HOW TO DO A SCRATCH TEST TO TEST FOR VIABILITY
It's sometimes hard to know if a plant has passed.

A plant is DEAD when it no longer possesses the ability to produce new growth.
There are many reasons as to WHY this might be, but for the moment what we need to know is if the plant is dead, or simply ill and/or has been damaged.

When you suspect a plant is dead but are not sure, take the following test;

1. Scratch the bark (the “scratch test”) on the shoots of your trees or shrub with your thumb nail or a penknife. A stem with green under the bark is alive; a stem with brown under the bark is dead. Living shoots also tend to have smooth, firm bark, whereas dead or dying shoots tend to have flaking, peeling or wizened bark.
   
   
   The tissue beneath the bark is called the 'cambium', and as it acts similar to 'stem cells' in humans, if it is alive (green), the potential for the plant to produce new growth exists.  This layer of green is directly beneath the 'skin' of the bark, so you don't have to 'whittle' a notch.
    
2. Where the shoots are dead at the tips, repeat the test on thicker wood to see if that is also dead. Where most or all of the upper parts of a plant are brown under the bark, the plant is most likely dead.