Jar Testing For Compatibility

The jar test is the most practical way to determine the compatibility of a proposed product tank mix. We strongly suggest that a jar test be done prior to mixing FBSciences' products with non-FBSciences products. Sometimes pesticides may not mix well or a fluid fertilizer or liquid nitrogen may be the desired carrier. In addition, minor differences in the products can affect compatibility. Because of variance in pH, salt concentration or temperature, every batch of fluid fertilizer or liquid nitrogen should be tested for compatibility. Fungicides should never be mixed with fertilizers.

Materials Needed

• Two one-quart jars with lids, one marked with “agent,” one unmarked
• Teaspoons to measure out product
• Fluid fertilizer, liquid nitrogen or water that will be used as base
• The pesticides to be used
• A compatibility agent
• Consult table below to calculate the amount of pesticides to use for the test.

Pesticide Formulation            Rate/Acre        Teaspoons to Add
WP or DF                                           
                                                  1 lb                           1.5
                                                  2 lb                           3.0
                                                  3 lb                           4.5
                                                  4 lb                           6.0
EC, F, L, or S  
                                                  1 pt                           0.5
                                                  1 qt                           1.0
                                                  2 qt                           2.0
                                                  4 qt                           4.0

Conducting the Test

• Add 1 pint of the fluid fertilizer or liquid nitrogen to each quart jar. If the carrier is not a fluid fertilizer, add 1 pint of the water that will be used.
• To the jar marked “agent,” add ¼ teaspoon of compatibility agent. Shake gently.
• Add the proper amount of pesticides to each jar. Shake gently.
• Let the jars sit for 5 minutes. Check for any flakes, sludge, gel or other precipitants. Also look for any separation, layering or small oil particles.
• If incompatibility appears in the unmarked jar, but not in the jar labeled “agent,” use a compatibility agent.
• If incompatibility appears in the jar labeled “agent,” the product combination should not be used.
• If separate layers form after 30 minutes, but can be re-suspended by shaking, using sprayer agitation will make field application possible.

Problems to Watch For

The following signs indicate that an undesirable reaction has taken place and that this mixture is most likely incompatible:

• Gelling or thickening
• Flake or crystal formation
• Violent bubbling or heating
• Extreme color changes