The fungicide Invader has new label recommendations for the control of downy mildew (Peronospora destructor) in bulb onions, garlic and shallots and the reduction of white tip (Phytophthora porri) in leeks, a welcome addition to the dwindling options that Allium growers have to control diseases and maintain quality.
Simon Townsend of BASF explains that Invader used to have a SOLA for these uses, but these have now been made full on-label recommendations. "Allium growers need a range of fungicides to use within their programme in order to control damaging diseases as well as managing resistance. Invader has performed consistently well on all strains of onion downy mildew, including metalaxyl-resistant strains. In trials, it reduced levels of downy mildew from over 55% of leaf plant affected down to 10%. A new label recommendation for Invader which contains two actives with different modes of action will be welcomed, especially when other fungicides such as straight chlorothalonil and some chlorothalonil formulations will be going this year."
Simon also points out that the recommended label rate of 2.5 kg/ha of Invader for bulb onions, shallots and garlic delivers a full dose of both actives, equivalent to 187.5 gms ai of dimethomorph per hectare and 1667 gms a.i. of mancozeb per hectare. "This is more than other mancozeb-containing fungicides and means more robust control."
"Invader also has a very useful 14 day pre-harvest interval for bulb onions, shallots and garlic, whereas all other onion fungicides containing mancozeb have an interval twice as long, 28 days."
In leeks its pre-harvest interval is 21 days.
Invader should be applied in a protectant programme starting before the appearance of disease symptoms or when local monitoring and forecasting indicates a high risk of infection. "In outdoor bulb onions, shallots and garlic it can be applied up to a maximum total dose of 10 kgs of product/ha, equivalent to 4 applications at its recommended dose of 2.5 kgs/ha and in leeks up to 6 kgs of product per hectare, equivalent to 3 applications at its recommended dose of 2 kgs/ha," reminds Simon Townsend.
Invader can be sprayed in sequence with Signum to add robust downy mildew control to the programme.
Signum (boscalid and pyraclostrobin) has a SOLA for use in onions for the control of Sclerotinia, Leaf Spot (Alternaria porri), Cladosporium allii-cepae and rusts (Puccinia allii). Signum also has a good level of back up activity on downy mildew but not to the same degree as the downy mildew specialist fungicide Invader.
