The term chlorosis in plants refers to the lack of the green pigmentation chlorophyll which appears as yellowing of the plant tissue. The location of chlorosis in leaves and the symptoms produced can be a general guide in diagnosing plant nutrient deficiencies.
Nitrogen (N) deficiency in roses
Main symptoms
Leaves appear pale green through to general chlorosis, more pronounced in older leaves.
Lower leaves appear scorched and show dominant orange pigments.
The element nitrogen is readily mobile within the plant. The symptoms of nitrogen deficiency are related to its function in the plant, i.e. for chlorophyll formation and protein for cell growth. As sulphur is also an important part of protein, sulphur and nitrogen may show similar deficiency symptoms. Nitrogen deficiency occurs in older leaves, while sulphur deficiencies appear first in the new growth.
Solutions for nitrogen deficiency in roses
First check the pH. If it is too high (above 8) or too low (below 5) it will affect the availability of nitrogen.
Apply nitrogen fertiliser. A liquid fertiliser will give the quickest uptake. A slow release fertiliser will provide a steady release.
Ammonium sulphate, Urea and IBDU will give the quickest release. Check the container for nutrient content and application rates.
Iron (Fe) deficiency in roses
Main symptoms
Usually general chlorosis.
Whitening of the young leaves with veins remaining thin and green.
The element iron is not mobile in the plant and therefore deficiency symptoms appear in the younger leaves. Iron is essential for chlorophyll formation even though it is not a part of the chlorophyll.
Solutions for iron deficiency in roses
Check the pH of the soil. Iron will not be available to the plant at high pH (7.5 and above). If you have to plant in this type of alkaline soil, you will need to consider using foliar applications of Ferrous sulphate.
For roses growing in soils with an average or slightly acidic pH an application of Ferrous sulphate or iron chelates to the soil can be used.
Manganese (Mn) deficiency in roses
Main symptoms
Starts with interveinal chlorosis of young leaves.
Next, necrotic tissue may drop out giving the leaf a ragged appearance.
The element manganese is not mobile in the plant and deficiency symptoms appear on the young leaves. Manganese plays an important role in chlorophyll production and carbohydrate and nitrogen metabolism.
Solutions for manganese deficiency in roses
Check the pH of the soil. Manganese becomes less available in alkaline soils.
Apply a mixture of trace elements. Follow the application rates on the container.
Magnesium (Mg) deficiency in roses
Main symptoms
Interveinal chlorosis appears in older leaves, i.e. the veins remain green while the interveinal areas become chlorotic.
The only green area remaining is at the leaf tip or a V-shape near the base.
Magnesium is very mobile in the plant and can be transferred from the older to the younger tissues. Magnesium is part of the chlorophyll formation and it plays an important role of converting sunlight into usable energy.
Solutions for magnesium deficiency in roses
Check the pH of the soil. Magnesium does not become available at lower than 6.5.
Apply magnesium sulphate (epsom salt).
Editor's note
Lessons to learn:
Always check the pH of your soil before you plant your roses. Some soils with extremes of the pH range are not suitable for growing roses.
Check the leaf symptoms against the photographs in this article to help diagnose the problem.
Apply fertilisers to correct the problem.
Soil and leaf tissues can be sent to a laboratory for a complete nutrient status analysis.
Leaf yellowing on roses - Part 2: Chlorosis
Nitrogen (N) deficiency in roses
Iron (Fe) deficiency in roses
Manganese (Mn) deficiency in roses