Article taken from Agronomist & Arable Farmer, July 2017.
Much of the debate about glyphosate has been based around the safety of co-formulants used to enhance the properties of the active ingredient.
Of these, wetting agents and emulsifiers derived from animal fats, known as polyethoxylated tallow amines, have come under particular scrutiny.
In October 2015, a European Food Safety Authority (EFSA) statement concluded that in comparison to glyphosate, 'a significant toxicity of POE-tallow amines was observed'.
A regulation was introduced amending the approval of glyphosate formulations, so that only products without tallow amines could be approved.
In the UK, the sale and distribution of glyphosate formulated with tallow amines expired on June 30, 2017, with a final use date for farmers and growers of June 30, 2018.
Surprisingly, tallow amines are still permitted to be included in many adjuvant and water conditioners, sometimes at higher concentrations than in glyphosate formulations, says Agrovista technical manager Mark Palmer.
""To us, it makes little sense to use these products as they do the opposite of what the regulation is trying to achieve, and could pose problems further down the line with the legislators.""
Agrovista's Discovery Range of adjuvants and water conditioners, including the multifunctional adjuvant Companion Gold, use more modern chemistry and have never contained tallow amines, he adds.
""This is easy enough to check," says Dr Palmer. ""Look at section 3 of the product safety data sheet and see if CAS number 61791-26-2 is listed as a hazardous ingredient.""
Agrovista Select trials are comparing the application and efficacy of the new 360g/litre glyphosate formulations coming onto the market with old tallow amine-containing formulations.
Initial replicated trials carried out at Agrovista's heavy land Project Lamport site, in Northamptonshire, examined the destruction of cover crops and black-grass prior to drilling spring wheat.
Treatments were applied during stem extension to put pressure on the formulations to pull out differences between treatments, as this is a difficult timing to get high levels of control, says Dr Palmer.
A tallow amine and tallow amine-free formulation were applied at 1.5 litres/ha (54og/ha), and both treatments gave a high level of efficacy on control of susceptible species, such as black oat and wheat.
However, control of black-grass was significantly reduced with the new tallow amine-free formulation (figure 1).
""Although both reduced the amount of biomass in comparison with the untreated, there was significantly more weed left in the plots treated with the new formulation, and this was black-grass," says Dr Palmer. ""That's not good news.""
The same trial also examined the benefit of tank-mixing Companion Gold with the new formulations. ""Companion Gold is a tallow amine-free multifunctional adjuvant and pod sealant ideally suited to glyphosate," he comments. ""It combines drift reduction, antiÂfoam, pH buffering and water conditioning with improved rainfastness and efficacy.""
The addition of Companion Gold significantly improved the level of black-grass control, halving the amount of biomass remaining in comparison to the tallow amine-free formulation applied alone (figure 2).
The first trials were applied by hand-held boom at 3.6kph. ""Additional trials assessed efficacy and spray application technique using our specialist spray application trials sprayers at 100 litres/ha at 14.4kph to mimic commercial practice," says Dr Palmer.
A range of glyphosate formulations were also applied at ear emergence of the blackÂgrass. Levels of control were higher, as anticipated, exceeding 90%.
""However, there were differences between the formulations and adding Companion Gold gave significant improvements in efficacy," says Dr Palmer.
Aerial agronomy developments
Rapid developments in technology and processing software mean relatively cheap and simple drones can now carry out increasingly complex agronomic tasks.
Drones costing less than £1,000 can measure crop parameters such as establishment, biomass and presence of weeds and diseases, and a few more pounds will deliver the capability to assess plant counts.
""Relatively recently, you would have needed a high Âspec drone costing about £10,000 to map weeds quickly and efficiently," says Lewis McKerrow, head of precision technology at Agrovista.
""Now, a good quality hobby drone can produce similar results with standard visual camera gear for a fraction of the price.""
The development of flight planner apps for tablets and smartphones make it very easy for relatively unskilled operators to carry out these flights, he says. However, anyone using a drone for commercial purposes must obtain a PfCO (Permission for Commercial Operations).
A typical crop-scanning flight will produce l-2GB of data. Flying several times across fields produces masses of data.
To process this mountain of information, Agrovista has recently launched a quick Âturnaround data-processing service for growers using their own drones, using Map!T Pro software to create field zone maps.
These maps can be overlaid with other data sources, such as soil nutrient maps, to create variable rate maps for a range of inputs. Agrovista offers input recommendations as an additional service.
For farmers who want to use drone technology without the capital outlay, Agrovista also offers a commercial drone service, featuring a range of flight packages carried out by the company's operators.
""The ultimate aim is to use data from several seasons to optimise crop establishment and minimise the need for rectifying treatments," says Mr McKerrow.
Yield prediction models are also in the pipeline.