Why new maize seed treatments require extra safety measures

Maize growers switching to alternative bird-repelling seed treatments this spring following the Mesurol ban are being advised to observe extra health precautions when handling seed.

Respiratory health warnings accompany the new alternative seed treatments containing ziram (Initio and Korit), replacing methiocarb (Mesurol), which was banned on 3 January.

This is according to Neil Groom, Maize Growers Association council member and technical director at Grainseed, who urges growers to check and comply with advice on chemical hazard labels.

See also: Why drilling maize deeper and later could be future trend 

Speaking to Farmers Weekly, he says some seed had been treated with Mesurol and will still be planted this year.

However, some farms will be using ziram products Initio and Korit. See safety information for Korit (PDF).

These treatments, like Mesurol, are toxic, but in addition can be fatal and can cause respiratory irritation.

Additionally, Force 20 (telfluthrin) is also available as an insecticide working on strong vapour pressure, which also claims to repel birds from seedlings. 

“For years, operators will be used to working without masks, which now needs to change. Even if the product does not contain ziram, it’s worth taking precautions,” says Mr Groom. 

What should I wear to work with Ziram-treated seed?

  • Nitrile gloves (374-3)
  • Polyester/cotton workwear overalls
  • Respiratory protection mask (FFP3)

Source: LG Seeds safety recommendation

Cultural controls

As seed treatment options narrow down to brands based on the ziram active, independent agronomist Craig Green of CMG Agronomy says cultural controls should not be forgotten.

“There are seed treatments with ziram that will repel birds, but they may not be the full answer,” Mr Green says.

“The big thing farmers can do is to roll seed-beds that are dry enough, drill into warmer seed-beds, and drill slightly deeper to protect seeds from birds.”

Seed treatments containing ziram should be used with care, and full personal protective equipment should be worn when handling the seed, Mr Green says.

He adds that loose or spilled seed should be covered or picked up so birds aren’t attracted to fields.

Four options to help limit bird damage

  1. Delay drilling The longer you wait to drill, the warmer it is likely to be. Consider delaying drilling for one week so seeds swell, chit and germinate as soon as possible, reducing the time rooks and other birds have to peck at them. Temperature: 8C for lighter soils, 12C for heavy soils. 
  2. Drill deeper Normal drill depths of 3-5cm could be increased to 5-7cm or more. However, the deeper you plant seeds, the more energy will be required for them to germinate and break through the surface. 
  3. Roll for consolidation Rolling in dry conditions could be a way to firm up the surface to make it harder for birds to peck through. It is important not to roll soils in damp conditions, as you may create a hard cap that is detrimental to maize establishment. Make sure tyre pressure is optimal to avoid causing compacted wheel marks in the maize crop.
  4. Try biostimulants Buy seed with a biostimulant dressing or talk to your agronomist about applying biostimulants at emergence. These are amino acids that drive energy production for root systems to grow bigger, making it more difficult for birds to lever out young plants at the first true leaf stage. This will also improve scavenging for nutrients and water at a later stage.

Source: Craig Green, CMG Agronomy, Norfolk