By: Wendy McDonald – MPSG Production Agronomist – West
Growing up at Gladstone, when we were little, our favourite thing to do on a nice summer day was to go to Delta Beach! I think of Delta Beach to remember that Delta T, which tells you when the combination of air temperature and relative humidity add up to a nice summer day for successful spraying applications.
What is Delta T?
Another piece of useful information to help you make spray timing decisions.
Delta T (C)
Delta T is calculated from air temperature and relative humidity. It provides an indication of evaporation conditions and can be used in making spray decisions. Ideal Delta T is between 2 C and 8 C. High Delta T indicates dry air which may result in faster evaporation, while low Delta T indicates moist air and slower evaporation.
How I Find Out What My Delta T Number Is?
It’s useful to consult your Delta T number, as one of a number of factors to consider, to determine if now is the best time to spray fields or not.
I would first have a look at the Wind Speed and direction tab and the precipitation forecast.
Then I would look at Delta T value.
Luckily, Manitoba Agriculture has a Delta T function on their Current Weather Conditions page that is constantly updated.
Go to Province of Manitoba | agriculture – Current Weather Viewer Then under the Air Temperature tab, click the drop down menu, and select Delta T.
Red Dot? Not a Great Time for Spraying
Red means stop.
Yellow Dot? Not an Ideal Time for Spraying
Green Dot? Optimal Spraying Conditions
This first view shows you the whole province, but you can zoom in on your area, or click the dot closest to you to get all the information you need to make a spray timing decision.
Delta T at Drifting River weather station is marginal right at this moment.