“长霉”的英语可以翻译为：mildew ...

把面包扔了吧, 上面都长霉了.Throw the bread away, it have get mould on it.(使)长霉,(使)发霉受霉菌侵袭的或变成霉菌的.To affect or become affected with mildew.气候潮湿时,面包容易长霉.Bread tends to mould in damp weather....