Pechay Nutrient Deficiency: Signs, Causes and the Fertilizer That Fixes It
Pechay nutrient deficiency is one of the first things to check when the leaves of your petsay (pechay) turn yellow, purple or burnt at the edges. On Philippine farms the usual ones are nitrogen, calcium, potassium, phosphorus, magnesium, boron and sulfur. 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, phosphorus and magnesium move inside the plant, so a shortage shows on the old, lower leaves first. But calcium, boron and sulfur 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 pechay nutrient deficiency you have, and a soil test confirms it. Each one below has its signs, its causes and its fix.
Pechay 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 | Outer leaves turn pale yellow and the plants stay small and slow. | Urea 46 0 0, Ammonium sulfate 21 0 0 |
| Potassium | old, lower leaves, leaf edges and tips | Older leaves get a light brown, dry band along the edges that curls up. | Complete 14 14 14, Muriate of potash 0 0 60 |
| Phosphorus | the whole plant, old, lower leaves | Seedlings and young plants stay small and dark, sometimes with purple undersides. | Complete 14 14 14, Ammonium phosphate 16 20 0 |
| Magnesium | old, lower leaves, between the veins | Outer leaves yellow between the veins while the veins stay green. | Magnesium sulfate (Epsom salt), Dolomite |
Shows first on the young leaves
| Nutrient | Where it starts | What you see | Fix with |
|---|---|---|---|
| Calcium | young leaves and the tip, leaf edges and tips | The tips and edges of the young centre leaves turn brown and dry, and soft rot can follow. | Agricultural lime, Dolomite |
| Boron | young leaves and the tip | New centre leaves come out small, thick and crinkled, and stalks may crack. | Borax, Solubor (sodium borate) |
| Sulfur | young leaves and the tip, the whole plant | Young centre leaves turn pale with blue green veins and purple undersides. | Ammonium sulfate 21 0 0, Gypsum |
Before you buy fertilizer for a pechay nutrient deficiency
So use the table to pick the likeliest pechay 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 pechay
The outer, older leaves turn pale green and then yellow, and the yellowing spreads to the whole plant. Leaves stay small and growth slows, so plants are light at harvest. Old leaves may get reddish tints and die early. You see it most at this stage: from transplanting to harvest. Pechay is harvested only three to four weeks after transplanting, so any shortage shows fast.
Why nitrogen deficiency happens in petsay
Sandy soils, heavy rain or daily watering that leaches nitrogen, low organic matter, and missed weekly drenches.
How to tell it apart
Sulfur shortage starts on the young centre leaves. Root damage from clubroot or waterlogging also yellows plants. To be sure, old leaves yellow first. A soil test for organic matter and nitrogen, and a quick test drench on a few plants.
What to apply for nitrogen deficiency
The drench urea dissolved in 16 liters of water at 150 ml per hill, using 75 grams of urea in the first week, 150 grams in the second, 225 grams in the third and 300 grams in the fourth. Give a urea leaf spray at 10 grams per liter of water (160 grams in a 16 liter sprayer) for cole crops. Water after feeding. Side dress 1 to 2 bags of Urea 46 0 0 per hectare, about 5 grams a plant, two and four weeks after transplanting, and water it in.
- Urea 46 0 0
- Ammonium sulfate 21 0 0
- Complete 14 14 14
- Chicken manure
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), Hyfer Urea Max (Locally Blended Coated) by Agrotiger (44 0 0) and Agripower 25 0 0 (Locally Blended) Coated by Green Acres Agri Tech. 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, mix chicken manure or compost into the beds before planting, and keep up the weekly drench. Let a soil test and the crop's color set the season's nitrogen. Split the nitrogen into two or three doses.
Calcium deficiency in pechay
The tips and edges of young, fast growing leaves die and turn brown, and the damage spreads inward. Young leaves can be cupped or claw shaped. Soft rot bacteria often enter the burnt tissue, so the heart of the plant turns slimy. You see it most at this stage: fast growth in hot, dry weather, close to harvest.
Why calcium deficiency happens in petsay
Poor calcium movement into fast growing leaves, mainly from uneven watering, plus acid sandy soils, high nitrogen, potassium or ammonium, and high humidity.
How to tell it apart
Bacterial soft rot starts as a wet, smelly rot. With tip burn the edges die first and rot comes later. To be sure, look at the youngest leaves for burnt tips. Soil test for calcium and pH.
What to apply for calcium deficiency
Water evenly every day, and do not let beds dry out. On acid soil, try lime at about 250 kg per hectare when pH is 5.5 to 6, or about 840 kg per hectare in two doses when pH is 3.5 to 4.5. Gypsum on soil that is not acid. Lime 2 to 4 weeks before planting. Calcium sprays go on young fruit from fruit set.
- 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 Crown Champion Nitrogen Calcium Compound (Cal Nit) by Aqua Hydroponic Prime Ventures (15 0 0 with 18 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 acid beds before planting (pechay grows best at pH 5.5 to 6.5), keep watering steady, and avoid heavy ammonium fertilizer. Test the soil every two or three years. Keep potash in balance with magnesium and calcium.
Potassium deficiency in pechay
The edges of older leaves turn yellow, then light brown and dry, and the band spreads inward. Leaf edges curl upward and the plant grows less. You see it most at this stage: mid growth to harvest.
Why potassium deficiency happens in petsay
Sandy or acid soils, heavy rain and daily watering that leach potassium, and fertilizing with urea only.
How to tell it apart
Fertilizer burn from a strong drench poured on the leaves also browns edges. It appears suddenly after feeding. To be sure, soil test for potassium.
What to apply for potassium deficiency
Include potash in the basal fertilizer, such as complete 14 14 14, and apply muriate of potash based on the soil test. For a quick fix, give a morning spray of sulfate of potash at 10 grams per liter of water (160 grams in a 16 liter sprayer) for cabbage, a close relative. A usual dose is 1 to 2 bags of Muriate of potash 0 0 60 per hectare, split between transplanting and the first side dress.
- Complete 14 14 14
- Muriate of potash 0 0 60
- Sulfate of potash 0 0 50
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, use complete fertilizer at bed preparation instead of urea alone. Keep organic matter up with compost, manure or crop residues.
Phosphorus deficiency in pechay
Growth slows sharply while leaves may stay dark green, so the problem is easy to miss. Some plants show purple or reddish undersides on the older leaves and weak roots. You see it most at this stage: seedling and the first two weeks after transplanting.
Why phosphorus deficiency happens in petsay
Acid or iron rich soils that hold phosphorus, low organic matter, cold or waterlogged soil, and fertilizing with urea only.
How to tell it apart
Root problems such as clubroot or nematodes also stunt plants. Check the roots. To be sure, soil test for available phosphorus and pH.
What to apply for phosphorus deficiency
Use complete 14 14 14 or 16 20 0 in the bed before planting, based on the soil test, and lime very acid soil. Use single superphosphate for a quick correction in cole crops. A usual basal dose is 4 to 6 bags of Complete 14 14 14 per hectare, about 10 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, apply a phosphorus fertilizer and manure at bed preparation, and keep pH between 5.5 and 6.5.
Magnesium deficiency in pechay
Older leaves turn yellow between the veins, starting at the edges, while the veins stay green. Later the yellow areas can turn orange or die. Chinese cabbage, a close cousin of pechay, is very prone to it, so watch pechay closely. You see it most at this stage: mid growth to harvest.
Why magnesium deficiency happens in petsay
Low pH soils, soils high in potassium, heavy potash fertilizer, sandy soils and heavy rain.
How to tell it apart
Nitrogen shortage yellows the whole leaf evenly, veins included. To be sure, soil test for magnesium, potassium and pH.
What to apply for magnesium deficiency
Spray magnesium sulfate on the leaves for quick relief. For cole crops give magnesium sulfate in a band near the plants at about 80 kg per hectare. Do not apply it together 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
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, use dolomite instead of plain lime on acid beds. Test the soil every two or three years.
Boron deficiency in pechay
Young leaves stay small, curl and become deformed and brittle, with yellow mottling along the edges. Stalks and midribs may split or go corky, and a bad case kills the growing tip. Plants stay stunted and open. You see it most at this stage: mid growth, after dry spells or on limed beds.
Why boron deficiency happens in petsay
Sandy soils where boron leaches, alkaline or overlimed soils, low organic matter, high nitrogen and drought. Crucifers need more boron than most crops.
How to tell it apart
Calcium tip burn kills leaf edges but does not make leaves thick and crinkled. Aphid feeding also curls young leaves. 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
For cole crops, give borax at about 10 kg per hectare in the soil or a spray at 1 gram per liter of water (16 grams in a 16 liter sprayer). Do not mix borax with lime or ammonium fertilizer, and do not repeat without a test, because too much boron burns leaves. Give boron before flowering: flowers and fruit set need it most.
- 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 dose of borax to the basal fertilizer on sandy beds. Test the soil every two or three years. Keep organic matter up with compost, manure or crop residues.
Sulfur deficiency in pechay
Plants are small and spindly. Young and middle leaves turn pale between the veins, with the veins standing out in a blurred blue green pattern. The leaves cup and may become brittle. The undersides can turn purple or bronze. You see it most at this stage: early growth on light soils after heavy rain.
Why sulfur deficiency happens in petsay
Light, sandy soils with low organic matter after wet weather. Fertilizing with urea and muriate of potash only, which carry no sulfur.
How to tell it apart
Nitrogen shortage starts on the outer, older leaves. To be sure, A leaf tissue test is the most reliable check, since sulfate leaches and soil tests can mislead. In a soil test, less than 10 ppm of sulfate sulfur is low.
What to apply for sulfur deficiency
Use ammonium sulfate for part of the nitrogen. On light soils, give about 20 kg of sulfur per hectare, roughly 85 kg of ammonium sulfate. Leaf sprays may help but are not a sure cure. Give it at planting or with the first side dress.
- Ammonium sulfate 21 0 0
- Gypsum
- Sulfate of potash 0 0 50
Sold here with sulfur: Crown Champion Ammonium Sulfate by Aqua Hydroponic Prime Ventures (21 0 0 with 24 percent sulfur), Philphos Gypsum (22.2 percent calcium and 17.4 percent sulfur), Harvester Sulphate of Potash by Universal Harvester (0 0 50 with 17.5 percent sulfur) and Agsmart Kieserite Granule (20 percent sulfur and 16.3 percent magnesium). Check the FPA registration on the bag and follow the label rate. For the how and when, see our guide to ammonium sulfate fertilizer, and the page on sulfur deficiency in every crop.
To keep it away, use ammonium sulfate in the drench or side dressing every crop and add manure. Test the soil every two or three years.
A soil test is the surest check for any pechay 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 petsay needs. That saves money, because extra fertilizer is money lost.
Open the Nutrient Deficiency Finder, pick petsay, 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
Pechay nutrient deficiency questions
Why are my petsay leaves turning yellow?
What fertilizer fixes nitrogen deficiency in pechay?
What fertilizer fixes calcium deficiency in pechay?
What fertilizer fixes potassium deficiency in pechay?
How do I know which nutrient my petsay lacks?
- Yara UK: Nitrogen deficiency in cabbage
- Yara UK: Calcium deficiency in cabbage
- Yara UK: Potassium deficiency in cabbage
- Yara UK: Phosphorus deficiency in cabbage
- Yara UK: Magnesium deficiency in cabbage
- Yara UK: Boron deficiency in cabbage
- Teagasc: Sulphur requirements of brassica crops (technical note 2020)
- Yara UK: Sulfur deficiency in cabbage
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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