Bayer CropScience’s fungicide Infinito (fluopicolide + propamocarb) has been granted an EAMU for use on bulb onions.
This is the result of an application by the HDC at the request of British Onions following exceptionally high downy mildew pressure last year. AB Agronomy’s Andy Richardson says the warm April and May last season, with just enough showers and nighttime dews while plants were growing rapidly, made for a perfect storm of downy mildew.
“We threw everything we had at it and still struggled. Normally we see the first signs of downy mildew in over-wintered crops at the end of May to early June, but last year it came in a month earlier and then conditions were ideal for it to move on fast to spring sets and spring drilled crops. This year’s warming up the same way and the majority of overwintered crops currently have a level of downy mildew in them,” he warns.
AB Agronomy build disease control programmes around Unicur (fluoxastrobin + prothioconazole) + mancozeb and slot other fungicides, mainly co-formulations of a strobilurin and mancozeb, in between the four permitted Unicur treatments. The Infinito EAMU permits one application at 1.6 L/ha which Andy expects will be an essential addition to disease control programmes. Should the season begin with high disease risk he advises using it earlier rather than later.
Bayer product manager for fruit and vegetables, Claire Matthewman, says Infinito has a proven track record against oomycete diseases. “In potatoes it’s one of the three Euroblight premier league products and is unique in combing effectiveness against foliar and tuber blight with antisporulant activity. For bulb onion growers it offers a different mode of action to any other fungicide in the downy mildew armoury and has a 7-day pre-harvest interval which could be advantageous
in a wet season.”
One restriction in the EAMU is that; ‘to protect groundwater do not apply this or any other product containing fluopicolide at a rate of more than 400 g/ha in any three year period’. Andy Richardson Infinito EAMU for bulb onions thinks that in practice this should not be an issue, as growers like to keep onions and potatoes at least three years apart in rotations to minimise potato volunteers in onion crops.