Fungicides, applied by air with a heavy dew on the plant leaves.
Is really the only product that can be applied with a minuscule amount of carrier.
Without some real tangible performance reduction. 
This is only possible because the dew acts as part of the carrier.  
Applying contact Herbicide by air opens up the real possibility of serious drift issues. 
Many aerial applicators will not apply contact Herbicide’s for this reason.