Published on 05/02/2021
And there’s a good reason for that – they are really important physical characteristics (along with adhesion). If the herbicide doesn’t stay on the plant after application, penetrate the outer tissue, and move freely from there to the roots, all before the plant locks down its own defensive mechanism, your farmers might as well not bother spraying in the first place.
But have you ever wondered exactly how uptake and translocation are measured? For one of New Zealand’s best-known glyphosate suppliers, the answer comes down to some very fiddly, precise chemical science. “It’s actually quite a process, quantifying the speed of uptake and translocation for a herbicide like CRUCIAL,” says Nufarm technical specialist Cynthia Christie.
It’s also a job best left to an expert, in this instance Dr Robin Gaskin of Plant Protection Chemistry NZ, who recently retired after many years of providing highly specialised analytical studies and research to agrichemical and adjuvant manufacturers worldwide. She and her team at Rotorua did the uptake and translocation work on CRUCIAL before the advanced new glyphosate was launched to the NZ market last year, and Cynthia Christie says without their expertise Nufarm would not have been able to provide the hard data it has on these key performance attributes.
So how did they do it? “It’s quite interesting. That sort of laboratory study uses glyphosate labelled with the radioactive compound carbon 14, which shows up on autoradiograph imaging equipment. The concept is similar to the use of barium in human x-rays.”
For the Nufarm tests, tiny doses of CRUCIAL with the 14C marker were applied in solution to the leaves of ryegrass plants grown out specifically for this purpose. “The researchers have to simulate a normal commercial application, so they apply very small amounts of solution using a tiny micro pipette. Then the treated plants are left for a range of different intervals, from 30 minutes to 24 hours, depending on the trial protocol.”
After the designated time period has elapsed, the tiny drop (or what’s left of it) is washed off the treated leaf, and the amount of radioactivity remaining on the surface of the plant is measured. Then the treated leaf, the leaf opposite which is untreated, and the roots of each plant are cut up, processed, and also measured for the amount of radioactivity present.
“And that’s how we can present data and images showing exactly where the glyphosate molecule has travelled through the plant over what period of time,” Cynthia Christie says. A similar process is used to track uptake of CRUCIAL with Pulse Penetrant, supporting Nufarm’s 15 minute rainfastness guarantee.
Gathering such data is neither cheap nor fast, but provides confidence for both resellers and end-users. “It’s part of our product stewardship, making sure our formulations do what we say they will do,” Christie says.
For more detail contact your Nufarm territory manager.