Magnesium Deficiency in Plants: Signs, Causes and How to Fix It
Magnesium deficiency in plants starts on the old, lower leaves. Magnesium sits at the center of every chlorophyll molecule, so leaves cannot stay green or make food without it. It switches on many enzymes, helps move phosphorus through the plant, and helps carry sugars to where they are needed. Here are the signs in each crop, what brings it, how to be sure and the fertilizer that fixes it.
Magnesium moves readily from lower to upper leaves when the supply runs short. So the yellowing between the veins starts on the old, lower leaves and reaches the young ones only in bad cases.
Magnesium deficiency symptoms
Older leaves turn yellow, orange or bronze between the veins while the veins stay green. So corn and rice leaves look striped or beaded. As it gets worse, the yellow parts turn reddish purple and die, and old leaves may drop early. Rice leaves grow wavy and droopy and fill fewer, lighter grains. Sweet potato leaves turn reddish purple.
Magnesium deficiency by crop
Each crop shows it its own way. So find yours in the tables below, then open its page for the photo and the full fix, like the one for magnesium in rice.
Rice
| Crop | The first sign | Fix with |
|---|---|---|
| Palay | Older leaves show orange yellow stripes between the veins, like a string of beads, and hang wavy. | Epsom salt / magnesium sulfate, Kieserite |
Corn and Sorghum
| Crop | The first sign | Fix with |
|---|---|---|
| Mais | Lower leaves get yellow to white stripes between the veins, later turning reddish purple. | Epsom salt / magnesium sulfate, Dolomite |
| Batad | Older leaves turn dark yellow between the veins, then deep red and rusty brown. | Epsom salt / magnesium sulfate, Dolomite |
Legumes
| Crop | The first sign | Fix with |
|---|---|---|
| Utaw | Older leaves turn yellow between the veins, then deep yellow with rusty specks. | Epsom salt / magnesium sulfate, Dolomite |
| Sitaw | Older leaves yellow between green veins, then deep yellow with rusty specks. | Epsom salt / magnesium sulfate, Dolomite |
| Paayap | Older leaves yellow between the veins, then deep yellow with rusty specks. | Epsom salt / magnesium sulfate, Dolomite |
| Kadyos | Mild yellow between dark green veins that turns rusty brown in streaks. | Epsom salt / magnesium sulfate, Urea 46 0 0 |
Root Crops
| Crop | The first sign | Fix with |
|---|---|---|
| Kamote | Older leaves yellow between the veins, sometimes with red or purple on top, and cup. | Epsom salt / magnesium sulfate, Dolomite |
| Kamoteng kahoy | Lower leaves turn yellow between green veins and cup inward. | Epsom salt / magnesium sulfate, Dolomite |
| Gabi | Older leaves yellow between dark green veins, then the edges brown and die. | Epsom salt / magnesium sulfate, Dolomite |
| Ubi | Light green crop with yellow between the veins of young mature leaves and light brown stains on old leaves. | Dolomite, Epsom salt / magnesium sulfate |
| Patatas | Mottled yellow between the veins of young mature leaves, then dead scorched patches. | Epsom salt / magnesium sulfate, Dolomite |
| Karot | Mature leaves yellow between green veins and drop, and roots are small and pale. | Epsom salt / magnesium sulfate, Dolomite |
| Labanos | Bottom leaves yellow between dark green veins, then redden and get dead spots. | Epsom salt / magnesium sulfate, Dolomite |
| Luya | Older leaves yellow between green veins with brown spots, sometimes with a yellow arrowhead at the leaf base. | Epsom salt / magnesium sulfate, Dolomite |
| Luyang dilaw | Older leaves yellow at the edges and between the veins, often with an arrowhead shape at the leaf base. | Epsom salt / magnesium sulfate, Dolomite |
Vegetables
| Crop | The first sign | Fix with |
|---|---|---|
| Petsay | Outer leaves yellow between the veins while the veins stay green. | Magnesium sulfate (Epsom salt), Dolomite |
| Repolyo | Outer leaves yellow between the veins and turn orange or red, while big veins stay green. | Magnesium sulfate (Epsom salt), Dolomite |
| Litsugas | Older leaves get yellow to orange edges and yellow between green veins. | Magnesium sulfate (Epsom salt), Dolomite |
| Kangkong | Older leaves yellow between the veins while the veins stay green. | Dolomite, Magnesium sulfate (Epsom salt) |
| Mustasa | Older leaves yellow between green veins, starting from the edge. | Magnesium sulfate (Epsom salt), Dolomite |
| Brokoli | Older leaves get a mottled yellow look between green veins, from the edges inward. | Magnesium sulfate (Epsom salt), Dolomite |
| Koliplor | Older leaves yellow from the edges toward the midrib while the veins stay green. | Magnesium sulfate (Epsom salt), Dolomite |
| Alugbati | Older leaves yellow between the veins, sometimes with a reddish purple tint. | Dolomite, Magnesium sulfate (Epsom salt) |
| Kintsay | Older leaves yellow between the veins while the veins stay green. | Magnesium sulfate (Epsom salt), Dolomite |
| Kamatis | Lower leaves turn yellow between green veins, starting from the leaf edge, while fruits are filling. | Magnesium sulfate (Epsom salt), Dolomite |
| Talong | Mature leaves turn yellow in the middle between green veins, with spotted dead patches. | Magnesium sulfate (Epsom salt), Dolomite |
| Ampalaya | Mature leaves yellow in the middle while the edges and veins stay green. | Dolomite, Magnesium sulfate (Epsom salt) |
| Kalabasa | Older leaves yellow between the veins, and the yellow patches die and fall out. | Magnesium sulfate (Epsom salt), Dolomite |
| Pipino | Older leaves yellow between the big veins, leaving a narrow green band along each vein. | Magnesium sulfate (Epsom salt), Dolomite |
| Okra | Fully grown leaves yellow in the middle while the edges stay green. | Magnesium sulfate (Epsom salt), Dolomite |
| Sili | Leaves that just reached full size turn yellow between the big green veins and drop early. | Magnesium sulfate (Epsom salt), Dolomite |
| Atsal | Older leaves go pale between the veins while a green band stays along each main vein. | Magnesium sulfate (Epsom salt), Dolomite |
| Patola | Oldest leaves yellow between the veins while fruits enlarge, and the yellow tissue falls out. | Magnesium sulfate (Epsom salt), Dolomite |
| Upo | Mature leaves yellow in the middle with green edges and green veins. | Magnesium sulfate (Epsom salt), Dolomite |
| Sayote | Oldest leaves yellow between the veins while the veins stay green. | Dolomite, Magnesium sulfate (Epsom salt) |
| Pakwan | Mature leaves yellow in the middle with green edges, and the yellow turns red and dies. | Magnesium sulfate (Epsom salt), Dolomite |
| Milon | Oldest leaves yellow between the veins while fruits are swelling, and the yellow patches fall out. | Magnesium sulfate (Epsom salt), Dolomite |
| Presa | Older leaf edges yellow and scorch, then the leaf turns bright yellow while its base stays green. | Magnesium sulfate (Epsom salt), Dolomite |
Onion and Garlic
| Crop | The first sign | Fix with |
|---|---|---|
| Sibuyas | Older leaves turn evenly yellow along their whole length, with white tips. | Epsom salt / magnesium sulfate, Dolomite |
| Sibuyas na mura | Older leaves turn evenly yellow along their length, with white tips. | Epsom salt / magnesium sulfate, Dolomite |
| Bawang | Older leaves yellow, with whitish tips, and bulbs grow slowly. | Epsom salt / magnesium sulfate, Dolomite |
| Sibuyas Tagalog | Older leaves turn evenly yellow with white tips. | Epsom salt / magnesium sulfate, Dolomite |
Sugarcane and Industrial Crops
| Crop | The first sign | Fix with |
|---|---|---|
| Tubo | Older leaves look rusty, covered with small orange brown freckles. | Magnesium sulfate (Epsom salt), Kieserite |
| Pinya | Older leaves turn yellow between the veins, most often where potash is applied heavily. | Kieserite, Magnesium sulfate (Epsom salt) |
| Tabako | Lower leaves yellow between the veins, starting near the tip and edge, while the top stays green. | Dolomite, Magnesium sulfate (Epsom salt) |
| Bulak | Lower leaves turn purple red between green veins, then drop early. | Magnesium sulfate (Epsom salt), Dolomite |
| Abaka | Old leaves yellow in the middle of the blade, edges stay green, leaf stalks show purple blotches. | Dolomite, Magnesium sulfate (Epsom salt) |
| Goma | Old leaves in the lower storeys yellow between the veins, the yellow moving in from the edge while the veins stay green. | Magnesium sulfate (Epsom salt), Kieserite |
| Palma | Old fronds turn bright orange yellow, but the shaded part of each leaflet stays green. | Kieserite, Magnesium sulfate (Epsom salt) |
| Kawayan | Older leaves get yellow streaks between green veins. Culms stay thin. | Dolomite, Magnesium sulfate (Epsom salt) |
Fruits and Plantation Crops
| Crop | The first sign | Fix with |
|---|---|---|
| Saging | Old leaves yellow in the middle of the blade while the edge stays green. Purple blotches on the leaf stalk. | Magnesium sulfate (Epsom salt), Kieserite |
| Papaya | Lower leaves yellow between the veins while green bands stay along the edge and the midrib. Leaf stalks look purple mottled. | Magnesium sulfate (Epsom salt), Kieserite |
| Mangga | Old leaves yellow between the veins while the veins stay dark green like a fishbone. Edges bronze. | Magnesium sulfate (Epsom salt), Kieserite |
| Niyog | Old fronds show a wide yellow band along the leaflet edges while the centre stays green. | Kieserite, Magnesium sulfate (Epsom salt) |
| Kalamansi | Old leaves near the fruit yellow from the sides inward, leaving a green V shape at the leaf base. | Dolomite, Magnesium sulfate (Epsom salt) |
| Citrus, dalandan or ponkan | Mature leaves next to the fruit yellow on both sides of the midrib, leaving a green V at the leaf base (bronzing). | Dolomite, Magnesium sulfate (Epsom salt) |
| Suha | Older and middle leaves yellow between the veins, leaving a green V at the leaf base, worst near the fruit. | Dolomite, Magnesium sulfate (Epsom salt) |
| Langka | Older leaves yellow between the side veins, from the edge in toward the midrib, while the veins stay green. | Magnesium sulfate (Epsom salt), Dolomite |
| Bayabas | Old leaves get yellow, bronze or reddish patches between the veins while the veins stay green. | Magnesium sulfate (Epsom salt), Dolomite |
| Rambutan | Older leaflets yellow between green veins. In bad cases lower leaves drop. | Dolomite, Magnesium sulfate (Epsom salt) |
| Duryan | Older leaves yellow between green veins. Lower leaves may drop. | Dolomite, Magnesium sulfate (Epsom salt) |
| Sapodilla | Older leaves turn greenish yellow between the veins while the midrib and big veins stay deep green. | Dolomite, Magnesium sulfate (Epsom salt) |
| Atis | Leaves yellow or greenish yellow between the veins while the leaf margins stay green. | Dolomite, Magnesium sulfate (Epsom salt) |
| Guyabano | A yellow to orange band along the midrib of older leaves while the leaf margins stay green. | Dolomite, Magnesium sulfate (Epsom salt) |
| Kaimito | Older leaves yellow between the veins while the veins stay green. | Dolomite, Magnesium sulfate (Epsom salt) |
| Saniata | Older stem segments turn yellow while the young shoots stay green. | Magnesium sulfate (Epsom salt), Dolomite |
| Kape | Old leaves yellow along the edges and between the veins, with a wide band of sunken light brown spots. | Magnesium sulfate (Epsom salt), Kieserite |
| Kakaw | Old leaves get tiny black pinpoints with yellow halos between the veins, then a marbled dead edge. | Dolomite, Magnesium sulfate (Epsom salt) |
What causes magnesium deficiency
Acid, sandy soils hold little magnesium, and heavy rain leaches it down past the roots. Heavy doses of potash or ammonium fertilizer crowd it out at the roots. So does liming with plain lime instead of dolomite. Rainfed and upland fields that never get magnesium back slowly run out, and surveys found magnesium short in some coconut areas.
How to be sure it is magnesium
Potassium shortage also starts on old leaves, but it burns the leaf edges instead of yellowing between the veins. Manganese shortage gives a similar pattern between the veins, but on the young leaves at the top. A soil test for exchangeable magnesium and pH at a DA Regional Soils Laboratory shows if the soil is short. A leaf tissue test confirms it, but take the same leaf at the same growth stage each time, because magnesium levels change with leaf age.
How to fix magnesium deficiency
On acid soils, dolomite is the cheapest fix, because it corrects the acidity and adds calcium and magnesium together. Where the pH is already right, or where heavy potash caused the shortage, use Epsom salt (magnesium sulfate) or kieserite. Let the soil test set the rate.
A magnesium nitrate spray at about 2 kg per 100 liters of water, every two weeks, is a typical rate in a Haifa vegetable guide. Magnesium sulfate (Epsom salt) also works as a foliar spray.
Fertilizers sold here that supply magnesium
| Product | Made or sold by | What it holds | Use |
|---|---|---|---|
| Dolomite | A6 Agrisource | 24 percent calcium and 11 percent magnesium | On the soil |
| Sc plus dolomite Foliar | Agway | 17 percent calcium and 10 percent magnesium | On the leaves |
| Lucky Planters Cal Mag 100 | Mindanao Agriplus | 20.7 percent calcium and 11.5 percent magnesium | On the soil |
| Agsmart Kieserite Granule | AgSmart | 20 percent sulfur and 16.3 percent magnesium | On the soil |
| DDDD Planter's Choice Magnesium Sulphate Monohydrate | Modern Time | 15.1 percent magnesium | Soil or leaves |
| Zetryl MAG 9 | Zetryl Chem | 9 percent magnesium | On the soil |
| Magnesium Nitrate | Unilox Far East Resources | 11 0 0 with 9.5 percent magnesium | Soil or leaves |
| Liquid Chelate Magnesium with Sulfur | Sagrex | 4 percent sulfur and 4 percent magnesium | On the leaves |
For rates and timing, see our guides to complete fertilizer and to fertilizer application methods. Also, anee.io keeps every application on the cropping calendar, so you know what went on each lot and when.
How to keep magnesium deficiency away
Lime acid fields with dolomite instead of plain lime, and keep potash in balance so it does not crowd out magnesium. Return straw and manure, and on sloping uplands control erosion so the topsoil and its magnesium stay put.
True magnesium excess is rare in farm soils. Research finds crops grow well over a wide range of calcium to magnesium ratios. So there is no need to buy products sold to fix the ratio when the soil test shows both are adequate.
Pick your crop in the Nutrient Deficiency Finder, say where the leaves changed first and what you see, and get the fertilizers sold here that fix it.
- Anee, the smart farm technician, reads a photo of the leaf in Tagalog or English
Magnesium deficiency questions
What does magnesium deficiency look like?
What is the best fertilizer for magnesium deficiency?
Can I spray Epsom salt on my plants?
Why did my crop turn yellow between the veins after I added a lot of potash?
Find the missing nutrient and fix it
With Libre + Anee, read the whole guide: how to tell the deficiency from look alikes, how to be sure, what to apply, and the fertilizers sold here that supply it.
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