Certified applicator here. Needless to say, every exception has a reason, and was lobbied for by applicators, manufacturers, or common sense. Let's run through them.
- (1) applying a pesticide at any dosage, concentration, or frequency less than that specified on the labeling
- unless the labeling specifically prohibits deviation from the specified dosage, concentration, or frequency,
This is mainly about rinsate. When you're done spraying, you have a bunch of flushing out to do. The empty jugs or barrels need to be triple rinsed with agitation (fill-shake-dump 3x). The dregs of the premix tank have to go, and the tank rinsed out with clean water. The spray equipment needs to be purged (not least so the acidic or basic pesticide doesn't corrode it). This yields a lot of "contaminated" water which is simply water + the pesticide at a lower-than-normal concentration. This is called rinsate.
You also sometimes end up with "leftover mix" or "mistake mix"; like 200 gallons of pre-mixed {Roundup? 2,4-D?) that a non-certified predecessor left behind. I don't know what that is, so I'll dilute it enough that it's definitely below maximums.
So you have all this chemical that is highly diluted, of ??? dilution but well below maxima. Can't dump it on the ground. Can't dump it down the drain. My friend says "How do you dispose of old paint? Paint something you don't want, then throw it away." And that's exactly what you do: identify locations that are legal to spray the stuff, and spray it there. It's much weaker, of course.
This exception (1) is specifically to allow for this case.
Of course you know you need to run a full antibiotic treatment, or you'll just breed antibiotic-resistant bacteria. Some cases are like that, and the product labeling will tell you "don't under-use". That's what the "unless" is for. Presumably in that case they'll tell you what to do with the rinsate.
- (2) applying a pesticide against any target pest not specified on the labeling if the application is to the crop, animal, or site specified on the labeling,
- unless the Administrator has required that the labeling specifically state that the pesticide may be used only for the pests specified on the labeling after the Administrator has determined that the use of the pesticide against other pests would cause an unreasonable adverse effect on the environment,
The first part of this is for accidental or collateral damage: think about how civilians figure into the rules of war. You can't go "12 civilians, shoot them", but you can go "11 soldiers, 1 civilian, shoot them".
Suppose you're spraying 2,4-D on your yard, at a 1.5 lb/acre rate (max 3.0) to suppress broadleaf (dandelions). "Lawns" are a crop specified on the labeling. Controlling broadleaf there is a labeled use, and therefore legal. Your yard also has butterflies. This is where the exception (2) comes into play. Since "the application is to the crop, animal, or site specified on the labeling" (2,4-D on lawns to control broadleaf), then, when the local butterfly admirer accuses you of applying a pesticide against any target pest not specified on the labeling (2,4-D is definitely not labeled for butterflies), you have a defense.
The butterfly is the civilian you can't aim at, but it is not a war crime if you shoot at a soldier and hit a civilian by mistake.
If the collateral damage becomes serious, e.g. there are big issues with pollinators (e.g. honeybees) being injured by pesticide use in factory farming, then the "Unless" clause allows the EPA to intervene and cancel exception (2) on a case-by-case basis. A consumer product might be pulled, or a commercial product will mention this in the (lengthy, fold-out) labeling.
- (3) employing any method of application not prohibited by the labeling
- unless the labeling specifically states that the product may be applied only by the methods specified on the labeling,
That is to give you the versatility to apply as needed. Imagine you are a farmer. Most farm pesticides are sprayed from a land vehicle, and you use the highest concentration that is workable because water is heavy. But suppose you're far enough west that your cornfield is a circle and you use a rotary irrigator. You might mix the pesticide in with the irrigation water (at a dramatically lower concentration). This exception relieves the manufacturer of the obligation to cover every possible application method. But the factory is able to override this.
- (4) mixing a pesticide or pesticides with a fertilizer when such mixture is not prohibited by the labeling,
Simply a labor-saver: to allow you to apply pesticide and fertilizer in one pass, which most gardeners appreciate. It also empowers products like weed-and-feed.
- (5) any use of a pesticide in conformance with section 136c, 136p, or 136v of this title, or
- (6) any use of a pesticide in a manner that the Administrator determines to be consistent with the purposes of this subchapter.
These are statutory phrasing to enable other legislation or rulemaking.
After March 31, 1979, the term shall not include the use of a pesticide for agricultural or forestry purposes at a dilution less than label dosage unless before or after that date the Administrator issues a regulation or advisory opinion consistent with the study provided for in section 27(b) of the Federal Pesticide Act of 1978, which regulation or advisory opinion specifically requires the use of definite amounts of dilution.
This locks in the "right to over-dilute" (exception 1) for ag and forestry applications.
