The Question and Answer section for The Grapes of Wrath is a great resource to ask questions, find answers, and discuss the novel.
The farmers don't need the fruit because it's rotten. It can be used for wine but little else. The crops mentioned in this chapter are for the most part experimental.
Because of the Dust Bowl, the tenant farmers have no crops, thus, their land is worthless. With no income, no ability to pay, and a very questionable outlook for what's ahead, the land is sold, and the tenants are evicted.
What is Al Joad's attitude problem?