Haggai has this oracle of Yahweh about their poor crops. When they were expecting 20 measures of a crop, they only got 10 measures. When they were expecting 50 measures for the wine vat, they only got 20. Thus, even when they had some crops in the fields, they were below expectations. Yahweh had struck them and all their products. Despite their hard labor, their crops were hit with blight, mildew, and hail. Why did this happen? They had not returned to Yahweh, pure and simple.
Amos has this oracle of Yahweh repeat the same theme, that despite the failure of their gardens and vineyards, they did not return to Yahweh. He had struck them with blight and mildew. Yahweh had laid waste their gardens and vineyards. Locusts devoured their fig trees and olive trees. Despite all this devastation, the Israelites of the northern kingdom did not return to Yahweh.