Africa's staple cereal and the crop where nitrogen management decides yield. Most 'disease' calls on maize turn out to be nutrient stress or fall armyworm damage rather than a pathogen.
- Grown in
- Nigeria, Kenya, Ghana, Tanzania, India, Mexico, USA
- Season
- Rain-fed, 90–140 days depending on variety
- Soil & pH
- Deep fertile loam, pH 5.8–7.0, very high nitrogen demand
What to scout for on Maize / Corn
- Inverted V-shaped yellowing from the leaf tip — classic nitrogen deficiency
- Long grey-green cigar lesions — northern leaf blight
- Rust pustules that rub off orange on the thumb
- Ragged windowpane feeding in the whorl — fall armyworm, not disease
Diseases that attack Maize / Corn
Leaf Spot
Septoria, Cercospora, Alternaria spp.
Rust Disease
Puccinia, Uromyces spp.
Nitrogen Deficiency
Abiotic — nutrient stress
Products you can buy for Maize / Corn
Typical registered products for the diseases above, with active ingredient, mixing rate, spray interval and pre-harvest interval. Rotate FRAC/IRAC groups to avoid resistance.
Urea 46-0-0
Active ingredient: Urea nitrogen 46%
- Dose:
- 100–150 kg/ha split, or 5 g per litre as a 2% foliar spray
- Interval:
- Split into 2–3 side-dressings across the growth cycle
- PHI:
- Not applicable
Incorporate into moist soil within a day — surface urea can lose 30% of its nitrogen to volatilisation.
NPK 15-15-15 compound
Active ingredient: Balanced N-P-K
- Dose:
- 200–300 kg/ha at planting
- Interval:
- Basal dose at planting or transplanting
- PHI:
- Not applicable
The correct starting point when no soil test exists; follow up with nitrogen-only top-dressing.
Calcium ammonium nitrate (CAN 27%)
Active ingredient: Ammonium nitrate + calcium
- Dose:
- 150–200 kg/ha top-dressed
- Interval:
- At 3–4 weeks and again at 7–8 weeks after emergence
- PHI:
- Not applicable
Preferred over urea on acidic soils because it supplies calcium and does not further acidify.
Well-rotted farmyard manure / compost
Active ingredient: Organic nitrogen
- Dose:
- 10–20 t/ha incorporated before planting
- Interval:
- Once per season
- PHI:
- Not applicable
Slow-release nitrogen plus the organic matter that keeps mineral fertiliser working in the following seasons.
Tebuconazole 25% EC
Active ingredient: Tebuconazole
- Dose:
- 1 ml per litre (500 ml–1 L/ha)
- Interval:
- Every 14–21 days, 2 sprays per season
- PHI:
- 21–35 days on cereals
The standard cereal-rust curative. Apply at first pustule, and again at flag-leaf if pressure continues.
Propiconazole 25% EC
Active ingredient: Propiconazole
- Dose:
- 1 ml per litre
- Interval:
- Every 14–21 days
- PHI:
- 21–30 days
Widely used on coffee leaf rust and cereal rusts; rotate with a strobilurin.
Doses shown are typical registered field rates. Always read the product label, confirm the product is registered for your crop and country, respect the pre-harvest interval (PHI), and wear the protective equipment the label specifies. PlantWatch AI provides agronomic guidance, not a legal spray recommendation.
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