Thank you for volunterring our grape downy mildew risk assessment model beta-test. This is our attempt to use a public weather data to forecast grape downy mildew risk events. It assesses night-time temperature and relative humidity to estimate spore production level. Then, it uses a 48-hour and 7-day forecast data to assess risk of infection.
What we would like to do is by running code, creating reports, and sending them as emails, we are hoping to find some potential bugs. We also need some help from you to refine the outputs and point out some potential bugs. Please feel free to contact me () for suggestions, concerns, etc.
Note: Weather information is based on OpenWeatherMap.org, and we do not have control over its accuracy. However, we would like to know the weather (history and forecast) makes sense to you. It has been OK (sometimes it is better than WeatherUnderground and not in the other time, etc.)

Location = AHS AREC, Winchester, VA

Downy mildew sporangiophore germination condition based on night time weather conditions (past 5 days)

When the night time temperature is warm and the average RH is high (more than 85%) for several hours, it triggers spore production.

Date Ave_T_Night () Max_T_Night () Min_T_Night () Ave_RH_Night (%) Condition
2023-08-18 23.3 26.4 20.7 74.9 not met.
2023-08-19 15.4 20.5 10.9 74.5 not met.
2023-08-20 15.4 19.6 12.6 84.1 not met.
2023-08-21 20.0 24.2 17.1 83.3 not met.
2023-08-22 23.4 26.1 21.7 82.3 not met.

Downy mildew infection risk based on a 48-hour weather forecast, which should be more accurate (We are working on the color scheme so that it will reflect the past germination risks.)

Time Ave_Temp () Max_Temp () Min_Temp () Rain_Hour Prob_Rain (%) Infection_Risk
~24h 20.4 29.0 12.8 0 0 not met.
25h~48h 22.0 30.3 15.6 2 57 low prob.

Forecasted downy mildew sporangiophore germination condition based on night time weather conditions in the 48 hours.

Time Ave_Temp_Night () Max_Temp_Night () Min_Temp_Night () Ave_RH_Night (%) Condition
~24h 15.4 21.1 12.8 57.3 not met.
25h~48h 18.2 22.8 15.6 64.7 not met.

Summary figure: 7-day downy mildew risk and weather conditions (note: it will be less precise compared with the 48-hour forecast). (We are working on coloring and shapes of the icons to make it easier to understand and being consistent.)

Downy mildew activities highly depend on the environmental condition, thus, please check the output daily (i.e., the infection risk may change based on what would happen in the coming/forecasted week.)

Date Description Ave_Temp () Prob_Rain (%) Amt_Rain (mm) Risk
2023-08-22 overcast clouds 26.7 0 0.00 not met.
2023-08-23 few clouds 28.8 2 0.00 not met.
2023-08-24 light rain 27.8 83 2.01 high prob.
2023-08-25 light rain 33.4 46 1.12 low prob.
2023-08-26 light rain 26.5 100 5.20 high prob.
2023-08-27 broken clouds 24.2 56 0.00 low prob.
2023-08-28 moderate rain 18.2 100 11.94 high prob.
2023-08-29 broken clouds 30.0 0 0.00 not met.

Fungicide and insecticide spray windows: Next 48 hours

This is based on the condition when the probability of precipitation is less than 60% and the wind scale is less than equal to 2. If you are spraying herbicides, please avoid when the wind scale is 0 (= no wind) to reduce risk of spray drift.