An indicator that plants have reached level three of plant health is when they begin expressing a glossy, waxy sheen on the leaf surface. This shine is a result of elevated lipid levels contributing to much thicker and stronger cell membranes. These strengthened cell walls enable plants to regulate water in the cells much more efficiently and greatly reduce transpiration, dramatically improving the plant's ability to withstand extended periods of dry weather.
Plants with high levels of lipids can produce high yielding and top quality crops with only a fraction of the water requirement of weaker crops, while seeming to ignore the drought conditions, where the same crop without the high lipids levels will be showing severe drought stress.
This waxy lipid layer on the leaf surface also contributes significantly to a plants resistance to airborne fungal and bacterial pathogens. When potential pathogens land on the leaf surface, they release a pectolytic enzyme, intended to degrade the pectins in the cell membrane allowing the pathogen to invade the cell, resulting in an active infection.
If we have a strong lipid membrane layer however, the pectolytic enzyme never gets access to the pectins, since the lipid layer serves as a shield, effectively preventing infection. When plants reach this level of plant health, they become largely resistant to the airborne fungal and bacterial pathogens such as fire blight, late blight, downy and powdery mildew, bacterial speck, bacterial spot, and bacterial canker, etc.