Lettuce growers are being advised to adopt a more integrated approach to tackle the increasingly severe issues of Bremia affecting leaf quality, shelf life and overall marketable yield. Latest information released by the International Bremia Evaluation Board (IBEB) has verified three official new races BL:29, 30 and 31 – which pose a significant risk and highlight the danger of reliance on varietal resistance alone.
Syngenta Salad Crop Specialist, Christopher Lees, reported that varietal resistance remained a key attribute to minimise the impact of Bremia infection, but that growers must be vigilant for new disease isolates and implement an integrated approach using fungicides to combat the threat.
“The rapid evolution in Bremia races is obviously of concern to lettuce producers and drives home the need to support genetic resistance with a robust crop protection programme. We are fortunate in having a range of effective fungicides, such as Revus,” advised Mr Lees.
In trials under extreme Bremia lactucae (Downy Mildew) pressure last summer, Revus was the most effective of the fungicides tested in terms of general crop health, leaf area affected by the disease and overall ground cover. Despite the high disease pressure and being in an area heavily cropped with lettuce, the Revus treated crop achieved 87% ground cover at maturity, compared to just 50% in the untreated.
“It clearly confirmed the agronomic importance of utilising a strong crop protection programme alongside varietal resistance,” reported Mr Lees. He advocated that growers should incorporate Revus within a programme containing a range of chemistry, with the short seven-day harvest interval of Revus making it particularly well placed as the last application in a programme.
Mr Lees added that Syngenta has a strong portfolio of commercial lettuce varieties with excellent physiological attributes and strong resistance packages against Bremia. Furthermore, exciting new varieties of even stronger genetic material, with excellent agronomic traits and an improved range of resistances, were set to be launched over the coming season.
He believed the strategy of incorporating genetics and crop protection products as an Integrated Crop Solution, would ensure effective long-term sustainability for lettuce production.
Mr Lees highlighted that Syngenta is the only manufacturer that can help to address both the genetic and crop protection components of growers’ Bremia strategies. “We are able to offer truly integrated programmes, to ensure robust protection now and into the future."
