Foliar feeding of maize: at which stage and how

By Nikola Mojsa, MSc in Agricultural Engineering

When to feed maize through the leaf

A foliar feed is added when there is a specific reason for it: after stress (disease, drought) or when a micronutrient is short, because maize then falls behind in growth and pollination is poorer (AgroPortal). The timing is therefore set by the state of the crop, not the calendar, and the agronomist always confirms the stage and the product.

The stages come from AgroPortal (in Croatian); the heights up to which a tractor can pass through the crop are based on the experience of our agronomist Nikola.

Foliar feeding should be done early in the morning or late in the afternoon to avoid leaf damage (same source). Above 24 °C the stomata of some species close and uptake falls (Agroklub), which is why we don't work in the worst of the heat.

Zinc and other micronutrients in maize

Unlike zinc, phosphorus and potassium go on at primary tillage on most soils, because they carry no risk of leaching (AgroPortal).

Maize tolerates only low concentrations of solution (AgroPortal). Which nutrient goes on your field, at what rate and at which stage is for the agronomist to decide, ideally from a soil analysis and the symptoms on the plant. We explain the basics in Foliar feeding: what it is and when to do it.

Foliar feeding of maize that is too tall for a tractor

A tractor sprayer can pass through maize while the crop is up to 1 to 1.5 m tall. Once the rows have closed, the wheels break plants, and the loss in the wheel tracks comes to 5 to 6% of the crop, as our agronomist Nikola regularly sees in the field. The drone flies about 3 metres above the crop and follows its height, so it feeds maize of 2 metres or more just as well as maize of 1 metre.

The downdraught from the rotors drives fine droplets right down to the lower leaves, so the solution covers the whole leaf mass. The drone sprays 15 to 20 litres of water per hectare, while a tractor uses 200 to 300 litres (AgriNova). The same amount of nutrient in less water gives a stronger solution, so the product and concentration are set by the label and your agronomist, who checks that the product can be applied in a low water volume.

After rain, only the access road to the field needs to dry, and if there is tarmac all the way to the field we work the same day, even after heavy rain. If the wind goes above 3 to 5 m/s, we pause and carry on once it drops.

Feeding maize and spraying insecticide against corn borer in one pass

The first generation of European corn borer is controlled in early to mid-June and the second in early August (Agrosava). That is exactly when maize grows too tall for a tractor, so the same field is often waiting for both an insecticide and a feed. Whether the two products can be mixed is stated on the label. If that isn't clear, the expert advice is to apply them separately (for example, protection today and feeding 48 hours later) or to jar-test the mix first (AgriNova).

Protection always comes first: the insecticide timing is set by the moth flight and the hatching of the larvae, while feeding can wait a few days. How the corn borer flight is monitored is explained in European corn borer: when and how to spray.

If we do three treatments on the same field in a season (for example corn borer, fungicide and feeding), you get 5% off; five or more treatments get 10% off.

Price of feeding maize by drone

Foliar feeding of maize costs the same as spraying: €25 per hectare up to 20 ha, €22 from 20 to 100 ha and €20 above 100 ha. You supply the product and the water. Travel within 50 km of Opovo is free, and new clients ordering at least 10 ha get the first hectare free on their first order.

Worked example: 40 ha, 22 km from Opovo, first order. 40 ha × €22 = €880, minus €22 for the free first hectare = €858 in total. Check the price for your location in the calculator, and read all about the service on the foliar feeding by drone page.