When should you water your crop? Do you need to apply extra boron?

The persistent drought is raising questions among maize growers. When should I water my crop? Do I need to give my crop extra boron? The way things are right now there doesn’t seem to be any reason for panic.

The first signs of the effects of drought in maize crops are being reported, for example curling leaves. Jos Groot Koerkamp, sales manager at Limagrain, says growers need not worry too much yet. “The curling leaves are the plant’s first reaction to protect itself against a shortage of moisture. The plants curl their leaves to minimise transpiration. You’ll see the leaves stretched out again the next morning. It’s only when leaves are still curled up in the morning that your crop is suffering from insufficient water.”

Maize specialist Siebrand Veltman of VisscherHolland sees no immediate reason for worrying either. “Right now the crops don’t need that much moisture. Until the plants really start growing they need around 1.5 to 2 millimetres of water a day. When the rows begin to close and the crops start growing faster they will need 3 to 4 millimetres. If there is then insufficient moisture for them their growth will stagnate. The plants will also tend to start flowering earlier.”

According to Groot Koerkamp and Veltman there’s little sense in watering maize crops at this stage already. Groot Koerkamp: “One of the few times in a crop’s development when irrigation is important is just before flowering, around mid-July. Then the plants really need plenty of moisture to produce well-filled cobs.”

Foliar fertilisation with boron

Another question concerns the availability of boron, which is lower than usual because of the drought. That’s because boron is mobile in the moisture in the soil. It is an important element for maize plants on account of the role it plays in transporting nutrients and moisture through the plant.
So should you be giving your crop extra boron via foliar fertilisation? As far as Veltman is concerned, livestock farmers who have already given their crop sufficient boron need not yet worry. “Most important is for sufficient boron to be available just before the plants start forming cobs.”

Groot Koerkamp fully agrees and warns farmers not to rashly spray their crops with boron. “First check how much boron is actually available in the soil and consider how much your crop needs. Most standard maize fertilisers contain sufficient boron. If you nevertheless see dying growing points, which are a symptom of boron deficiency, you could apply extra boron, optionally combined with a foliar fungicide. But don’t spray your crop’s foliage on a sunny day or else you may end up with scorched leaves.”