Rashi: Lament. The Targum of Kinah (lamentation) is Iliya. Radak - this is said to Keneses Yisrael. They should lament this evil, and mourn greatly, like over a Besulah who married a bachelor, and he died while she was still a Na'arah. They had great Simchah with each other, and when he dies she mourns heavily over him.

Malbim: The Navi depicts that the vine and fig tree lament the matters said (verses 5-7). The vine tells the drunkards to cry, for 'a nation ascended on its land, and made its vine desolate.' They mourn like a widowed Besulah - this is a wondrous metaphor! The locusts ate and destroyed the branches of the vine and fig tree, and left only the stump.

Radak: She wears sackcloth in place of ornaments and necklace.

Malbim: The custom is to gird sackcloth on a stump whose bark was removed, to bandage and warm it, so it will sprout new branches. Chachamim call a sycamore tree that was never cut 'Besulas Shikmah' (Nidah 8b). The vine that was never cut is called Besulah and the branches cut from it are called Ba'al. She girds sackcloth over the Ba'al cut from her. The verse commands her to lament the lamentation above "Goy Alah Al Artzi" (6), i.e. on the land on which she grows, and destroyed her vine and fig tree.