Nature/Agricultural Imagery in Isaiah

Isa 1:29  For they shall be ashamed of the oaks which ye have desired, and ye shall be confounded for the gardens that ye have chosen.
Isa 1:30  For ye shall be as an oak whose leaf fadeth, and as a garden that hath no water.
Isa 1:31  And the strong shall be as tow, and the maker of it as a spark, and they shall both burn together, and none shall quench them.

And the strong shall be as tow
The tinder, and the spark
“The strong shall become tow, and his work a spark, and both shall burn together”—a vivid picture of the doom of transgressors, since the mighty man is made combustible, and his own act is that which kindles the flame.
(T. W. Chambers, D. D.)

The fire of judgment that consumes sinners does not need to come from without; sin carries within itself the fire of wrath. (F. Delitzsch.)

Isa 1:28  But rebels and sinners will be completely destroyed, and those who desert the LORD will be consumed. 

Isa 1:29  You will be ashamed of your idol worship in groves of sacred oaks. You will blush because you worshiped in gardens dedicated to idols. 

Isa 1:30  You will be like a great tree with withered leaves, like a garden without water. 

Isa 1:31  The strongest among you will disappear like straw; their evil deeds will be the spark that sets it on fire. They and their evil works will burn up together, and no one will be able to put out the fire. -NLT

4  The LORD will mediate between nations and will settle international disputes. They will hammer their swords into plowshares and their spears into pruning hooks. Nation will no longer fight against nation, nor train for war anymore. isaiah 2:4