Citrus growers were cautioned to protect the fruit from frost.是什么意思？

Citrus growers were cautioned to protect the fruit from frost.

种柑橘者受到防霜保橘的劝告.

citrus

n. [植]柑橘属果树，柠檬，柑橘；

例句
...oranges, lemons and other citrus fruits.
橙子、柠檬和其他柑橘类水果

growers

n. 种植者( grower的名词复数 )，以某种方式生长的植物；

例句
Wine growers say they've been held hostage to the interests of the cereal and soybean farmers.
葡萄种植兼酿酒者说他们一直都为谷物和大豆种植者的利益所绑架。

were

be的过去时复数和第二人称单数形式，有时代替 was,用于条件从句、动词 wish 之后等；

例句
Shops, houses, and vehicles were set ablaze.
店铺、房子和车辆全都陷于火海。

cautioned

v. 警告，提醒，劝…小心( caution的过去式和过去分词 )；

例句
Tony cautioned against misrepresenting the situation...
托尼告诫说不要歪曲形势。

to

prep. 向，朝着，到，关于，属于；adv. 朝一个方向的，到某种状态，关闭；

例句
I suggest you leave it to an expert...
我建议你把它留给专家来解决。

protect

vt. 保护，保卫，贸易保护，备款以支付；

例句
It has been claimed that wine helps protect against heart disease.
有人声称葡萄酒有助于预防心脏病。

the

art. 指已提到的人（物），指说话人与听者已知的人（物），用于独一无二的事物前，与形容词最高级和序数词连用；

例句
He did have a real knowledge of the country...
他对该国的确知之甚多。

fruit

n. 成果，水果，果实，（大地的）产物；vi. 树或花草结果；vt. 使…结果实；

例句
...13 year-olds spending their pocket money on fruit machines in arcades.
将零花钱花在游戏机室中水果盘老虎机上的13岁的少年们

from

prep. （表示时间）从…，（表示原因）因为，（表示来源）来自…，（表示分离）与…分离[隔开]；

例句
...an abortive attempt to prevent the current President from taking office.
企图阻止现任总统连任的失败尝试

frost

vt.& vi. 使结冰霜，冻坏，（在蛋糕上）撒糖霜；vi. 结霜，受冻；n. 霜冻，结霜，严寒，寒冷，冷淡；

例句
There is frost on the ground and snow is forecast...
地上结霜了，而且预报说会有雪。