7 April 2000

Maize survey reveals main grower issues

MAIZE growers put quality first when selecting varieties, rate black nightshade as their biggest weed problem, and recognise that 10-40 days after emergence is a key time for weed control, according to a survey released last week by seed and chemical suppliers NK and Novartis.

The survey also found that producers with less than 20ha (50 acres) of maize last year planned to increase the area grown, while those with 60ha (150 acres) of maize are either making no change in the area grown, or are reducing it.

NKs Nigel Padbury says most respondents grow maize to replace concentrates, with dry matter yield coming a close second reason for growing the crop.

Aiming to replace concentrates fitted well with producers choosing quality as their first requirement in a variety, he told a Press conference. "They are looking for good digestibility and starch content."

But the second factor in determining variety choice – earliness – was over-rated, believed Mr Padbury. "Growers need to be aware of variety maturity, but some are still choosing very early varieties unnecessarily, and are sacrificing yield, particularly in areas south of the Thames valley."

But growing the crop, and keeping it weed-free, preoccupied many respondents, said Novartis Tom Robinson. Both keeping the crop weed-free long enough for good crop establishment and controlling weeds in dry conditions proved a challenge. But, he added, producers were aware of the key timing for weed control – between 10 and 40 days post crop emergence.

While he urged producers to ensure they used the most appropriate herbicide program for their conditions, he added that sprayer nozzle selection was also worth considering. "Maize leaves droop and shade weeds from spray applications. If sprays are going to hit the right target then some horizontal movement must be driven into the spray by producing fine droplets that move into the canopy on air turbulence.

"The ideal nozzle is a conventional fan jet, no larger than F110-04, 110í, for optimum coverage and weed control. Not all spray contractors will know about nozzle selection for maize, so it is worth asking them about it."

He added that spray booms were also often run too high; they should be 40cm (16in) above the crop. &#42