"Their memory perishes from the earth." In order that Bildad may not appear to speak inconsistently after saying, "Their roots dry up beneath," he had added, "Their crops are ruined above." He then concludes with what he wanted to convey through such a sequel of expressions, that is, "Their memory perishes from the earth." In fact, it could happen that the ripening of the fruits occurred before the drying up of the roots, which takes place over a long period of time. "Their memory perishes from the earth." All the things that happen to the impious are described in general but also obliquely referred to Job, because he suffers these same things under the scourge of God.
Source: EXPOSITION ON THE BOOK OF JOB 18:17