The fig tree is a symbol of the Jewish nation, which had the outward appearance of fruits, because they had followed the letter of the law. But they lacked fruit in that they did not abide by the Spirit of the law and “neglected the weightier things of the law.” They continued to question His authority even to the last moment (9th hour gospel). Christ had rejected the Jews, as they were plotting to slaughter Him.
Truly, when He came and found no fruit in [the Jews], He cursed them through the fig-tree, saying, ‘Let there be henceforth no fruit from you;’ and the fig-tree was dead and fruitless so that even the disciples wondered when it withered away…The Lord cursed them under the figure of the fig-tree. And yet, you still He spared them in His loving-kindness, and did not destroy the root and the entire tree. For He did not curse the root, but [said] that no man will eat fruit of it thenceforth. When He did this, He abolished the shadow, causing it to wither; but preserved the root, so that we might [not] be grafted upon it; ‘they too, if they abide not in unbelief, may attain to be grafted into their own olive tree.’ Now when the Lord had cursed them because of their negligence, He removed from them the new moons, the true lamb, and that which is truly the Passover.
Letter 6, NPNF, s. 2, v. 4, p. 1245.