The region has received heavy rain fall this week – which have been close to producing a 10:10:24 Downy Mildew event. Fortunately night-time minimum temperatures have been below 10oC which slows the disease from starting its life cycle.
We feel there is only a low chance of Downy Mildew because vines do not have a sufficient canopy to host the disease.
A no risk strategy would be to protect your vineyard with your next scheduled spray round using a registered Downy Mildew protectant fungicide. Applied before further rain this protected against the spread of Downy Mildew, which could occur if we have future;
1- (10:10:24) Primary Events or,
2- Secondary events (warm, wet nights - 98% Relative Humidity with some rain before dawn).
Downy Mildew needs unprotected foliage to infect vines. We are entering the high-risk period when shoots are 10-30 cm long in the lead up to flowering. Leaves of any size are susceptible to infection but the larger the amount of unprotected foliage, the higher the risk.