Some growers have had the opportunity to use the best SDHI in their vegetable crop for a couple of years now by incorporating the protectant and translaminar fungicide Perseus into their disease control programme. Perseus contains 75 g/litre of fluxapyroxad (Xemium) and 50 g/litre of difenconazole formulated as a suspension concentrate. Fluxapyroxad is a highly effective SDHI fungicide with broad spectrum activity and difenconazole is a well-known triazole fungicide with excellent selectivity in speciality crops. It has nine recommended crops on its label – broccoli/calabrese, Brussels sprouts, cabbage, cauliflower, carrot, potato, vining pea and outdoor and protected lettuce.
The end of 2019 saw the addition of 16 new crops via the EAMU system. These crops are beans with pods, Dwarf French beans, edible podded peas, runner beans, celeriac, horseradish, Jerusalem artichoke, parsnip, radish, red beet, swede, turnip, courgette, gherkin, pumpkin and squash. “As growers plan their disease control programmes for the year, they should be considering inclusion of this new and very effective option,” says Robert Storer of BASF.
Ringspot is the most common and widespread disease at the moment in brassicas. In development trials, in cabbages where the untreated suffered 18% ringspot, Perseus gave the best treatment reducing it to just 8%. In Brussels sprouts, the untreated had 14.7% severity of Mycosphaerella (ringspot) but Perseus reduced this to 1.1% and in other trials the sprout crop had 12.5% Alternaria, with Perseus reducing this to 0.9%. In cabbages with 22% Alternaria, this fungicide reduced disease to less than 1%. Perseus has demonstrated superior control compared with other fungicides in many trials.
In carrots for powdery mildew for example, the untreated area had 15% severity of attack but Perseus reduced this to 4%. For Alternariacontrol in carrots the untreated had 24% disease severity but Perseus reduced this to 5%, better than the other competitive fungicides. “Reporting on all these trials demonstrates the excellent efficacy of Perseus, its broad-spectrum activity and its superior activity,” says Robert.
Robert explains that Perseus has activity on Powdery Mildew, Alternaria (Light and Dark Leaf Spot), Mycosphaerella (ringspot) and Sclerotinia, so most of the key diseases in vegetables. In terms of mobility, Perseus has excellent contact, translaminar activity plus apical activity and movement to protect new growth. It also shows good redistribution after rewetting and one hour’s rainfastness.
Rob points out that the combination of the two complementary active ingredients leads to excellent efficacy as well as inbuilt resistance management, meaning maximum yield, quality and profitability for growers. “Its rapid uptake and mobility results in excellent efficacy, local systemicity and rainfastness, maximising the spray window. Its long lasting protectant activity means robust field performance so Perseus can be relied upon as a key part of the spray programme. It is good news that Perseus can now be used in many more crop situations.”
Three applications of Perseus can be made to brassicas, 1 to outdoor lettuce, 1 to vining peas, 4 to potatoes and 2 to carrots and protected lettuce. It has a harvest interval of 3 days for potatoes, 7 days for carrots and 14 days for vining peas and lettuce. Its dose rates are 0.6 l/ha for powdery mildew control, 1 l/ha for Alternaria and Mycosphaerella and 2 l/ha for Sclerotinia.
It should be alternated in a programme with other fungicides with an alternative mode of action as part of an anti-resistance strategy.
For any EAMU, growers should obtain a copy of the notice of approval via the Chemicals Regulation Directorate (CRD) web site, ADAS offices or NFU.