Photosynthesis can be inhibited by different stress factors in a variety of ways. Issues such as drought and nutrient deficiency starve the tree of raw materials required for photosynthetic processes to occur whilst stress caused by herbicide damage can physically break down the structures within the leaf itself.
Any of these factors can mean that the leaf is unable to photosynthesize at an optimum rate and the amount of light energy from the sun that the leaf is able to receive and process is reduced. Chlorophyll fluorescence is the method used by the leaf to dissipate the excess energy that cannot be used. Elevated stress on the tree means reduced photosynthetic activity and higher chlorophyll fluorescence emission.
For visual damage to occur, the leaf must go through a series of physiological processes starting with inhibition of photosynthesis and ultimately leading to leaf necrosis. This may take anything from a few days to several weeks depending on the type or combination of stress factors involved. Changes in chlorophyll fluorescence emission occur at the very start of this chain of events at the point where photosynthesis is inhibited. This allows Arborcheck to be highly effective in detecting stress and reduced vitality levels sometimes weeks before any visual symptoms are apparent.