Precision N application test costs 'outweigh returns'
Precision application of nitrogen can improve yields, but the costs of testing currently outweigh improved returns, according to new research from Plant and Food Research, MPI and Ravensdown.
Blouin, a senior staff member at Plant & Food Research Ltd in Auckland, is conducting a survey of grapevine viruses already present in the country as part of his studies at the University of Auckland. He also hopes that growers and viticulturists will contact him if they spot unusual symptoms in the vineyard during the period from late January to April.
Symptoms of interest include:
• Leaf distortion, leaf spots, leaf scorch or unusual leaf colouration (early yellowing or reddening, for example)
• Extremely low vigour
• Unusual branching or uneven wood maturation on canes
• Early leaf drop
• Graft incompatibility symptoms
‘The symptoms may be an indication of infection from one or more grapevine viruses, which can be identified using laboratory diagnostics,’ observes Blouin. ‘Some viruses might be harmless but the goal of my survey is to learn as much as possible about their presence and impact – and growers can help with that.’
Blouin is the current recipient of New Zealand Winegrowers’ Rod Bonfiglioli Scholarship, and he is working closely with team members from the Virus Elimination Project to stop the spread of Grapevine leafroll-associated virus 3 in New Zealand vineyards. He can be contacted by email at This email address is being protected from spambots. You need JavaScript enabled to view it.
