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Corn pests, diseases and growing guide for Jamaica

What goes wrong with corn in Jamaican conditions, how to recognise it early, and what the crop needs at each stage. 4 common problems covered.

Growing conditions at a glance

Plant family	Poaceae
Target soil pH	5.8 – 7
Seedling stage	Transplant to day 14
Vegetative stage	To day 45
Flowering stage	To day 65
Harvest	Single harvest

Common corn pests and diseases

Fall Armyworm

A devastating caterpillar pest that aggressively consumes the whorl of corn plants.

Signs to look for

Massive ragged holes in corn whorl leaves
Large amounts of sawdust-like frass in the whorl
Caterpillar with a distinct inverted 'Y' on its head

What to do: Apply a product whose label lists caterpillars, such as Xentari or Dipel DF (Bt), Match, Phoenix or Indicarb 14.5, directly into the whorl. Spray early in the morning or late evening.

Corn Earworm

Caterpillars that burrow directly into the tip of the corn ear, ruining the kernels.

Signs to look for

Silks are chewed off
Hole at the tip of the ear with frass
Damage to the top kernels

What to do: Apply oil and Bt directly to the corn silks. Spray Pyrethroids when silks first emerge.

Corn Smut

A fungal disease of corn characterized by massive, swollen galls on ears and stalks.

Signs to look for

Large, swollen, grayish-white galls on ears or stalks
Galls eventually burst releasing black powdery spores

What to do: Cut out and destroy galls before they burst. Avoid physical injury to plants.

Southern Rust

An aggressive rust disease affecting corn in hot, humid climates.

Signs to look for

Small, orange-to-light brown circular pustules
Pustules primarily on upper leaf surface
Rapid yellowing and death of leaves

What to do: Plant resistant hybrids. Apply a fungicide whose label lists rust, such as Bellis 38 WG, at the first sign of disease.

Feeding corn by growth stage

Stage	Nutrition	Why
Seedling	Balanced Starter (e.g. 14-28-14)	Apply starter fertilizer slightly below and to the side of the seed.
Vegetative	High Nitrogen (e.g. Urea or SOA)	Side-dress with high nitrogen at knee-high and waist-high stages (V4-V8).
Flowering	Potassium	Tasseling and silking are critical water and potassium windows.
Fruiting	Potassium	Grain fill requires sustained moisture.

Questions growers ask

What are the most common corn pests and diseases in Jamaica?

The problems growers report most often are Fall Armyworm, Corn Earworm, Corn Smut, Southern Rust. Each one is described above with the symptoms to look for and the recommended response.

What soil pH does corn need?

Corn performs best in soil with a pH between 5.8 and 7. Outside that range nutrients become progressively less available to the plant even when they are present in the soil.

How long does corn take to grow?

Counting from transplant, the seedling stage runs to about day 14, vegetative growth to about day 45, and flowering to about day 65, after which the crop moves into fruiting or bulking.

Track it in the app

PlantArmor keeps your corn spray records, input costs and harvest weights in one place, and the app works with no signal while you are out in the field. Free to use.

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Other crop guides

Pest descriptions and treatments above come from the same reference library the PlantArmor app uses in the field. Pesticide registrations and permitted uses change — always read the current product label and observe the stated rate, re-entry period and pre-harvest interval.