Technically Agent Orange is an equal mixture of 2,4,5-T and 2,4-D.
More importantly, it wasn’t the only thing the U.S. used in Vietnam. Agent Blue (civilian name: Phytar) for example, killed monocots. Also, the people doing the spraying weren’t that scrupulous about keeping the application rates at approved levels.
The idea was to defoliate the jungle, as Der Trihs says. That is to strip the leaves off the plants and trees in order to not only deprive the enemy of cover but to also reveal the pathways, trails, bunkers and other fortifications that were well hidden in the jungle.
The killing of food crops would have been a secondary consideration, if at all, because we were technically supportive of the general population, winning hearts and minds, and all that.
2,4-D is still widely used in the US. the product that I use goes by the brand name Crossbow and it is excellent at killing blackberry vines while leaving the underlying grasses alone. I do not know if 2,4,5-T killed everything, but 2,4-D leaves the grasses alone.
So I doubt if the intended role of Agent Orange was to deprive the enemy of food. You really could not do that without also depriving the friendlies of the same food.
I would have said the same thing before I clicked on kunilou’s link; the first sentence (bolding mine) is
I figured the Hitler Channel gets their facts wrong often enough, but checking wiki crop destruction was indeed also what it was deliberately used for:
ETA: There’s also a map showing defoliation vs anti-crop use.
Thanks for all replies. Sorry for not quoting the original sources, but I’ve read this many times (including in the Wikipedia entry for “Vietnam War”):
So destroying their crops is not thaaat much of a stretch really. And considering that more than 1M rural Vietnamese resettled to urban areas during the war, it all adds up.
But anyway my question was genuinely about crop physiology and not politics.