According to the author of 2 Kings, the people were weak and confused, like grass that withers quickly in the hot sun. They didn't have the strength to stand against their enemies, just like young corn that dries up before it can grow.
2 Kings 19:26: Therefore their inhabitants were of small power, they were dismayed and confounded; they were [as] the grass of the field, and [as] the green herb, [as] the grass on the housetops, and [as corn] blasted before it be grown up. [of small...: Heb. short of hand]
This verse is a parallel account to 2 Kings 19:26 and doesn't contradict but instead confirms the same message, showing consistency rather than contradiction.
Isaiah 37:27: Therefore their inhabitants [were] of small power, they were dismayed and confounded: they were [as] the grass of the field, and [as] the green herb, [as] the grass on the housetops, and [as corn] blasted before it be grown up. [of small...: Heb. short of hand]