"Poisonville is ripe for the harvest."
These words are spoken by the Op, but he's not talking about farmers and the physical act of harvesting. The word "harvest" here is being used metaphorically to refer to the Op's diabolical plan to turn everyone against each other.
To really understand how the symbol of the harvest works here, let's first turn to good old dictionary and see specifically how the word is defined. So if we flip to the letter "H", the definition of the verb "to harvest" is:
- to gather in (a crop)
- to gather, catch, hunt, or kill (as salmon, oysters, or deer) for human use, sport, or population control
- to remove or extract (as living cells, tissues, or organs) from culture or from a living or recently deceased body especially for transplanting (source)
Okay, so if we look at the literal meaning of the word "harvest," then clearly the Op isn't saying that Poisonville has crops that are ready to be harvested or animals that need to be hunted. But if we combine these three definitions together and think of "harvesting" on a more symbolic level, then the image actually makes a lot of sense.
Let's recap: the Op wants to cleanse Personville (aka Poisonville) from its corrupt thugs. So his plan is to:
- "gather" them all together and turn them against one another,
- have them "kill" each other off, so that
- their corrupting influence will be "removed" from Personville.
Notice how the image of a "harvest" functions metaphorically in the same way as the word's literal meaning? Yeah, we thought that was pretty cool, too.
So how bout the first part of the title, why "red" harvest? Well, what does the color red make you think of? Roses and Valentine's day? The Philadelphia Phillies' baseball jerseys? Icky, gooey blood? If you said "blood," then you've just won a million dollars! Okay, not really, but you're still a winner.
Hammett uses the color red in the title Red Harvest to refer to the bloody corpses that accumulate over the course of the novel (refer to the "Symbols, Imagery and Allegory" section to read more about blood-related imagery). The Op's plan to purify Personville involves a lot of bloodshed, and a key question to think about here is whether "the ends justify the means." Is it morally acceptable that so many people have to die in order for Personville to be cleaned up?