Assuming the Associated Press interpreted the UN's comments correctly, the UN is attributing the worsening food shortages in Zimbabwe to the following reasons (WP):
The U.N. said this year’s food shortages are “worse” compared to the past three years due to drought, erratic rains and cash shortages to buy seed and fertilizers for impoverished farmers in the countryside, many who took over formerly white-owned farms.Except they buried the lede. The absolute absurdity of believing that all of a sudden weather is the result of some of the productive farmland in Africa becoming infertile might be plausible if it were not for the fact that they are unable to deny this aid is going to "impoverished farmers in the countryside, many who took over formerly white-owned farms" as if land appropriations were incidental.
With an organization that is unable to speak truth to power, advocating financial assistance to gloss over the political failures of a despotic government, why would anyone want to contribute more resources to their care? Or really, anything at all?