Wandering Jew (Tradescantia fluminensis) prevents the regeneration of native forests in New Zealand The herbicide triclopyr effectively controls this weed but is damaging to many native plant species To identify alternative herbicides 16 active ingredients representing eight chemical groups were applied to containergrown wandering Jew plants of various ages in three experiments In Experiment 1 triclopyr killed all plants (3 months old) while amitrole caused substantial damage to plants In Experiment 2 amitrole terbuthylazine metsulfuronmethyl and triclopyr provided excellent control of 2 month old plants In Experiment 3 on 4 monthold plants wandering Jew was highly susceptible to triclopyr metsulfuronmethyl fluroxypyr glyphosate fluroxypyr metsulfuronmethyl triclopyr and picloram triclopyr These herbicides were evaluated in a subsequent field trial and all except metsulfuronmethyl gave similar levels of control to Experiment 3 Further investigation of these chemicals is required to determine their optimal use rates and safety for native plants

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Wandering Jew (Tradescantia fluminensis Vell) is a common weed in canopydepleted indigenous forest remnants in New Zealand In this study triclopyr was applied to dense stands of wandering Jew at a range of rates in each of two experiments (Diamond Harbour in the South Island and Te Pahu in the North Island) to determine its effects on the weed and subsequent regrowth The cover of wandering Jew was initially reduced by 80100 with herbicide application At about 1 year after application of the herbicide the wandering Jew had regrown to about 350 cover depending on the rate of triclopyr applied and some indigenous seedlings had begun to appear However the survival of these seedlings was minimal

This study aimed to determine the effects of different management practices for Tradescantia fluminensis in lowland podocarp/broadleaf forest remnants in the lower North Island Fourteen 50 m line transects across eight sites were established in April 2009 and assessed annually until 2012 Management practices prior to and during the study period were documented Over the four assessments changes in the numbers of native plant seedlings and species differed greatly between management practices as did the percent cover of Tradescantia and other weeds Native species diversity improved more and the abundance of Tradescantia and other weeds increased less in forests that were less disturbed and where careful ongoing control was carried out than in forests with more disturbance prior to or during control operations Effective monitoring of both weeds and native plants is essential to enable the outcome of weed management practices to be measured

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. acris populations, differing in historical exposure to phenoxy and ALS-inhibitor herbicides, were compared using a log-series of five doses of MCPA, flumetsulam and thifensulfuron-methyl. The resulting mortalities were higher than expected at lower doses, meaning LD 50 values were not reliably estimated. In a second experiment, the responses of one population with no previous exposure to herbicides and one population with high exposure to flumetsulam were compared using a wider range of doses of flumetsulam (0.04 to 25 times). The LD 50 values differed 5.3-fold between the resistant and susceptible biotypes. In a third experiment, four populations varying in past exposure to both herbicide groups were treated with either flumetsulam or MCPA. Resulting LD 50 values were higher in populations with high previous exposure to both groups. These results confirm that resistance to both phenoxy and ALS herbicides can occur in R. acris populations through repeated use. Since these are the only two available groups for the selective control of this weed in dairy pastures in New Zealand, the options for control are reduced.