。
The crops were badly damaged by the storm.
Literal
Storm [by-で] crops [subject-が] badly were-done-to.
やられる is the passive of the highly versatile やる — in this slang-ish sense, 'to take a beating / get wrecked.' ひどく is the adverbial form of ひどい ('terrible, severe'). Colloquial and evocative compared to a neutral 被害を受けた ('sustained damage').