Answer:
Drought and dust storms
Step-by-step explanation:
In the 1930s, these areas were covered with strong wind which carried out loose sand from the dry surface all the way to the agricultural fields. These sand prevented crops in these region to grow properly. As a result, many farmers experience failures in their harvests.
On top of that, these regions got very little rainfall during this time period. Causing a prolonged drought that prevented the farmers from properly providing the crops with enough water to survive.