Question
55 of my mautre peppercorn (Schinus areira = Schinus molle var. areira) trees were defoliated by a spray of 680 ester herbicide, they look dead to me, but the doer says they will recover. Any chance he is telling the truth, some are over 80 years old, it is the height of summer here (44 degrees C) and we have just had 25MM rain (post the spraying two weeks ago). If it were true when should they start to re grow and when do i give up and cut them down?

Answer
HI Jane,

It is often the case that when plants are treated with herbicides, the leaves drop fairly quickly, but they can regenerate from latent buds on the stems.

This particular herbicide uses plant hormone-like chemicals to stimulate respiration.  The plants essentially run out of "energy" due to the application of this herbicide.  Normally, overspraying in small amounts does little long-term damage.

The extent and duration of the damage depends on the concentration of the herbicide.  If this was an overspray (drifting onto your trees), then the chances are greater that the plants will recover completely.  If this was a direct spray (by accident,etc.), the chances are less.  In larger species of plants, such as trees or shrubs, it is likely that some parts of the plant receive less chemical than others, and the coverage may be spotty.

The quickness with which the plants regenerate leaves is very much determined by the environment; they will regenerate more slowly in dry, hot weather.  Give the plants sufficient time to bud new leaves....approximately two to three weeks.  By that time you should start to see new sprouts.  I would not do anything until approximately four weeks have passed.  Then if you do not see any leaves, examine the branches of the plant from the tip downward to the trunk.  Cut small pieces off the tip crosswise.  If you see a small greenish ring around the outside surrounding a creamy white center, then the tree is still conducting fluids from the roots, and is alive.  If you see none, then that part of the plant is dead. At this point, consult an arborist to determine the extent of the damage.


All the best.