1. Faculty of Agriculture and Life Sciences, Lincoln University; PO Box 85084 Lincoln 7647 Christchurch New Zealand
2. School of Agriculture, Food and Environment, The Royal Agricultural University; Cirencester, Gloucestershire GL7 6JS UK
3. Central Experimental Farm, Agriculture and Agri-Food Canada; Ottawa Ontario K1A OC6 Canada
4. Bio-Protection Research Centre, Lincoln University; PO Box 85084 Lincoln 7647 Christchurch New Zealand
5. AgResearch, Lincoln Science Centre; Private Bag 4749 Christchurch 8140 New Zealand