What is Delta-T?
Delta-T is the industry standard for monitoring evaporation potential.
Technically, it represents the difference between Dry Bulb temperature and Wet Bulb temperature. In the field, it tells you if your spray will evaporate before it hits the leaf or if it will wash off due to high humidity.
Delta-T suitability.
Cropspy gives a table for suitability of Delta-Tbased on use of Fungicides, Insecticides, Fertilizers and PGRs. Red color means it is not suitable for spraying, while Organce color means spray only in emergency situations, and Green color dot means ideal for spraying.
Low Delta-T (< 2)
High humidity. Droplets don't dry, leading to pesticide run-off and potential water contamination.
Ideal (4 – 8)
The "Sweet Spot." Perfect balance for droplet survival and leaf penetration.
In rare cases and with coarse particle spray Delta T between 8 to 10 can also be followed.
High Delta-T (> 12)
Hot & Dry. Droplets evaporate instantly (Flash Evaporation), wasting your chemical.
How to Use CropSpy Forecasts
15-Day Planning
Use the Daily Delta-T chart to identify which days in the coming week offer the largest windows of safety. This helps in scheduling labor and chemical deliveries.
Hourly Precision
Once you've picked a day, use the Hourly chart to find the exact start time. Often, the Delta-T is perfect at 6:00 AM but may become dangerous by 10:00 AM.
