求救! pls advise what's the problem with her (C45)

there is some red in the middle of the leave , is anyone can tell, what's the problem with her, thanks a lot........

呢啲好似係肥料鹽嚟架, 你可以用厠紙濕啲暖水"up"吓佢, 會好啲架

唔洗担心，肥傷嚟啫~   

Thank you Krista & Noel