Plant Stress Detection Filters

Plant leaves absorb primarily red and blue light to make food (photosynthesis), and reflect greater amounts of green light–hence the leaves are green! Plant leaves that are stressed due to drought, flood, ozone, excessive foot traffic, salt spray, acid rain, nutrient deficiencies, disease, pests, etc., are not as productive photosynthesizers, so reflect more red and blue light. Using a filter that blocks out the green light, healthy plants will be dark and stressed plant leaves will appear light.

These filters do not tell you why the plant is stressed; they just make it easier see stressed parts of plants. You need to look for clues to find the cause of the plant stress:

• Which species of plants are stressed?
• Is there a common direction the plants are stressed? (Adjacent to road may indicate damage by road salt spray; if only the ocean-side leaves are burned, this indicates salt spray damage during storms, etc.)
• Look for presence of pests, blights.
• Is there damage only in low lands or atop hills?

Dr. Barry Rock from the University of
New Hampshire wearing the paper version of
the plant stress detection glasses during
a teacher workshop.

Illustrations of How Plant Stress Detection Filters Work

• Green leaves
• Stressed leaves
• Purple filter
• Using purple filter with plants  

Make your own Plant Stress Detection Filter Device

Build a Filter Flag (very low cost)

Build Cardboard Filter Glasses using Template: pdf gif

Build a Filter Monocular using Plastic Film Canisters (low cost, durable, and flexible to use with other filters)

Buy Plant Stress Detection Glasses

Using Plant Stress Detection Filters with Digital Cameras

Additional web resources about Plant Stress Detection Filter