Adjuvant helps to boost new triazole
By Mike Abram
USING SPECIFIC adjuvants could help growers maximise returns from new Bayer CropScience triazole fungicide Proline, say two leading distribution companies.
Both Agrovista and UAP have found disease control benefits from using adjuvants with Proline (prothioconazole), which translates into extra yield for growers.
Agrovista”s Transcend adjuvant has given positive yield benefits in 22 out of 24 trials, says technical manager Mark Palmer. “The mean response is 0.22t/ha.”
For an input typically costing just 2.50/ha that represents a good return, he says. “Particularly when you think the whole industry accepts 0.4t/ha from strobilurins.”
The key to its success is the combination of organosilicon wetter, which enhances coverage on the leaf surface, and modified vegetable oil, which helps get the triazole into the leaf, he says. “The latter seems crucial. We”ve tested some other adj<00AD>uvants which just improve coverage and have got negative responses.
“It is clear you need the combination but the key is getting prothioconazole into the leaf. Once in the plant it has additional activity, which you are unlocking.”
Unlike the Agrovista adjuvant, which it claims improves foliar disease control, UAP has concentrated on improving Proline”s eyespot activity with its adjuvant mixes.
The firm has tested two adjuvants – Designer, a mix of organosilicon wetter and latex sticker, and Abacus, an esterified rape oil plus surfactants. “Both have given enhanced control of eyespot and extra yield,” says technical director Chris Bean.
“Eyespot activity by adding adjuvant to 0.4 litres/ha Proline is taken close to the level achieved by 0.6 litres/ha.” The lower rate is more likely to be typical on-farm, he believes. “Using an adjuvant is a way of achieving better yields and efficacy from that rate.”
Most of Agrovista”s dose work has been done at the 0.4 litres/ha rate, with its trials showing a similar pattern of 0.4 litres/ha plus adjuvant equalling activity from a 0.5 litres/ha rate of Proline.
But Dr Palmer stresses growers should select the triazole dose to control disease, and then enhance activity by adding the adjuvant, rather than use the adjuvant to cut doses.
Using Transcend could allow growers to cut water volumes, he adds. “With less labour, but larger areas on farms to cover, timeliness can be a crucial issue.”
Reducing water volumes to 100 litres/ha from 200 litres/ha can increase work rates by up to a third, he calculates. “But it can come at the cost of disease control through reduced spray penetration.”
Previous work has shown that adding Transcend to products such as Opus (epoxiconazole) and Opp<00AD>onent (epoxiconazole + pyraclostrobin + kresoxim-methyl) brings efficacy levels back up to those achieved by 200 litres/ha water volumes, he says. “Our initial work with prothioconazole suggests a similar result.”
But growers should be careful with lower water volumes when app<00AD>lying multiple mixes, he cautions. “There is a scorch issue. With multiple mixes it is wise to push water volumes back up to 200 litres/ha.”