Recognizing Mineral Deficiencies in Plants
Something looks off !
To the average person most nutritional deficiencies in plants are not easy to diagnose. They all tend to look the same to the untrained eye. You can tell there is something wrong but not exactly what. However, by focusing on the the pattern and color differences between the veins and interveinal tissue you can learn to diagnose them quite easily.
What's wrong !
Main Causes
Nutrient deficiencies of Nitrogen, Iron, Sulfur, and Magnesium are the most common in containerized garden plants under automatic irrigation. This is because the water constantly washes the minerals away and out of the soil. Those grown in sand, stone, gravel, and soil less mixes fair even worse - not to mention those not fertilized often enough!
Plants in ground are less affected as the minerals do not have far to go!
Chlorosis
The most common way to identify a deficiency is simply by looking at the current color of green on the leaf to the expected color green (Perrier bottle vs, olive) for the species. The yellowing of otherwise normal green tissue is caused by chlorophyll destruction or failure to form it because of lack of nutrients. The pattern is classic green veins with yellowing interveinal tissue.
Chlorotic leaves
Uncommon patterns include irregular mottling, stippling (similar to spider mite damage), bleaching (loss of all color), marginal yellowing, and banding - or alternating stripes of yellow and green in pines.
Our entire Plant Specialists team is taught how to identify chlorosis, nutritional deficiencies and the methods to remedy or prevent the issue. We love our green plants green !
Testing the soil
The most common method to determine if the issue is nutrition is by testing a soil sample. In most cases it is sufficient to determine soil nutrition levels (TDS) and would be adequate to establish if there is a need to fertilize.
The soil acidity should also be tested to verify the issue is not from the wrong pH in the soil. This will also indicate which type of fertilizer to use.
Diagnosing
Lack of Nitrogen
In broadleaf plants Nitrogen specific deficiency shows up as reduced growth, reduced leaf size, generalized chlorosis of the older leaves, fewer leaflets in compound leaves. The pattern of green veins and yellow interveinal tissue is the most common feature.
Needled evergreen have shorter, yellower, and more closely grouped needles.
Nitrogen deficient chlorosis in older leaves with smaller new leaves
Lack of Iron
Iron specific deficiency is similar to Nitrogen, but affects mainly only new leaves. Its the old leaves that stay green while the newer ones are yellowish or pale. It could also be from the incorrect soil pH locking up the available iron or lack of the mineral itself in the soil.
Chlorosis in new leaves is from lack of Iron
Soil Acidity issues
This chlorosis is a result of low sulfur in the soil, which makes the soil alkaline. The iron is in the soil but unavailable to the plants.
Rhododendron with chlorosis due to high pH soil
Lack of Magnesium
Magnesium deficiency is related to soil leaching and high pH. You see it commonly in potted dogwood trees. The chlorosis pattern is reversed – green tissue with yellow veins.
Chlorosis in euonymus - Notice the yellow veins
Viruses
Many plants can get viruses. Roses, peony and hydrangea are the most common. Here the pattern is called “vein clearing” where the veins are totally absent of color and the interveinal tissue is green. It may sometimes also be caused by toxicity of pesticides or herbicides.
Vein clearing caused by a virus
Our Garden Care Teams are fully aware of these issues and keep a close eye on the leaf patterns in your garden!
PLANT SPECIALISTS
GREENING NEW YORK FOR OVER 52 YEARS !
Article written by our Staff Horticulturist, Peter B Morris, BSc, MSc, MBA
All photographs used with permission @SHUTTERSTOCK