Local farmers couldn't compete with the low price of subsidised rice being "dumped" from the US, so local production fell. When the cost of US rice eventually went up, Haitian people could no longer afford it, but there was no alternative.
In fact, 50 years ago, Haiti was completely self-sufficient in food; now, Haiti produces about 40%. We could become self-sufficient again and break the dependence on food aid. But it will take a combination of protective tariffs to prevent dumping, as well as a sustained investment in agriculture.