Field vegetable fungicide Rudis (prothioconazole) has gained a new approval for control of Sclerotinia, Alternaria and powdery mildew in carrots.
Nathan Whitehouse, Bayer CropScience product manager for field vegetable crops, says the tzt technology of prothioconazole delivers broad-spectrum disease control and physiological effects that previously have only been available from strobilurin containing fungicides.
“Using Rudis in alternation with strobilurin-based fungicides, such as Nativo 75WG (trifloxystrobin + tebuconazole), will enable carrot growers to optimise crop health and keep their disease control programmes within FRAC resistance management guidelines for strobilurin fungicides,” he says.
“In trials, Rudis has demonstrated the strongest curative action of all fungicides against Sclerotinia infection of carrot foliage. It also provides protection against Alternaria and powdery mildew on a par with Nativo 75WG, the class-leading strobilurin-based fungicide.”
In the development of this new use, Bayer assessed a range of control programmes alternating between strobilurin and non-strobilurin fungicides under high disease pressure from Sclerotinia.
Alternating between Nativo and Rudis achieved the best protection of foliage and root crowns and outperformed programmes alternating between Amistar Top (azoxystrobin + difenoconazole) and tebuconazole or Signum (pyraclostrobin + boscalid) and tebuconazole. This was reflected in significantly greater yields and root weights after storage.
Bayer recommend the first application of Rudis should ideally be made before disease establishes in the crop and prior to canopy closure in June to July. Nathan Whitehouse explains; “This is particularly important for Sclerotinia control, to ensure foliage is adequately protected as the micro-climate underneath becomes optimal for ascospore release from soil germinating apothecia.”
Following with Nativo 75WG and subsequently alternating between these two fungicides in a programme will utilise the strongest chemistry available against all foliar diseases in carrots he claims.
As for other crops on the label, maximum individual dose is 0.4 L/ha, three applications per crop are permitted and latest time of application is 21 days before harvest. One restriction specific to carrots is that it can only be used on crops that will be mechanically harvested.
Growers holding stock purchased prior to this label extension must obtain the new approval from the CRD website before application to carrots.