Jan/Feb 2021: Trace belt preparation post paraquat: Mission Impossible?

By Roger Poole, TIPWG Chair

As we imagined, we have been fielding numerous emails and calls about how to tackle the coming fire season’s tracer belt preparation without using paraquat. For many, this normally daunting task, made more challenging by the past summer’s excessive rainfall in some areas and resultant vegetation growth, now feels like “mission impossible”.

Yes, there are many glyphosate products registered for fire break preparation on our APL. Many of these, if used in a correctly calibrated mechanized unit, can create the burndown effect that minimizes the impact on the plants roots and therefore reduces the risk of soil erosion. However, there are still huge swathes of fire break preparation to be done on hilly inaccessible terrain, where manual operations are the only option and achieving a chemical scorch or burn down to prevent glyphosate from being taken up by the plants root system is extremely difficult, if not impossible. As a result, TIPWG cannot recommend its use.

So where to now? No paraquat and ideally, no glyphosate too.

This season will see the renewed use of Glufosinate-ammonium, an active ingredient whose mode of action as stated on the label is: “A non-selective, non-residual, partly systemic contact herbicide”. Reading through the various labels on Agri-Intel the recommended application rate is between 5-7.5lt’s per hectare applied in 200-300 litres of water per hectare in the summer rainfall region. For any vegetation that is taller than 50cm, the volume of water recommend is 800 litres per hectare. As we all know, the majority of the vegetation on the tracer belts is taller than 50cm’s, so a higher rate is needed to ensure good penetration and coverage of the mixture. Remember: for optimal results, the vegetation must be actively growing so now is the time to apply Glufosinate-ammonium.

However, Glufosinate-ammonium does not come without concerns.

Industry members have raised the concern that Glufosinate-ammonium could be more systemic than a contact herbicide if incorrectly applied. This would mean that erosion on steep terrain is highly likely. The high volume of water recommended brings additional transport costs, especially when supplying additional water to applicators on difficult terrain. Most concerning is that the time from application to burning is unknown. Worst case, this could result in a) the vegetation still being too green to burn resulting in an unsafe break to complete the main break, or b) if left too long greening up, resulting in the vegetation not burning at all and been frosted off after the first frosts, again resulting in an unsafe area to prepare the main break. Then there is the cost per litre, which at an application rate of between 5-7.5 litres per hectare could be in the vicinity of R 1 000.00 to R 1 500.00 per hectare.

Less ‘Mission Impossible’ more ‘Mission Unfavorable’.

It is clear there are alternatives to paraquat, all be it less favourable and potentially less effective. To improve the situation, there are several good practices’ that will ensure whichever you choose is used in the most efficient and therefore effective fashion:

  • read the label, this can never be over-emphasised and if in doubt,
  • contact your agri-chemical distributor
  • calibrations are set to label specifications and done in the area where the tracer belt is to be treated to ensure it is done accurately
  • use of trained seasoned applicators so that the application is done timeously and correctly
  • know your weed spectrum to ensure the correct application rate is used, and money is saved
  • regularly service your application equipment and check your nozzles. Worn nozzles can cause unnecessary expense either by over or under applying the product.
/ Pesticide interest piece