White blister (also known as white rust) is not a true rust and is not well controlled by rust fungicides. It is hard to control, especially if it becomes systemic within the plant. Cultural controls such as paddock selection, removal of host weed species and good plant nutrition may reduce the risk of infection.

FAR Arable Update VS4 White blister of radish seed crops outlines three trials set up in 2016/17 to better understand the development and spread of white blister of radish seed crops. It can be found on the FAR website.

Key points

• It was possible to detect the presence of white blister oospores in most seed lines;
• In a pot trial, disease development and severity did not appear to be influenced by oospore loading on the seed surface and all lines became infected;
• White blister may infect the internal seed structures and act like an endophyte. Therefore the disease is seedborne, infecting the seedling plants when conditions are suitable;
• Ridomil Gold® MZ WG remains active against white blister and forms the base for an effective control programme, with useful additions from Pristine®, Amistar® and Seguris Flexi®;
• It is important not to rely on one fungicide group (e.g. Ridimol) as this could increase the risk of resistance developing;
• Increased white blister disease control was strongly related to increased seed yield.

Source: FAR