Illinois Field Crop Applicators Practice Test

Volume Medium Diameter (VMD) describes what aspect of sprayer droplets?

1. Volume of liquid

2. Diameter where half the droplets are smaller and half are bigger

3. Mean weight of droplets

4. Velocity of droplets

The correct answer is: Diameter where half the droplets are smaller and half are bigger

Volume Medium Diameter (VMD) is specifically used to characterize the distribution of droplet sizes produced by a sprayer. It is defined as the diameter where 50% of the spray volume is contained within smaller droplets and 50% within larger droplets. This means that the VMD provides valuable information about the droplet size distribution, which is crucial for understanding how different droplets will behave in terms of drift, deposition, and coverage on the target. Understanding VMD helps applicators optimize their spraying techniques for different crops and conditions, ensuring effective pest or nutrient control while minimizing environmental impact. The other options do not accurately reflect the definition of VMD: the volume of liquid pertains to the total amount sprayed, the mean weight of droplets does not convey size distribution, and the velocity of droplets relates to their speed rather than their size.