Adjuvants extra bonuses
Adjuvants extra bonuses
By Edward Long
ADJUVANTS can allow reduced-rate herbicide applications, cutting costs without compromising efficiency. But they offer more than just cash savings, says Dick Neale of Wisbech-based HL Hutchinson.
"Adjuvants are not suitable for all products or all crops. But where they can be used they reduce spray drift, improve penetration where water is reduced, and boost activity of other tank-mix partners."
While some herbicides stipulate that adjuvants must be used, many others, such as fenoxaprop products, also benefit where reduced rates are used. Adjuvant contents in formulations are designed for full-rate applications, explains Mr Neale.
"When rates are reduced, adding extra adjuvant can bring efficiency almost back to full-rate level," he says.
In cereals, increasing resistance to herbicides among the main grass weeds means any angle to improve herbicide efficacy must be grasped.
"Virtually all blackgrass, and ryegrass samples we test have metabolic resistance to IPU and fops, and increasingly dims as well. So a mix-and-match policy is needed with actives, with rates kept high and an effective adjuvant added."
For grasses, esterified vegetable oil additives, such as Phase II, are better than mineral oils, and less harsh on the crop, he adds.
Growers planning to plant spring crops should exploit the opportunity to clean up seed-beds before drilling with glyphosate. Adding an adjuvant such as Sprite means generic formulations may be used, but there is no need for adjuvant with the pre-formulated Sting or Roundup Biactive, he points out.
Later, most growers are likely to use a sulfonylurea such as Quantum, Ally, Boxer, GP928 or Harmony M. All these can be used with an adjuvant such as Torpedo, a penetrant and wetter, but nothing should be mixed with carfentrazone products, he stresses.
"If grass weeds are a problem the options include Grasp or Tigress Ultra, but the latter has no approval for adjuvant," he adds.
In sugar beet the switch from emulsifiable to suspension concentrates, aimed at cutting solvent pressures on the environment, could see a return of vegetable oil partners for herbicides to soften the impact on crop and claw back efficiency of frequent low-dose treatments, suggests Mr Neale.
"New formulations lend themselves even more to oil additives than before. But growers must be aware of growth stage cut-offs, most can be used until the six-leaf stage."
One crop where adjuvants cannot be used is peas, he continues.
"Adjuvants must not be used with pea herbicides as they affect leaf wax, making plants susceptible to herbicide," he warns.
[BOX]
ADJUVANT ANGLES
* Reduce rates not efficacy.
* Less drift, more penetration.
* Boost overall tank-mix?
* Read labels before use.
[as panel?]
Many winter cereals have a larger mat of weeds than usual this year so herbicide rates should be jacked-up, suggests Mr Neale. "Bigger weeds need more herbicide and adjuvants cannot replace all the active." However, esterified vegetable oil additives will boost the effectiveness of Boxer (florasulam) and Lexus (flupyrsulfuron-methyl). In contrast, with carfentrazone-ethyl (as in Platform S or Ally Express), which gives rapid knockdown of large weeds, no adjuvant should be added, he advises.
Herbicide rates
Many winter cereals have a larger mat of weeds than usual this year so herbicide rates should be "jacked-up", suggests Mr Neale. "Bigger weeds need more herbicide and adjuvants cannot replace all the active." However, esterified vegetable oil additives will boost the effectiveness of Boxer (florasulam) and Lexus (flupyrsulfuron-methyl). In contrast, with carfentrazone-ethyl (as in Platform S or Ally Express) which gives rapid knockdown of large weeds, no adjuvant should be added, he advises.
ADJUVANT ANGLES
• Reduce rates not efficacy.
• Less drift, more penetration.
• Boost overall tank-mix?
• Read labels before use.