I have had over a period of about 3 years a number of perfectly healthy trees suddenly drop all their leaves and die. I suspect a caterpillar or some other insect pest has attacked the roots or stems.
A Number of Trees Mysteriously Died
Certified GKH Gardening Expert
What types of trees have died and what is the pattern of their death (yellowing leaves, defoliation, etc?) ? This will help us with determining what the pest may be.
I had two China Dolls (Canton Lace) and a Kowhai. The pattern was similar. With the China Dolls, the leaves turned yellow and would fall off the even if touched just slightly. The China Dolls leaves do go yellow and fall naturally as the tree grows but is this case there was no vigorous new growth taking place. Eventually, even the new growth turned yellow and dropped. At this point I decided to replace the trees. I pulled at the trunks and the trees came out of the ground without much effort. The root ball was almost non existant. In one of the trees I observed a caterpillar crawl from a hole in the stem. The Kowhai went virtually the same way. except no yellowing of the leaves before hand. The Kowhias do tend to lose about 80% of their leaves during winter anyway. But in this case the leaves did not grow back in spring. And the winter leaves all dropped away. When I removed this tree it too, came out with almost no effort and the root ball was again almost non existant. I have another Kowhai which seems to be going the same way. Last season it was very healthy had gave a glorious display of yellow flowers. But this spring there was a very poor display of flowers and the tree is almost bare of any folliage. The branches still have green sap, when cut it appears to still be alive there are still leaf buds which appear to be alive. When I shake the tree's trunk it appears to be loose in the ground. I suspect something is attacking the roots. I'm hopeful I can still save this tree.