Dirtmechanic
Garden Addicted
For such small amounts of powerful borax or herbicide or other chemistry, taking advantage of dilution helps. For the 1/100 borax example, since 100 x 1/100= 1tsp, then a teaspoon in a 128oz gallon of water can be mixed and put on a shelf. When needed 1.28 oz ounces (38.3 mL) of premix can then be more easily and safely measured out into a gallon of water. Borax weighs 1.71 g per mL if you hear about or want to use a formula involving mass percentages like is used for fertilizer.It gets used in very heavy rainfall areas which are deficient in copper, very humid & have lots of anthracnose problems.
Else not usually the best option.
For Tomato leaf mold, Botrytis Cinerea, powdery mildew & bacterial leaf spot, (1/100) teaspoon of Borax in a gallon of water works better than Copper & is much safer.
(1/2) teaspoon of Citric acid per gallon of water is also responsibly effective & even safer than Borax.