The granting of a specific off-label approval (SOLA) by the Pesticides Safety Directorate for the use of Valbon on bulb onions and shallots has offered a new option for growers to control of downy mildew.
The off-label comes in time to tackle increased disease pressure, with recent warm showery weather providing ideal conditions for spread of downy mildew. According to Andy Richardson, of the Allium and Brassica Centre, downy mildew is already present in over-wintering crops. “We will start fungicide programmes for spring drilled crops in the third week of June, so the timing of this SOLA is ideal,” he says.
The SOLA has been approved following independent trials in 2005 and 2006 by the Allium and Brassica Centre and funded by the Horticultural Development Council (HDC). Certis trials also demonstrated that Valbon has useful activity on downy mildew, as well as botrytis leaf spot.
Valbon has been used successfully on potatoes for the control of blight. It contains two active ingredients - benthiavalicarb and mancozeb - and has good translaminar and local systemic activity with both preventative and curative activity. It is rainfast within one hour.
“The addition of new active ingredients in Valbon for downy mildew control is essential,” said Richardson. “Last year, we had a 15-20 per cent loss of yield due to extremely high mildew pressure with the exceptionally wet conditions in June and July, with some growers actually running out of options for control.”
Richardson said using Valbon earlier in spray programmes due to the 28-day harvest interval. “We intend to use it for sprays two and four in our eight spray programme. Trials have shown that it provides exceptionally good results when used earlier in the programme,” he added.
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