New Zealand were confirmed to be resistant to glyphosate. The level of resistance in four populations was almost 10-fold while one population of perennial ryegrass (Population O) had a level of resistance...

The first cases of weeds developing resistance to glyphosate within New Zealand have recently been reported and investigated. Both perennial ryegrass (Lolium perenne) and Italian ryegrass (Lolium multiflorum) populations have become resistant to glyphosate in several Marlborough vineyards due to many years of weed control using mainly just glyphosa...

This study examined if glyphosate-resistant populations of Lolium multiflorum and Lolium perenne from some New Zealand vineyards were still susceptible to glufosinate and amitrole. The response of plants of one glyphosate-resistant population of L. multiflorum, population A, and two glyphosate-resistant L. perenne populations, populations J and O,...

Background Perennial ryegrass (Lolium perenne) has developed resistance to glyphosate within New Zealand vineyards following many years of herbicide application. The objectives of this work were to confirm resistance within two populations obtained from affected vineyards and to determine the mechanism of resistance to glyphosate.ResultsPopulation...

In New Zealand vineyards, evolution of glyphosate resistance in perennial ryegrass (Lolium perenne) has been reported recently, and restricted translocation of glyphosate has been found in these resistant plants. Past research with other plant species has found that restricted glyphosate translocation is temperature dependent. Glasshouse dose-respo...

Three quick tests were evaluated for detecting glyphosate-resistant biotypes of Italian ryegrass and perennial ryegrass. Biotypes of these two species were used that were 13.4 and 7.3 times more resistant to glyphosate, respectively, than susceptible biotypes when assessed using a sprayed pot study. One assay exposed germinating seeds of resistant...

Research in the 1980s showed that Ranunculus acris had evolved resistance to the phenoxy herbicides MCPA and MCPB in New Zealand. Since then two ALS-inhibitor herbicides, flumetsulam and thifensulfuron-methyl, have been used but recently flumetsulam has been reported as being less effective. The mortality responses of seedling progeny of 15 R. acri...

Many of the herbicides used in site preparation of forests and during initial selective weed management can persist in the soil for several months, killing or stunting seedlings of broom (Cytisus scoparius (L.) Link) as they establish. The objective of this research was to determine the relative persistence and effect over time of the herbicides mo...

A quick test was developed using seeds in petri dishes to detect resistance to dicamba in fathen (Chenopodium album L.) which has developed in some maize fields in Waikato, New Zealand. Seeds were collected from four Waikato maize fields (populations A, B, L and M) where dicamba has been applied for many years, and also three sites (populations C,...

Herbicide treatments were assessed in two concurrent experiments for improving the establishment of manuka seedlings (three provenances) transplanted into hillside pastures for honey production. Height and trunk diameters 18 months after planting were still significantly reduced by initial poor control of weeds. Controlling weeds in a patch of 1.0...

A dose-response experiment was conducted on a previously confirmed glyphosate resistant perennial ryegrass (Lolium perenne) population from a Marlborough vineyard to examine if it is also resistant to amitrole after an initial experiment suggested amitrole is less effective on this population. The plants of two populations of perennial ryegrass, Po...

Some organic farming literature suggests that the presence of weeds in pastures can be explained by problems with the soil. Sixty 1 m2 patches of pasture with different densities of broad-leaved dock (Rumex obtusifolius) were identified across six different paddocks on an organic dairy farm. Various soil parameters were measured in each patch to de...

To investigate rumours that herbicide resistance has developed in wild oats (Avena fatua) seeds of this species were collected from eight arable farms (either one or two populations per farm) in Canterbury from which possible resistance to either fenoxapropPethyl or haloxyfop had been reported Seeds were also obtained from two properties where no r...

A doseresponse experiment was conducted on a previously confirmed glyphosate resistant perennial ryegrass (Lolium perenne) population from a Marlborough vineyard to examine if it is also resistant to amitrole after an initial experiment suggested amitrole is less effective on this population The plants of two populations of perennial ryegrass Popul...

To assist with managing the outbreak of resistance to dicamba that has developed within fathen (Chenopodium album L.) in New Zealand maize fields, a quick test has been developed using seeds. As dormancy of the seeds initially hindered development of a quick test, experiments showed that this can be overcome by removing the perianth from each seed,...

Plants were obtained from two populations of Italian ryegrass (Lolium multiflorum) and three populations of perennial ryegrass (Lolium perenne) from different vineyards in Marlborough and Nelson that were suspected of being resistant to glyphosate following many consecutive applications of this herbicide over recent years. Each population was multi...

A trial was conducted on an organic dairy farm in Manawatu, New Zealand, to determine how well perennial weeds are controlled during pasture renewal. Changes in weed populations were monitored following three different non-chemical methods of regrassing. Regrassing by planting pasture 4 weeks after ploughing the old pasture ("grassto- grass") was c...

A ield trial was conducted in Palmerston North to compare autumn applications of several translocated herbicides for great bindweed (Calystegia silvatica) control in riparian zones. Regrowth in the following spring showed that a triclopyr/picloram/ aminopyralid mixture, a 2,4-D/dicamba mixture and aminopyralid by itself were the three most effectiv...

A field trial was conducted in Palmerston North to assess weed control options for establishing mixed swards of chicory (Cichorium intybus), narrow-leaved plantain (Plantago lanceolata), red clover (Trifolium pratense) and white clover (Trifolium repens), a pasture mixture currently popular for finishing lambs. Haloxyfop safely controlled grass wee...

A pot trial and two field trials evaluate the safety to stevia plants of 25 herbicides, many of which have been used for selective control in other Asteraceae crops. Pre-emergence herbicides that show potential for use in transplanted stevia include trifluralin, pendimethalin, oryzalin, bromacil, terbacil, linuron, methabenzthiazuron and alachlor....

Twelve ornamental ground cover species were planted then monitored for 2 years to assess their relative usefulness for controlling weeds. Persicaria capitatum established quickly and covered the plots, but it was unsuitable for keeping weeds controlled because it died back each winter from frost damage. Acaena inermis and Muehlenbeckia axillaris al...

The herbicides flumetsulam, thifensulfuron-methyl and MCPA were compared for their efficacy against giant buttercup (Ranunculus acris subsp. acris L.) and their damage to perennial ryegrass (Lolium perenne) and white clover (Trifolium repens). The tolerance of perennial ryegrass and white clover to five rates of each herbicide was measured using sw...

Seeds of eight plant species were fed to four penned goats on three separate occasions. The faeces were collected over subsequent days, then seeds were recovered and tested for viability. Less than 10% of the ingested seeds survived passage through the goats for five of the species, though 32.3% of broad-leaved dock (Rumex obtusifolius) seeds and 1...

Broom (Cytisus scoparius (L.) Link) is an invasive weed in many commercial radiata pine (Pinus radiata D.Don) plantations throughout New Zealand. As broom competes strongly with newly planted pine seedlings and has an abundant seed bank that persists longer than the forest rotation cycle, ongoing broom control is essential to prevent significant lo...

A bioassay tested how long after application that residual herbicides used in forestry continue to suppress or kill broom (Cytisus scoparius) seedlings. Eleven herbicide treatments were applied to small plots of Tokomaru silt loam soil near Palmerston North on 4 December 2008. Soil samples were taken fortnightly until herbicide residues no longer a...

Weed control strategies for establishing three ground cover species were investigated by planting them in late spring, then assessing eight different control treatments during the following 14 months. The prostrate woody Coprosma acerosa 'Taiko' established best with black weed mat mulch and EcoCover paper mulch, although bark mulches also gave rea...

A bioassay tested how long after application that residual herbicides used in forestry continue to suppress or kill broom (Cytisus scoparius) seedlings Eleven herbicide treatments were applied to small plots of Tokomaru silt loam soil near Palmerston North on 4 December 2008 Soil samples were taken fortnightly until herbicide residues no longer aff...

A range of herbicide treatments was applied to 0.5 m2 zones around native plants, 6 weeks after being transplanted into ungrazed pasture for revegetation purposes. The species studied were toetoe (Cortaderia fulvida), mountain flax (Phormium cookianum), purei (Carex secta), ribbonwood (Plagianthus regius), koromiko (Hebe stricta) and manuka (Leptos...

New Zealand's primary production relies on pesticides to protect crops against diseases, invertebrate pests and weeds so that our agricultural systems continue to be competitive in world markets. Unfortunately, the repeated use of some pesticides can lead to the development of resistance in some pest species. Pests here include fungi and bacteria (...

To determine how rapidly ornamental ground cover species can establish and thus potentially stop weeds from establishing 12 perennial species with different growth forms and habits were planted into plots covered with 7 cm of sawdust mulch Plants had a mean diameter varying from 10 cm to 41 cm when transplanted in November 2008 with 10 m spacing wi...

Most comparisons between organic and conventional dairying available in the literature are from Europe or North America where the conventional systems are more intensive than conventional systems in New Zealand. This paper compares the cost of production and profitability of certified organic and conventional dairy farming over five years of a Mass...

One half of a Massey University dairy farm was converted to an organic production system in 2001 and the other half continued to be fanned as a conventional unit. Aspects of these two systems have been compared over the subsequent years, including the weed flora measured twice a year since 2003 along set transects within each system. Overall there...

Weed wipers available in New Zealand vary in their mechanisms for delivering herbicide The objective of this experiment was to measure clopyralid output from three weed wipers using a standardised methodology The herbicide output for the Eliminator Rotowiper and Weedswiper was investigated at different speeds of application The herbicide was applie...

During the establishment of native plants in revegetation projects, the plants often need to be released from weed competition, but little is known of their tolerance of herbicides suitable for release spraying. Ten native species were treated as 8-month-old plants in planter bags with eight herbicides at rates suitable to control weeds. Clopyralid...

Biotypes of nodding thistle (Carduus nutans) have developed within New Zealand that require over six times the normal rate of MCPA, MCPB or 2,4‐D to kill them. Radiolabelled 2,4‐D was applied to both resistant and susceptible nodding thistle plants to investigate the mechanism of resistance. There was no difference in penetration of the 2,4‐D into...

Organic dairy farmers often introduce alternative pasture species such as chicory (Cichorium intybus) and narrowleaved plantain (Plantago lanceolata) to their swards because of their higher mineral contents yet they are concerned about the presence of weed species such as docks (Rumex spp) and dandelion (Taraxacum officinale) The mineral content an...

Grass and broad-leaved weeds can reduce both yields and product marketability of desmanthus (Desmanthus virgatus) seed crops, even when cultural control strategies are used. Selective herbicides might economically control these weeds, but, prior to this study, the few herbicides tolerated by desmanthus did not control key weed contaminants of desma...

Madeira vine is an environmental weed with both aerial and subterranean tubers and is listed as a Surveillance Plant Pest by ManawatuWanganui Regional Council A field trial showed mature vines and their attached tubers were best controlled using metsulfuronmethyl although reasonable control was also provided by a triclopyr/picloram mixture and by g...

A trial was established in a new Hawkes Bay apple orchard in September 1998 to determine how well various ground cover treatments could control weed competition and influence tree production Results are presented after six growing seasons Competition during the first growing season resulted in effects on the trees that were still measurable many ye...

A commercially available paper mulch (EcoCover) was assessed for its persistence under field conditions and its ability to control weeds in vegetable crops and establishing trees. Weeds were controlled as effectively by EcoCover in autumn-planted cabbage and lettuce crops as by black polythene mulches. The paper mulch was beginning to break down by...

A field and an outdoor tray experiment were conducted to determine whether weed control benefits of high sowing rates of perennial ryegrass (Lolium perenne) continue into the second year after sowing. Seeds of Scotch thistle (Cirsium vulgare), nodding thistle (Carduus nutans) and hedge mustard (Sisymbrium officinale) were sown into perennial ryegra...

A field trial evaluated several different techniques for establishing strips of dichondra (Dichondra micrantha) under newly planted apple trees for weed control purposes Each technique involved planting a line of dichondra either side of the tree row with lateral spread of the plants eventually allowing the two strips of ground cover to merge Plugs...

When black nightshade (Solanum nigrum) plants were poorly controlled by cyanazine in a Manawatu pea crop seeds were collected from these plants and susceptibility of the resulting seedlings to various herbicides was compared in pot experiments with other black nightshade plants The biotype was resistant to cyanazine terbuthylazine atrazine prometry...

The effect of the density of perennial ryegrass (Lolium perenne) swards on the emergence of ragwort (Senecio jacobaea) was investigated in the field and in trays Ragwort seeds were sown into established perennial ryegrass and white clover (Trifolium repens) swards and the seedlings were mapped at intervals to aid in identification of new seedlings...