Bamboo

I have x2 yellow bamboo trees planted – they are down approx. x5 years and had been doing really well. Up until last year, they had grown to a height of approx. 10 – 12 ft tall, really full and green in summer but last Summer, they barely had any leaves at all. This happened to both trees and I worried that it was a hard frost that did the damage? If it was, I’m now worried that the recent harsh weather has really played havoc! Also, in the same bed I have x2 apple trees – last year there was no fruit at all on them but for the previous 4 years, were full of fruit?I saw your advice re mowing the lawn – ours could really do with a clip but if we have a hardy frost, will this not damage it?