Israel is left unprotected when she forgets the God who is her true Refuge. Isaiah explains this with more agricultural imagery. Israel would be like one who sows plants of pleasantness but harvests something else entirely. Labour expended on vanity will not yield the intended results. The day of inheritance will be oppressive and filled with sorrow.
10 For you have forgotten the God of your salvation and have not remembered the Rock of your refuge; therefore, though you plant pleasant plants and sow the vine-branch of a stranger,