No abstract

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

The impact of renewal on pasture production was determined by monitoring renewed and unrenewed pastures on five farms in each of Bay of Plenty and Waikato for 3 years, excluding the year after sowing (establishment). Renewed pastures produced an additional 1.5 t dry matter (DM)/ha averaged over both regions in the second year after establishment and 1.9 t DM/ha in each of the third and fourth years. Renewed pastures also had greater clover DM content in spring and summer and lower broadleaf weed DM content in winter. Perennial ryegrass tiller densities were similar in renewed and unrenewed pastures in both regions. There were fewer white-fringed weevil, black beetle and total nematodes in renewed pastures on at least one of the sampling times. It was concluded that higher clover content, fewer weeds, and fewer insect pests contributed to greater DM production in renewed pastures. Keywords: Pasture renewal; dairy pastures; pasture persistence; DM production; regrassing

It is common practice to renew old and "run-out" pastures that are not performing. Renewing pasture is costly so it is critical that the regrassing pays off. This trial on ten irrigated dairy farms from North Canterbury to North Otago was initiated to determine the value of regrassing on long term production and persistence of the new pastures. A pasture, deemed as run-out by the farmer, was subdivided and one half was renewed to a novel endophyte ryegrass pasture while the remainder of the paddock remained in the old pasture. The new pasture was compared with the original and another pasture on the same farm, considered by the farmer to be high performing. Pasture composition, production, and quality and pasture pests and endophyte infection have been monitored for two years. Herbage production is presented for the first 2 years of an ongoing trial, with quality and determination of wild/novel endophyte. When averaged across all 10 farms, the "control", "new" and "good" paddocks have all produced 15 t DM/ha in the year to May 2012. Levels of novel endophyte have remained high in the majority of new paddocks over the first 2 years. Clover root weevil is now present on all ten farms, at high levels (>200/m2) in some paddocks. Production from the new pastures equalled the total DM production from old pastures within 10 months of sowing. However, 2 years following pasture renewal, there has been no production advantage achieved from regrassing a stable old pasture. Keywords: pasture renewal, pasture persistence, irrigated dairy pastures, endophyte, pasture production, pasture composition

Constraints to pasture renewal success have been identified by many farmers so this multi-disciplinary study was initiated to trial and monitor the establishment, persistence and production of key forage species. Eight farms in the Bay of Plenty are being monitored. On each farm, paddocks have been selected so that a wide range of contrasting previous management and current pasture performance is covered. Keywords: clover, grass, dry matter, black beetle, clover root weevil, grass grub, white fringed weevil, cyst nematode, root-knot nematode, earthworm, soil moisture