REACH THE FULL POTENTIAL

Each crop protection product has an inherent potential. With a herbicide like glyphosate, it is to achieve acceptable weed control at the label recommended rate. Although this is an in-built potential, the efficacy varies as external factors take a toll on glyphosate. Therefore, the weed control is sometimes much poorer than the potential of the herbicide. One solution to this problem is to apply the herbicide under conditions where external factors don’t play a major role. However, it is impossible to always wait for the perfect conditions, therefore adjuvants are used to decrease the influence of these external factors.

WHAT CAN GO WRONG?

The first aspect that influences glyphosate is the loss of ultra-fine spray droplets because of drift and evaporation, limiting coverage. The second efficacy limiting aspect is droplet bounce and reduced droplet spreading, both of which decrease coverage. The third aspect is the naturally occurring cations in hard and brackish spray water. These cations bind to the glyphosate during spray droplet drying and limit the absorption and weed control. The fourth aspect is poor absorption through the waxy layers on the leaf surface, reducing both the rate and amount of glyphosate uptake. Absorption is also affected by the low humidity conditions so prevalent in certain parts of South Africa. Therefore, glyphosate faces various challenges, all of which reduce weed control. Fortunately, there are adjuvants that address most of these problems.

HOW CAN ADJUVANTS HELP?

Drift and coverage are addressed by using the correct deposition agent. This ensures that more droplets reach the target and increase coverage. Surfactants decrease the surface tension of the spray solution, ensuring less droplet bounce and moderate spreading of spray droplets. Please adhere to the label recommendations on whether a tank-mix surfactant is required. With the use of ammonium sulphate adjuvants, the cations in hard and brackish water are bound on the leaf surface before they can form poorly absorbed glyphosate complexes. The absorption of glyphosate is further enhanced by humectants that keep the spray droplet deposit moist and conducive for absorption, long after application. A further role of surfactants is to help move glyphosate through the waxy layers on the leaf surface to ensure more absorption. Adjuvant rate and use may vary according to label recommendations and conditions. However, always use the label recommended adjuvants to help glyphosate to reach its potential.

VILLA's STANCE

Adjuvants help to decrease the effect of external factors on glyphosate. These adjuvants are found in separate products or in multi-component adjuvants. When using a multi-component adjuvant, please make sure that it contains enough of each active ingredient to do the job properly. Remember that adjuvants also have limitations and should not be used as a licence to apply glyphosate under extremely adverse conditions. Please always use the label as a guideline. Contact your Villa agronomist for more information about adjuvants and water quality.