However, soil test kits and pH paper are less expensive and more practical in the field. In general, the indicator is mixed with or dipped into the water and the resulting color is compared to a chart. It is often necessary to do a preliminary test with a wide range indicator included in the test kit to make a rough estimate. An indicator with a narrower range is then used for a more precise determination. Buffering agents are available to add to the tank water if the spray chemical is subject to alkaline degradation.
Chemical breakdown can take place quickly, before the tank is emptied.
If you are using a tank mix, it is important to know that susceptible materials should not be mixed with anything that raises the pH of the solution, such as lime sulfur and liquid ammonia. Also, fixed copper fungicides such as Bordeaux mixture should not be acidified. Copper is more soluble under acid conditions, and so if acidified, more copper will dissolve and could be phytotoxic. 118, Cornell University, Ithaca. Malathion is stable at pH 5.0-7.0 but rapidly hydrolyzes in more acidic or alkaline conditions.