Who killed the loquat?
 

I am in the process of establishing a mixed orchard near Stroud NSW. The
soil is clay silt and quite fertile on a gentle slope. Each tree has been
planted in a dug over plot about 1.5 m wide with added compost and gypsum
and mounded up to improve drainage. Each has been deep watered regularly
when it didn't rain. The basic pH is about 5.5 amended to about 6.5 with
lime for most except the acid-lovers. Nearly all (citrus, stone fruits,
apple, quince, mulberry, feijoa etc) are doing really well. The loquat's
leaves slowly turned brown and now it is dead.

My understanding is that the loquat prefers acid conditions which is why it
got no lime.

What killed it?

David