Pest and disease (19)
Botrytis is the major bunch rot affecting winegrapes in New Zealand.
Botrytis fungicide residues are persistent and detectable in wines.
Controlling Botrytis requires an integrated approach involving vigour control, canopy management, fungicide application and reduction in Botrytis inoculum.
Water sensitive papers (WSPs) are a superior method for assessing spray coverage. WSPs should be used to assess bunch coverage prior to key Botrytis fungicide applications mid-fl owering and pre-bunch closure. 10 WSPs are folded in half and pinned to shoots adjacent to bunches. A minimum of 70% of papers should show adequate coverage to achieve good Botrytis control.
The New Zealand grass grub beetle can cause sudden damage to vineyards in late spring, defoliating shoots and leaves.
Damage is often confined to vineyard edges, where beetles emerge from headlands or neighboring paddocks.
Populations usually peak 2-3 years after cultivation – often coinciding with the vulnerable first crop on a vineyard.
Petri disease can significantly limit the growth and productivity of young vines.
Initial infection is by air-borne spores that typically enter through stem or root wounds in young vines during their establishment phase in the vineyard.
Damaging symptoms develop most often in stressed, young vines.
Control strategies focus on growing healthy plants in stressfree conditions and on preventing infection of pruning or trimming wounds.
Key
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