New Zealand's pastures: Seed production and biocontrol of pests

Abstract

New Zealand’s pastures are dominated by perennial ryegrass (Lolium perenne L.) and white clover (Trifolium repens L.) with other grasses being minor contributors. The New Zealand seed industry produces pasture seeds on between 25,000-30,000 ha annually; in 2014 of the 50,600 tonnes of seed produced, 87% was ryegrass, 10% white clover and only 3% other species. Improved crop management has increased perennial ryegrass seed yield by 36kg-ha-year over the past 23 years, but for white clover the increase has been only 14kg-ha-year. New Zealand is currently importing seed, particularly of legumes, to meet demands for dry-land pastures. Pasture seed production is facing challenges, particularly competition from other uses for the land and the industry is working on strategies to mitigate these challenges. A feature of pasture seed is the association between the fungal endophytes Epichloë spp. and ryegrass and tall fescue. Novel Epichloë endophytes provide biocontrol of pasture pests without impacting animal health. Parasitoids have been successfully introduced to combat major weevil pests of legumes, while the biocontrol fungi Trichoderma spp. are showing promise for improved pasture performance in stress (diseases, drought) situations.