"You can add 1 teaspoon of liquid dishwashing detergent to each gallon of spray to help the herbicide stick to the leaves."

This is not optional if you want product to work. Some ester formulations of 2,4D may not need a spreader/sticker but most "off the shelf" products will be amine and a non ionic surfactant is a must to wet the foliage of garlic.

Baine