Magnesium guide
Magnesium is a secondary nutrient at the centre of every chlorophyll molecule. The crop also needs it to make and use energy and to move...
Read the full guideMagnesium deficiency symptoms crop by crop
How magnesium deficiency looks in cotton, grapes, citrus, potato, banana, sugarcane and coconut, and how to tell it from potash and nitrogen shortage.
Magnesium shortage shows on the oldest leaves first: yellowing between green veins, often with red or purple tints, brittle leaves and early leaf drop. Cotton turns red during boll development, citrus shows a yellow wedge at the leaf base and banana a yellow band along the leaf edge.
By Gafar Laiya and the Gujarat Bio Organics team. Updated November 2026.
Crop by crop
| Crop | What you see |
|---|---|
| Cotton | Reddening of older leaves during boll development, early leaf drop. |
| Grapes | Yellow between veins of older leaves, poor berry colour and sweetness. |
| Citrus | A yellow wedge at the base of older leaves with a green tip, heavy leaf drop in fruiting years. |
| Potato | Yellowing between veins of lower leaves, brittle leaves. |
| Banana | Yellow band along the leaf edge of older leaves, purple mottling of leaf stalks. |
| Sugarcane | Small yellow spots on older leaves that turn brown and rusty. |
| Coconut | Yellowing of older fronds with a green centre, in leached soils. |
| Vegetables | Yellowing between veins of lower leaves, often during fruiting. |
How to tell it apart
| What you see on old leaves | Likely cause |
|---|---|
| Yellow between veins, veins green, reddish tints | Magnesium |
| Whole leaf pale, from the tip down the midrib | Nitrogen |
| Edges scorched and brown, centre green | Potassium |
| Young leaves yellow, old ones green | Iron or sulphur |
When to look
- During heavy fruiting and boll or tuber filling.
- After heavy potash doses.
- On sandy soils after heavy rain.
Confirm and correct
- Confirm with a soil or leaf test before you spend.
- Read the full magnesium guide for causes and correction.
- Use the symptom guide to compare with other nutrients.
Doses depend on the crop, soil and product, so this page gives methods, not amounts. Take the dose from your soil test report, the product label or your local agriculture officer or KVK. Results differ from farm to farm with soil, weather, crop and management. Farmer experiences on this site are their own reports, not a promise of results.
Read next
Potash, magnesium and calcium: the balance that decides leaf colour
How potassium, magnesium and calcium compete at the root, why heavy potash causes magnesium shortage, and when a calcium problem is really magnesium.
Read the full guideHow Gujarat Bio Organics can help
Since 2006, lakhs of farmers from Kashmir to Kanyakumari have used Immunity products on almost every crop: from the mango farms around Somnath to the apple orchards of Himachal Pradesh and Kashmir, the tea estates of Assam and Darjeeling, and the banana, coconut and cardamom farms of Tamil Nadu, Karnataka and Kerala. Each Special is one formula made for one crop and its common problems. Tell us your crop, soil test and what you see, and our team will tell you what to check, whether a micronutrient correction is needed, and which Special fits your programme.
- Cotton guide and Immunity Cotton Special
- Citrus guide and Immunity Citrus Special
- Potato guide and Immunity Potato Special
- Banana guide and Immunity Banana Special
- Sugarcane guide and Immunity Sugarcane Special
- Coconut guide and Immunity Coconut Special
Results differ from farm to farm with soil, weather, crop and management. Farmer experiences on this site are their own reports, not a promise of results.
Questions
What does magnesium deficiency look like in cotton?
Reddening of older leaves during boll development, early leaf drop.
What does magnesium deficiency look like in grapes?
Yellow between veins of older leaves, poor berry colour and sweetness.
What does magnesium deficiency look like in citrus?
A yellow wedge at the base of older leaves with a green tip, heavy leaf drop in fruiting years.