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Blackgrass Prime Clavering 2022 Untreated

Powering-Up with propaquizafop

Although spring is moving rapidly towards us, temperatures across the UK have remained fairly volatile in recent weeks, with spells of relatively mild weather interspersed with periods of significantly cooler, often below-freezing conditions.
Blackgrass Prime Clavering 2022 Untreated

With that in mind, it is worth considering how the use of adjuvants can help to power-up the efficacy of herbicide actives such as propaquizafop in a cold and dry season.

ADAMA’s straight propaquizafop herbicide, FALCON® (100 g/L propaquizafop), provides excellent control of volunteer cereals, ryegrass, common couch and sterile brome, and can contribute to the control of black-grass as part of a herbicide management strategy where mixtures and sequences of herbicides with alternative modes of action are used.

However, the efficacy of active ingredients such as this – and many other ACC-ase herbicides – depends on the prevailing growing conditions and in particular the temperature. For example, propaquizafop works best at 15-25oC.

In situations where these lofty temperatures aren’t reached (e.g. during a cold, dry spring), an oil-based adjuvant can help to improve the efficacy of propaquizafop: as the image below shows, FALCON® comprehensively controls winter wheat when applied in glass-house conditions at temperatures in the range of 15-24oC (2nd and 3rd pots from left). 

However, at lower temperatures (in this case overnight at 5oC for 14 hours, followed by 10 hours at an ambient temperature), the efficacy of the propaquizafop is delayed (2nd pot from right) due to a reduced rate of movement of the herbicide into weeds and particularly to the part of the target plants on which they act (notably the meristematic tissues of the leaves).

Focal Point Preview Image

Focal Point Preview Image

The addition of an adjuvant mitigates this effect (far right), by enabling more of the active ingredient to enter and move within weeds, with adjuvants of all major classes (mineral oils, surfactants and high surfactant oil concentrates) all improving control (see graph below).

Focal Point Preview Image

The simple message is therefore to consider not only which weeds you need to control and which active ingredient to use, but also how and when to apply your chosen herbicide.

FALCON® best practice

  1. Optimal application on volunteer cereals in OSR is by the 3-4 leaf stage (BBCH 11-14)
  2. Efficacy depends on growing conditions, with optimum control achieved at 15-25oC
  3. An adjuvant can improve herbicide efficacy in cold and dry conditions

FALCON® (100 g/L propaquizafop)is a foliar acting selective herbicide with systemic activity on a wide range of grass weeds and volunteers for use in oilseed rape, sugar beet, potatoes and a range of vegetables.