[thatmf]

You're conflating two different categories of product and their targets.

Copper is a fungicide, which is a category of product that both chemical ("conventional") and organic farmers often need to use for certain types of crops in certain types of climates, including pretty much any fruit. There are chemical fungicides which are more targeted and thus can be "greener" in some ways than copper, but there's also a lot more which are substantially worse.

Whereas RoundUp/glyphosate is an herbicide, which is a category of product that chemical farmers use extensively but organic farmers use rarely to not at all, relying instead on cultural and mechanical means. And what organic herbicides are used rely on contact rather than systemic action.

Funnily enough, both are pretty terrible when used near bodies of water. But chemical agriculture requires a much greater volume begetting much greater runoff.