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For Smallholder Farmers in East & Southern Africa
Maize • Beans • Tomato • Sorghum • Cassava • Groundnuts & more
INCLUDES:
✓ How to read your crop’s leaves
✓ Monocot vs Dicot symptom differences
✓ Quick diagnosis chart
✓ 8-step management guide
Keep this guide in your digital field kit
HOW TO USE THIS GUIDE
When your crop looks sick, the leaves are your first clue. This guide helps you identify which nutrient your crop is missing; so you can fix the right problem, not waste money on the wrong fertilizer.
STEP 1: Identify your crop type
Is it a monocot (narrow leaves, parallel veins; like maize, sorghum, millet, rice, wheat, sugarcane, banana)?
Or a dicot (broad leaves, branching veins : like beans, tomatoes, cassava, groundnuts, cabbage, sunflower)?
STEP 2: Check WHICH leaves are affected
Old/lower leaves affected first → the plant is low in a mobile nutrient (Nitrogen, Phosphorus, Potassium, Magnesium).
New/young leaves affected first → the plant is low in an immobile nutrient (Calcium, Iron, Zinc, Boron, Manganese).
STEP 3: Match what you see to the tables below
Find your crop type, then look for the symptom that best matches what you see in the field.
QUICK DIAGNOSIS: WHAT DO YOU SEE?
Use this table first. Match the symptom you see, then check the detailed tables below to confirm.
| What you see on the leaf | Monocot crop (e.g. maize) | Dicot crop (e.g. beans/tomato) | Likely nutrient missing |
| Yellowing starts on OLD leaves | V-shape from tip down midrib | Uniform pale yellow on whole leaf | Nitrogen (N) |
| Purple or dark green colour | Leaf underside and edges purple | Dark green with bronze tinge below | Phosphorus (P) |
| Brown edges/tips on OLD leaves | Scorch along full length of leaf edge | Irregular scorch on broad leaf margin | Potassium (K) |
| Yellowing between veins, OLD leaves | Alternating yellow-green stripes | Green vein skeleton on yellow leaf | Magnesium (Mg) |
| Yellowing between veins, YOUNG leaves | Pale stripes on newest leaves | Vivid green skeleton on yellow | Iron (Fe) or Manganese (Mn) |
| NEW leaves deformed or stuck | Leaves cannot open, twisted, fused | Tips curl down, crinkle, or die back | Calcium (Ca) or Boron (B) |
| Small leaves, stunted new growth | White/pale bands beside midrib, short internodes | Tiny clustered leaves (rosette) | Zinc (Zn) |
| Yellowing on YOUNG leaves (uniform) | Pale yellow-green on newest growth | Young leaves yellow (not old) | Sulfur (S) |
⚠ Iron (Fe) and Manganese (Mn) look very similar. A soil or tissue test is needed to tell them apart.
SECTION 1: MONOCOT CROPS
Maize • Sorghum • Millet • Rice • Wheat • Sugarcane • Banana
Monocot leaves have PARALLEL veins running lengthwise. Symptoms often appear as STRIPES or STREAKS along the leaf, not patches.
| NUTRIENT | CROPS AFFECTED | WHERE TO LOOK | WHAT YOU SEE | URGENCY |
| Nitrogen (N) | Maize, Sorghum, Millet, Rice, Wheat | Older (lower) leaves | V-shaped yellowing from leaf tip down midrib. Whole plant pale green. Slow growth, thin stems. | HIGH |
| Phosphorus (P) | Maize, Sorghum, Wheat, Rice | Whole plant, older leaves first | Purple or reddish colour on leaf undersides and edges. Dull dark-green upper surface. Slow flowering and grain fill. | HIGH |
| Potassium (K) | Maize, Sugarcane, Banana, Rice | Older leaf margins and tips | Yellowing then brown scorching along full leaf edge from tip downward (“firing”). Weak stems, poor grain quality. | HIGH |
| Magnesium (Mg) | Maize, Sorghum, Millet | Older leaves | Yellow-green stripes alternating between parallel veins. Veins stay green. Striped appearance along leaf length. | MEDIUM |
| Calcium (Ca) | Maize, Sorghum, Wheat | New/young leaves (growing tip) | New leaves stuck, twisted, or fused — cannot open properly (“buggy whipping” in maize). Ragged leaf edges. | HIGH |
| Iron (Fe) | Maize, Sorghum, Rice, Millet | Young leaves | Yellow stripes between parallel veins on newest leaves. Veins stay green. Severe: whole leaf turns pale yellow or white. | MEDIUM |
| Zinc (Zn) | Maize, Rice, Sorghum | Young leaves | Broad white or pale yellow bands on either side of the midrib. “White bud” in severe cases. Short internodes. | HIGH |
| Manganese (Mn) | Maize, Wheat, Rice | Young leaves | Similar to iron deficiency — pale stripes between veins on new growth. Veins remain green. Tissue may die in severe cases. | MEDIUM |
| Boron (B) | Maize, Sugarcane | Growing tip and young leaves | Growing tip dies back. Leaves thick, brittle, and distorted. White or pale stripes near leaf base. Ear/tassel abnormalities. | MEDIUM |
| Copper (Cu) | Wheat, Maize | Young leaves | Tips of new leaves turn white or pale yellow. Leaves may wilt and curl. Poor grain set. | LOW |
| Sulfur (S) | Maize, Wheat, Rice | Young leaves | Uniform yellowing of young leaves (similar to nitrogen but affects new growth first). Pale yellow-green plant overall. | MEDIUM |
SECTION 2: DICOT CROPS
Beans • Cowpeas • Groundnuts • Tomato • Cassava • Cabbage • Sunflower • Potato
Dicot leaves have BRANCHING, NET-LIKE veins. Symptoms appear as PATCHES, PATCHES WITH GREEN VEINS, or IRREGULAR EDGE DAMAGE on broad leaves.
| NUTRIENT | CROPS AFFECTED | WHERE TO LOOK | WHAT YOU SEE | URGENCY |
| Nitrogen (N) | Beans, Cowpeas, Tomato, Cabbage, Cassava | Older (lower) leaves | Uniform pale yellow-green across whole old leaves. Leaves may drop early. Stunted plant, small pale leaves throughout. | HIGH |
| Phosphorus (P) | Beans, Groundnuts, Tomato, Potato | Older leaves, stems | Dark green or purple-bronze colour on leaf undersides. Slow root development. Delayed flowering. Poor fruit/seed set. | HIGH |
| Potassium (K) | Tomato, Potato, Beans, Cassava, Banana | Older leaf margins | Irregular brown scorch following the outline of broad leaf edges. Older leaves affected first. Soft or poorly formed fruits. | HIGH |
| Magnesium (Mg) | Tomato, Beans, Cassava, Coffee | Older leaves | Classic interveinal chlorosis — green vein skeleton on yellow background. Very distinct in broad-leaved crops. Starts at leaf centre. | MEDIUM |
| Calcium (Ca) | Tomato, Pepper, Cabbage, Lettuce | Young leaves and fruit | Young leaves curl downward, crinkle, or die at tips. Blossom-end rot (black sunken base) in tomato and pepper fruits. Tip burn in cabbage. | HIGH |
| Iron (Fe) | Beans, Groundnuts, Tomato, Soybean | Young leaves | Bright yellow leaf with clear green vein network — like a green skeleton. Most vivid in legumes. Alkaline or waterlogged soils common cause. | MEDIUM |
| Zinc (Zn) | Beans, Tomato, Citrus, Cassava | Young leaves | Small, abnormally narrow leaves clustered together (“little leaf” or rosette). Interveinal chlorosis. Shortened internodes, stunted plant. | HIGH |
| Manganese (Mn) | Beans, Groundnuts, Soybean, Cowpeas | Young leaves | Interveinal chlorosis similar to iron but less vivid. Grey or tan spots may appear in the yellow areas between veins. | MEDIUM |
| Boron (B) | Sunflower, Cabbage, Tomato, Groundnuts, Cowpeas | Growing tips, young leaves, fruit | Shoot tip dies. Young leaves thick, brittle, distorted. Cauliflower heads turn brown inside. Hollow fruit or stem. Cracked fruit skin. | MEDIUM |
| Copper (Cu) | Tomato, Beans, Sunflower | Young leaves | Wilting and bluish-green discolouration of young leaves. Tips die back. Poor fruit development. More common in sandy or peat soils. | LOW |
| Sulfur (S) | Beans, Groundnuts, Sunflower, Cabbage | Young leaves | Uniform yellowing of young leaves first (opposite to nitrogen). Whole plant may turn pale. Common in soils low in organic matter. | LOW |
| Molybdenum (Mo) | Beans, Cowpeas, Groundnuts (legumes) | Older leaves | Yellowing and upward cupping (“whiptail”) of older leaves. Narrow, strap-like leaves. Poor nitrogen fixation in legume root nodules. | LOW |
WHAT TO DO ABOUT IT: 8-STEP MANAGEMENT GUIDE
Start with the lowest-cost options. Build soil health over time.
| STEP | ACTION | WHAT TO DO |
| 1 | Soil test first | Before buying any fertilizer, test your soil for pH and nutrients. Ask your local extension officer or agro-dealer. A simple test prevents wasted money. |
| 2 | Fix soil pH | Most deficiencies are made worse by wrong pH. Apply agricultural lime if soil is too acidic (common in red soils and high rainfall areas). Target pH 6.0–7.0. |
| 3 | Add compost and manure | Apply well-rotted animal manure or compost before planting. This adds nutrients slowly and improves the soil’s ability to hold moisture and nutrients long-term. |
| 4 | Use legumes | Intercrop maize with beans or cowpeas. Rotate cereals with legumes each season. Legumes fix nitrogen from the air — free fertilizer for your next crop. |
| 5 | Apply fertilizer wisely | Use soil test results to guide what you apply. Split nitrogen applications — some at planting, more at knee-high stage. Place fertilizer near roots, not scattered. |
| 6 | Foliar spray for quick fix | If you spot a deficiency mid-season, spray micronutrient solution directly on leaves. Quick relief — especially for zinc, iron, and boron. Available from agro-dealers. |
| 7 | Protect your roots | Control Striga, nematodes, and root diseases that prevent nutrient uptake. Improve drainage in flooded areas. Healthy roots = healthy nutrient absorption. |
| 8 | Don’t burn crop residues | Chop and incorporate maize stalks, bean vines, and other crop residues back into the soil after harvest. Nutrients return to the soil as they break down. |
KEY REMINDERS
• Always diagnose before you treat. The wrong amendment makes problems worse.
• Most micronutrient deficiencies (zinc, iron, boron) are caused by wrong soil pH — fix the pH first.
• Foliar sprays give fast relief mid-season but do not fix the underlying soil problem.
• Compost and manure are your cheapest, most reliable nutrient sources — use them every season.
• Legumes are free nitrogen. Always rotate or intercrop with beans, cowpeas, or groundnuts.
• Never burn your crop residues. Every stalk you burn is nutrients lost forever.
Your soil is the foundation of everything you grow.
Small, consistent improvements to your soil compound over time.
