Pesticide Formulations, Selection and Compatibility
This domain tests formulation types, active-ingredient calculations, and compatibility. You need to know how an emulsifiable concentrate (EC), wettable powder (WP), suspension concentrate (SC), water-dispersible granule (WG), soluble liquid (SL), bait, and fumigant behave in the tank and on the target.
Core rules
- The label gives product rate; the active ingredient (a.i.) rate is product rate multiplied by the a.i. fraction. A 50% WP at 2 kg product/ha delivers 1.0 kg a.i./ha.
- Formulation affects mixing, nozzle choice, agitation, and crop safety. ECs mix easily but can damage sensitive foliage; WPs need good agitation and can abrade nozzles; SCs are liquid suspensions that need shaking.
- Compatibility can be physical (clogging, flocculation, separation) or chemical (loss of activity, crop injury). Do a jar test before tank-mixing unfamiliar products.
- Typical mixing order: half-fill with water, add WG/WP, then SC, then EC, then SL, then adjuvants, with agitation.
Worked example
A grower wants to tank-mix an EC insecticide with a WP fungicide. In a clear jar, add water at the field dilution, add the WP, mix, add the EC, and observe for 30 minutes. If flakes, oil film, or heat appear, do not mix. The reasoning is that the jar test is a small, cheap proxy for the tank; a failed test avoids a spoiled 200 L load and possible crop burn.
Traps
Confusing product rate with a.i. rate; adding EC before WP; assuming two products with different names have different modes of action; and skipping agitation for WPs.