Llanerch
Observations
2025 comparison
2025 comparison
Temperature forecasts
OpenWeatherMap forecast
Corbeaucast
Forecasts vs observations
OpenWeatherMap forecast
Ecowitt weather station observation
CorbeauCast
Mildew advice
Powdery mildew and downy mildew are both important pathogens of grapevines and farmers typically spray sulphur and copper fungicides at 14 day intervals during the growing season. Conditions of high temperature and humidity encourage the growth and spread of mildews. CorbeauCast provides a daytime mildew risk indication of HIGH, MEDIUM and LOW. These correspond to vineyard conditions:
T>14 degC and RH >82%
T >14 degC and RH < 82%
T < 14 degC
At times of HIGH mildew risk, it is important to check the At Risk Hours number frequently because it can accelerate rapidly.
The At Risk Hours (ARH) chart provides a year-long record of accumulated mildew risk which can be considered when deciding on fungicide application. There are a number of potential intervention points:
75 hours – to tackle over-wintering spores
200 hours – to tackle mildew development
325 hours – to stop new mildew development
450 hours – to stop further mildew development and then every 125 hours if the season permits
Growing Degree Days advice
Growing Degree Days (GDD) is a useful record of how much energy a vine can potentially use to grow, flower, fruit and ripen. The GDD chart shows a cumulative total of GDD throughout the season.
It can be used to follow progress against expected phenological stages, alert to unexpectedly slow development and with a long-range weather forecast, to anticipate future stages.
Use the chart below to see how the vineyard or varietal parcels are progressing against expectations.
