They can handle pretty savage frosts. I've seen some healthy fruiting trees in parts of Canberra where snow is quite common. Which part of the tree are the yellowing leaves on?
I agree with Bruce...they take the frost very well.
Loquat's are used as ornamentals in South Africa, In my home town, Bethal...there were quite a lot of mature loquats and they handled the frost very well...no defoliation, what's so ever
jrgtwocreek,
Are the leaves getting yellow on top of the canopy or below?