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Plant & Food Research has developed the Botrytis Decision Support Model (BDSM) for vineyard management of botrytis bunch rot and has implemented it through this website in conjunction with New Zealand Winegrowers.

BDSM predicts risk of botrytis damage to wine grapes at harvest. It helps by providing information to support decisions on the need for botrytis management. Inputs include weather data from a nearby weather station and vineyard information from individual grape blocks. Outputs are graphs of botrytis risk from two separate models, the E-BDSM for the early-season (flowering to veraison) period and the L-BDSM for the late-season (veraison to harvest) period.

The risk summary helps support decisions on early season fungicide and biocontrol applications and canopy management. For the late-season, decisions on removal of botrytis-affected bunches during ripening and planning of harvest date to minimise botrytis damage are the focus. For multiple grape blocks the model prioritises high risk blocks for scheduling of spraying and harvesting. E-BDSM can also be used for retrospective analysis of last season's disease control programme performance.

E-BDSM uses weather information and management inputs to predict the risk that a major botrytis epidemic (≥3% botrytis severity at harvest) could occur. Because actual harvest severity depends on wet weather during ripening, which is unpredictable early in the season, E-BDSM cannot be relied on as the sole source of information for management decisions. Instead, E-BDSM can identify potential botrytis risk in a vineyard or region from early-season weather patterns and identify management actions that could bring botrytis risk down to an acceptable level.

L-BDSM does not rely as heavily on weather information, instead it uses measurements of botrytis severity and berry sugar concentration (°Brix) in the vineyard between veraison and harvest. From the date botrytis first appears L-BDSM predicts whether there will be a gradual or explosive increase in disease. It extrapolates the monitored rate of botrytis increase to predict harvest severity. °Brix monitoring is used to predict when harvest should occur using the Plant & Food Research °Brix prediction model incorporated into the L-BDSM.

These tools can help you to achieve:

  • Reduced seasonal variability in grape production and wine quality due to better management of botrytis.
  • Improved ability to manage fungicide residues while maintaining disease control.
  • Improved awareness of the effectiveness of various botrytis management options and how and when they should be applied.
  • Improved efficiency of botrytis control programmes, leading to reduced inputs in low risk situations.