They are extremely hardy and drought tolerant. During recent autumns these trees, young and old, have suffered severe defoliation, sometimes to the point of apparent death. 

Miraculously, most have recovered only to suffer the same fate the next year. Each year the trees become weaker and eventually die. We have now lost close to half of them.

I have seen and heard firsthand that pepper trees are suffering the same symptoms throughout this region. Pepper trees are extremely sensitive to chemical drift.

Two mandarin trees have also died and our lemon tree is struggling. I wonder if what’s happening now is caused by chemical drift?

This defoliation of the pepper trees occurs at the same time the local cotton crop is being defoliated.

Cotton, a perennial bush, is killed to facilitate harvest.

Mature perennial plants are difficult to kill quickly. One of the main chemicals used to achieve this is Thidiazuron and the safety directions for using it include:

Do not allow spray drift to contact trees or crops other than cotton, as this product may injure or defoliate other crops … must not be sprayed up wind of citrus with young leaves within a distance of 8km.

Do not allow chemical to be sprayed on humans...

This is a potent, long-lasting chemical. If our pepper trees are being defoliated by this chemical, then citrus, grape vines and other plants in the same area.

Also, livestock over a wide area will be picking up traces of the chemical as they graze.

The gravest concern is that we are all unknowingly breathing this spray drift that is harmful to humans.