Melon Nutrient Deficiency: Signs, Causes and the Fertilizer That Fixes It
Melon nutrient deficiency is one of the first things to check when the leaves of your milon (melon) turn yellow, purple or burnt at the edges. On Philippine farms the usual ones are nitrogen, potassium, magnesium, molybdenum, calcium, boron and phosphorus. This guide shows where each one starts, how to be sure, and the fertilizer that fixes it.
Start with one question: did the change begin on the old leaves or on the young ones? Nitrogen, potassium, magnesium, molybdenum and phosphorus move inside the plant, so a shortage shows on the old, lower leaves first. But calcium and boron stay where the plant first put them, so the young leaves and the growing tip show it first. After that, the color and the pattern narrow down which melon nutrient deficiency you have, and a soil test confirms it. Each one below has its signs, its causes and its fix.
Melon nutrient deficiency signs, old leaves and young leaves
Shows first on the old leaves
| Nutrient | Where it starts | What you see | Fix with |
|---|---|---|---|
| Nitrogen | old, lower leaves, the whole plant | Old leaves pale and yellow up the vine, and fruits are small and misshapen. | Urea 46 0 0, Ammonium sulfate 21 0 0 |
| Potassium | old, lower leaves, leaf edges and tips | Old leaves scorch and cup up, and fruits are poorly flavoured and spotted. | Sulfate of potash 0 0 50, Muriate of potash 0 0 60 |
| Magnesium | old, lower leaves, between the veins | Oldest leaves yellow between the veins while fruits are swelling, and the yellow patches fall out. | Magnesium sulfate (Epsom salt), Dolomite |
| Molybdenum | the whole plant, between the veins | On acid soil, crown leaves turn pale between the veins as vines start to run, then leaf edges burn. | Sodium molybdate, Agricultural lime |
| Phosphorus | old, lower leaves, the whole plant | Purplish leaves along the veins, small stiff dark young leaves and weak vines. | Complete 14 14 14, Ammonium phosphate 16 20 0 |
Shows first on the young leaves
| Nutrient | Where it starts | What you see | Fix with |
|---|---|---|---|
| Calcium | young leaves and the tip, fruit, grain or tubers | New leaves crinkle and hook, vine tips die, and fruits are small, soft or tasteless. | Agricultural lime, Dolomite |
| Boron | young leaves and the tip, fruit, grain or tubers | Young fruits drop, and fruits show yellow streaks, corky marks and cracks. | Borax, Solubor (sodium borate) |
Before you buy fertilizer for a melon nutrient deficiency
So use the table to pick the likeliest melon nutrient deficiency, then read its section below. Also keep in mind that dry soil, standing water, cold nights, a pest or a disease can look the same. That is why it pays to check the roots and the whole field first.
Nitrogen deficiency in melon
Older leaves turn pale to light green, yellow and drop, and the yellowing moves up the shoot. Vines are stunted and fruits are pale, small and misshapen, so yield falls. You see it most at this stage: vine growth and fruit set.
Why nitrogen deficiency happens in milon
Sandy soils, heavy rain or irrigation, low organic matter, and no side dressing before fruit set.
How to tell it apart
Magnesium shortage, very common in melon, leaves the veins green on old leaves. Molybdenum shortage on acid soil shows pale crown leaves at vining. To be sure, old leaves yellow first. Soil test and leaf tissue test.
What to apply for nitrogen deficiency
Side dress urea or ammonium sulfate based on the soil test, before the fruits form. For a quick fix, give a urea leaf spray at 10 grams per liter of water (160 grams in a 16 liter sprayer) every 15 days for Cucumis melo. Side dress 5 to 10 grams of Urea 46 0 0 a plant, about 1 to 2 bags per hectare, every two to three weeks from flowering, and water it in.
- Urea 46 0 0
- Ammonium sulfate 21 0 0
- Calcium nitrate
- Complete 14 14 14
Sold here with nitrogen: Atlas Granular Urea (46 0 0) by Atlas Fertilizer, Crown Champion Ammonium Sulfate by Aqua Hydroponic Prime Ventures (21 0 0 with 24 percent sulfur), Agripower 46 0 0 (Locally Blended) Coated by Green Acres Agri Tech and Calcipro by Ramgo (15.5 0 0 with 18.8 percent calcium). Check the FPA registration on the bag and follow the label rate. For the how and when, see our guide to urea fertilizer, and the page on nitrogen deficiency in every crop. In anee.io, Anee, the smart farm technician, reads a photo of the leaf and tells you which nutrient is short.
To keep it away, add manure and split nitrogen. Too much nitrogen late in the season can cause fruit blemishes and rots.
Potassium deficiency in melon
Older leaves yellow and scorch, cup and curl upward, with sunken dead spots along the midrib. Vines die back, stems weaken and fewer female flowers form. Fruits can be spotted, off flavoured and less sweet. You see it most at this stage: fruit filling. Melon uses more potassium than nitrogen and most of it moves from the leaves into the fruit.
Why potassium deficiency happens in milon
Sandy or acid soils, heavy rain, and too little potash during fruit filling.
How to tell it apart
Magnesium shortage yellows between the veins first. Potassium burns the edges first. To be sure, soil test for potassium and a leaf tissue test.
What to apply for potassium deficiency
Apply muriate of potash or sulfate of potash based on the soil test, in split doses. For immediate relief, give a morning spray of sulfate of potash at 10 grams per liter of water (160 grams in a 16 liter sprayer) with a sticker. A usual dose is 1 to 2 bags of Muriate of potash 0 0 60 or Sulfate of potash 0 0 50 per hectare, split from flowering to fruit fill.
- Sulfate of potash 0 0 50
- Muriate of potash 0 0 60
- Potassium nitrate 13 0 46
Sold here with potassium: Atlas Muriate of Potash (MOP) by Atlas Fertilizer (0 0 60), Simplot Sulfate 0 0 50 by Nutranta, Potassium Nitrate by Parafield (13 0 46) and Qrop Mix Production 14 0 23 plus 13 Cao by Farmtech Agriland (14 0 23 with 9.3 percent calcium). Check the FPA registration on the bag and follow the label rate. For the how and when, see our guide to potash fertilizer, and the page on potassium deficiency in every crop.
To keep it away, give potash at planting and again at fruit set, and keep potassium, calcium and magnesium in balance. Keep organic matter up with compost, manure or crop residues.
Magnesium deficiency in melon
Yellowing between the veins starts on the oldest leaves and moves up the vine. Yellow tissue may brown, die and drop out, leaving a shot hole look, or turn red with spotted dead patches. Older leaves drop early and yield falls. Melon shows this shortage more than squash, cucumber and other gourds. You see it most at this stage: fast growth while the fruits enlarge.
Why magnesium deficiency happens in milon
Sandy soils with low holding capacity, low pH, dry years, and heavy potash, lime or ammonium fertilizer.
How to tell it apart
Manganese toxicity on very acid soil can look like it, with water soaked areas under the leaves and yellow or bronze spots on top. A soil pH test tells them apart. To be sure, soil test for magnesium, potassium and pH, and a leaf tissue test.
What to apply for magnesium deficiency
Keep the pH near 6.5, and give Epsom salt through drip lines when needed. Leaf sprays rarely fix a serious shortage. Give magnesium sulfate in a band near the plants at about 80 kg per hectare for Cucumis melo. Do not apply magnesium with potash. For quick help, spray Magnesium sulfate at 1 to 2 percent (160 to 320 grams in a 16 liter sprayer) two or three times, 10 to 14 days apart.
- Magnesium sulfate (Epsom salt)
- Dolomite
- Magnesium oxide
Sold here with magnesium: Dolomite by A6 Agrisource (24 percent calcium and 11 percent magnesium), Agsmart Kieserite Granule (20 percent sulfur and 16.3 percent magnesium), DDDD Planter's Choice Magnesium Sulphate Monohydrate by Modern Time (15.1 percent magnesium) and Zetryl MAG 9 by Zetryl Chem (9 percent magnesium). Check the FPA registration on the bag and follow the label rate. For the how and when, see our guide to complete fertilizer, and the page on magnesium deficiency in every crop.
To keep it away, apply dolomitic lime before planting on acid soil and avoid heavy potassium, calcium or ammonium fertilizer. Test the soil every two or three years.
Molybdenum deficiency in melon
Leaves near the crown turn pale green to slightly yellow between the veins around the time plants begin to vine. As it worsens, leaf edges and areas between veins burn and die, and growth stops. Other cucurbits on the same soil often show no signs. You see it most at this stage: start of vining.
Why molybdenum deficiency happens in milon
Heavy soils with pH below 6, and heavy ammonium fertilizer through drip lines, which acidifies the root zone and can also bring manganese toxicity.
How to tell it apart
Nitrogen shortage yellows old leaves evenly. Magnesium shortage starts on the oldest leaves and comes later, during fruiting. To be sure, soil pH test. A soil pH test confirms the risk. A test spray of sodium molybdate on a few plants confirms the cause when they green up.
What to apply for molybdenum deficiency
Spray sodium molybdate on the leaves and keep the pH at 6.0 to 6.5. For a leaf spray, mix about 50 grams of sodium molybdate in 100 liters of water. Before the next crop, mix about 1 kg per hectare into the fertilizer. Spray Sodium molybdate at 0.05 to 0.1 percent (8 to 16 grams in a 16 liter sprayer) once or twice on young plants.
- Sodium molybdate
- Agricultural lime
- Dolomite
Sold here with molybdenum: Tierramino Molybdenum by Unilox Far East Resources (16 percent molybdenum) and YaraVita Teprosyn Mo (0 15 0 with 15.3 percent molybdenum). Check the FPA registration on the bag and follow the label rate. For the how and when, see our guide to foliar fertilizer, and the page on molybdenum deficiency in every crop.
To keep it away, lime acid soil to pH 6 to 6.5 ahead of planting and avoid heavy ammonium feeding. Test the soil every two or three years.
Calcium deficiency in melon
Young leaves show yellow stripes beside the midrib, crinkle, yellow at the edges and become brittle, and the spaces between leaves shorten. Growing tips die back and roots are stunted. Fruits may be small and tasteless or fail to form. You see it most at this stage: vine growth and early fruiting.
Why calcium deficiency happens in milon
Very acid soils, uneven watering, excess phosphorus and low boron. Only a small share of the plant's calcium reaches the fruit, so steady water matters.
How to tell it apart
Boron shortage also deforms new growth and drops young fruit. To be sure, soil test for calcium, pH and boron.
What to apply for calcium deficiency
On acid soil, lime by the soil test: usually 1 to 3 tons of Agricultural lime or Dolomite per hectare, mixed in 2 to 4 weeks before planting. Gypsum on soil that is not acid. Water evenly.
- Agricultural lime
- Dolomite
- Gypsum
- Calcium nitrate
Sold here with calcium: Micronized Activated Calcite by CMCS Agricultural Products (37.6 percent calcium), Dolomite by A6 Agrisource (24 percent calcium and 11 percent magnesium), Titon Pro by Vast Agro (27.2 percent calcium, 6.1 percent silicon and 3.6 percent magnesium) and Calcipro by Ramgo (15.5 0 0 with 18.8 percent calcium). Check the FPA registration on the bag and follow the label rate. For the how and when, see our guide to fertilizer for tomatoes, and the page on calcium deficiency in every crop.
To keep it away, lime before planting and keep calcium, potassium and magnesium in balance.
Boron deficiency in melon
New leaves are malformed and the plant becomes bushy as buds die. Young fruits drop or abort, and fruits show yellow streaks and corky skin marks. Mature fruits may be small, light or cracked. You see it most at this stage: flowering and fruit set.
Why boron deficiency happens in milon
Sandy soils, overlimed soils, low organic matter and drought.
How to tell it apart
Poor pollination also drops young fruits but leaves stay normal. To be sure, soil test for boron and a leaf tissue test. In a soil test, less than 0.5 ppm of boron is low.
What to apply for boron deficiency
Try borax in the soil at about 10 kg per hectare or a borax spray at 1 gram per liter of water (16 grams in a 16 liter sprayer). Muskmelon has a medium boron need, about 2.2 kg of boron per hectare before planting. Do not mix borax with calcium or ammonium fertilizer.
- Borax
- Solubor (sodium borate)
Sold here with boron: Etifert 11 (Borax Decahydrate) by Zetryl Chem (11 percent boron), Fertibagra 15G by Unilox Far East Resources (14.6 percent boron), B17 (Boric Acid) by Newman Chemicals (17 percent boron) and Better Yield by Bacphil Planters Fertilizer (0 0 0.9 with 10 percent boron). Check the FPA registration on the bag and follow the label rate. For the how and when, see our guide to foliar fertilizer, and the page on boron deficiency in every crop.
To keep it away, add a small boron dose to the basal fertilizer on sandy fields. Test the soil every two or three years. Keep organic matter up with compost, manure or crop residues.
Phosphorus deficiency in melon
Leaves turn purple, especially along the veins. Shoots are short and thin, young leaves are small, stiff and dark green, and leaves look dull and shrivelled. Vigour, fruit set and yield are poor. You see it most at this stage: early growth, and from flowering to fruit fill, when melon needs the most phosphorus.
Why phosphorus deficiency happens in milon
Acid or iron rich soils, low organic matter, cold or waterlogged soil, and no phosphorus at planting.
How to tell it apart
Root knot nematodes also stunt vines. To be sure, soil test for available phosphorus and pH.
What to apply for phosphorus deficiency
Apply phosphorus in the hill based on the soil test. Use single superphosphate for a quick fix. Uptake is best near pH 6.2 to 7.0. A usual basal dose is 4 to 6 bags of Complete 14 14 14 per hectare, 10 to 20 grams a hill, mixed into the soil at transplanting.
- Complete 14 14 14
- Ammonium phosphate 16 20 0
- Single superphosphate
Sold here with phosphorus: Philphos 18 46 0 (Di Ammonium Phosphate), Atlas Super Gro (16 20 0) by Atlas Fertilizer, Amigo Planters Granular Single Super Phosphate by La Filipina (0 18 0 with 11 percent sulfur) and Triple Super Phosphate by Newman Chemicals (0 46 0). Check the FPA registration on the bag and follow the label rate. For the how and when, see our guide to 16 20 0 fertilizer, and the page on phosphorus deficiency in every crop.
To keep it away, use complete fertilizer or 16 20 0 in the hill at planting.
A soil test is the surest check for any melon nutrient deficiency. Before you buy, ask your Municipal Agriculture Office where to send a soil sample. The DA regional soil laboratories test soil, and the result says how much of each fertilizer your milon needs. That saves money, because extra fertilizer is money lost.
Open the Nutrient Deficiency Finder, pick milon, 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
- The cropping calendar dates every fertilizer application of your season
Melon nutrient deficiency questions
Why are my milon leaves turning yellow?
What fertilizer fixes nitrogen deficiency in melon?
What fertilizer fixes potassium deficiency in melon?
What fertilizer fixes magnesium deficiency in melon?
How do I know which nutrient my milon lacks?
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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