Two exotic pests, Argentine stem weevil (ASW) and clover root weevil (CRW) are causing damage estimated at up to $200 M p.a. and $235 M p.a. respectively in dairy and sheep and beef pastures. While CRW is subject to successful biological control management it still causes considerable losses. Lesser pests also contribute to lost production, particularly as they often coexist with more major pests. However, their economic cost to New Zealand is difficult to calculate due to the variable nature of infestations on both temporal and spatial scales. At farm and paddock level, it is abundantly clear that substantial savings could be made if pest management is achieved. It is equally clear that in many instances the tools to do so are limited but if developed would contribute substantially to farm profitability.

A botanical survey of 24 commercial dairy pastures ranging in post-sowing age and perennial ryegrass type (mid-season diploid, late-season diploid, tetraploid) was undertaken in each of Waikato-Bay of Plenty (BoP), Taranaki and Canterbury during autumn/winter. The mean perennial ryegrass proportion (85% of total DM) and tiller density (3252 m −2 ) was greatest in Canterbury and the broadleaved weed proportion lowest (2%). Conversely, Waikato-BoP had the lowest ryegrass proportion (59%), tiller density (1817 m −2 ) and greatest proportion of broadleaved weeds (15%), with Taranaki intermediate. Tiller density was greater in pastures sown with diploid rather than tetraploids (averaging 3033 vs. 1784 m −2 ). Grass grub (Costelytra zealandica, 11 m −2 ) populations were lowest in the youngest age category pastures where nematode populations were highest (80 g −1 dry soil). The soil seedbank was dominated by unsown species (with total species emergence averaging 4594 seeds m −2 ), with negligible ryegrass emergence.

To determine the best method of pasture establishment on non-cultivable hill country (>20o slope), four treatments were compared in one year on north and south aspects at four sites with contrasting climates and soil types. Sites were located in Waikato (1), Hawke's Bay (2) and Canterbury (1). The treatments included seed mix (grasses, legumes and herbs (GLH); legumes only (LEG)) and sowing time (spring; autumn). Six weeks after sowing, seedling establishment, as a percentage of viable seeds sown, was: i) greater on south than north aspects for perennial ryegrass (31% vs 18%) and birdsfoot trefoil (5% vs 4%); ii) greater for total sown species (14% vs 8%), subterranean clover (7% vs 4%) and red clover (25% vs 14%) in the GLH than LEG mix, but greater for white clover in the LEG than GLH mix (17% vs 8%); iii) greater in autumn than spring for perennial ryegrass (36% vs 13%) and total sown grasses (22% vs 9%) but greater in spring than autumn for lotus (6% vs 3%). Plantain established well in spring in summer-wet environments, while in summer-dry environments establishment was greater in autumn. Broadcasting seed on south aspects during autumn is likely to result in the highest establishment of sown grasses and legumes, but not necessarily of herbs. The trials were conducted in an unusually wet season. Repeating a subset of the treatments at these sites will provide a greater understanding of responses to climatic variation. Keywords: pasture renewal; pasture establishment; pasture mixtures; oversowing.

To determine the impact of pasture renewal on dairy pasture performance, a total of 24 renewed and unrenewed pastures were monitored in Bay of Plenty and Waikato for 5 years. Renewed pastures produced an additional 1.5, 1.8 and 1.9 t dry matter (DM) ha −1 in the first, second and third years of monitoring, respectively, compared with unrenewed pastures. There was a greater contribution of clover, sown grasses and unsown grasses and a smaller contribution of broadleaf weeds in renewed than unrenewed pastures in some years (% of total DM). The sown grass DM content (kg DM ha −1 ), perennial ryegrass tiller densities and endophyte infection frequencies were similar in renewed and unrenewed pastures. The abundance of invertebrate pests and total nematodes was lower in renewed than unrenewed pastures in some years. The greater clover content, fewer weeds and fewer insect pests, contributed to the greater herbage production of renewed pastures.

An outbreak of the sporadic pest black beetle caused major damage on farms throughout Waikato and Bay of Plenty regions from 2007 to 2010. Two projects were initiated in these regions to gain an understanding of the interaction of black beetle with endophyte/ cultivar combinations and pasture renewal strategies. Monitoring of black beetle populations on the project farms showed that overall, abundance steadily declined from 2009 to 2013, possibly due to cool temperatures, and in the case of Bay of Plenty, high rainfall in 2010. In Waikato, pasture renewal in 2012 had no significant effect on beetle abundance in the following year compared to the unrenewed paddocks. Greater population levels in the Waikato sites were associated with lower soil pH. El Niño and La Niña weather events appear to be associated with changes in black beetle population levels, which may assist prediction of future outbreaks and damage risk. Keywords: Heteronychus arator, pasture, La Niña