Blight Control Strategy 2009
Controlling potato blight in 2009
Stephen Bell, College of Agriculture, Food and Rural Enterprise, Greenmount Campus,
Louise Cooke and George Little, Agri-Food and Biosciences Institute (AFBI), Newforge Lane.
Despite the wet weather in April and May, some early crops are already well advanced even though planting of maincrops has not yet been completed.
Waste potato dump management
The first case of potato blight in Northern Ireland this year has been detected on plants growing on a dump in County Down. Dumps are a major source of blight infection and good hygiene is crucial - adopt a zero tolerance approach to re-growth.
Check dumps regularly early in the season and prevent any re-growth occurring by applying a single treatment of a residual herbicide containing dichlobenil (for example Casoron G). For best results dumps should be levelled and covered with a layer of soil prior to application before any sprouts begin to grow. Dumps should then be covered with black plastic to stop light encouraging growth and checked regularly for re-growth.
- Start protecting your crop from blight whenever the first blight warning is issued or when plants meet within drills (whichever is earlier).
- Blight warnings, based on weather conditions which favour infection are issued by AFBI and CAFRE throughout the season via the radio, farming press, Blightline (028 90 38 2372) and Blight-Net. Blightline and Blight-Net will be active from the first week in June. Growers will also be alerted to the risk of blight by text messaging, contact Stephen Bell on 028 94 42 6766 to register your number.
- The first sprays should be with a product with systemic activity (for example, Epok, Fubol Gold, Merlin, Tattoo).
- Continue with a translaminar (for example, Curzate, Infinito, Invader, Revus) or protectant (for example, Electis, Ranman, Shirlan). Make no more than two applications of products such as Fubol Gold or Epok which contain phenylamides. Check the spray intervals on the label and ensure they are not exceeded. Fungicide timing and good coverage are critical, angled jet nozzles with a medium spray quality give better canopy cover at all stages of growth but particularly up to and including full canopy cover at which point the crops become more open allowing better coverage.
- The programme should be completed with at least three sprays of a product with tuber blight activity (Infinito, Ranman, Shirlan). It is critical that the crop is protected until the haulm is dead: blight can attack green leaves when the crop is senescing or even after a desiccant has been applied and this can lead to tuber infection. To reduce the risk, a fungicide should be applied with the desiccant (check product labels for approved tank-mixes) and protected from blight until the haulm is dead.
Remember to check your buyer’s protocols for a list of approved chemicals.
