18 April 1997

Maize tactics in dry

MAIZE drilling depths and weed control may have to be adjusted if the dry weather continues.

Ideally, maize should be drilled at as shallow a depth as practicable to ensure good germination, says ADAS consultant Phil Humphrey.

But the seed must have moisture and in dry conditions maize should be drilled into the moisture layer up to an absolute maximum depth of 10cm (4in), he says.

"Where the moisture level is below this depth the seed would be better drilled to about 1-2in so the seed could capitalise on any rainfall immediately."

Weed control may also have to be adjusted because atrazine also needs moisture before it becomes active. He explains that in dry conditions incorporation of atrazine is generally recommended and should be within the top 5cm (2in) of the soil. This will place the chemical at a level where weeds germinate and ensure it is closer to the surface should rainfall occur.

"Alternatively atrazine could be applied as a contact herbicide when maize is at the two- to four-leaf stage to control weeds. At this stage bromoxynil, also a contact herbicide, could be tank mixed with atrazine to improve weed control or mixed with a mineral oil adjuvant to improve leaf coverage," he says.

"Where conditions are very dry it could be better to delay drilling. Drilling into a dry site could cause patchy emergence, making accurate weed control more difficult." &#42