The EU ban on chlorothalonil fungicides from May 20 next poses a significant threat to short term winter wheat and barley production in Ireland, said Teagasc, Oak Park, researcher Steven Kildea at last week’s National Tillage Conference.
He said these multi-site fungicides had become key in control programmes over the past two decades for Septoria tritici blotch in winter wheat, and Ramularia leaf spot in winter and spring barley.
For septoria, chlorothalonil sprays were initially used to delay development and spread of fungicide resistance, and more recently for control of this fungal disease.
For Ramularia, these sprays have been essential for control almost since the recognition of the disease in the late 1990s and early 2000s.
Chlorothalonil sprays have also been used against chocolate spot of winter and spring beans.
Mr Kildea said the weather will fundamentally dictate the levels of disease that may develop.
But strategies can be put in place to buffer this to a certain extent.
These will be different for each crop and disease.
For Septoria, these include growing resistant varieties, delayed sowing, and canopy architecture.
For Ramularia, minimising stresses on the cereal plant during the growing season is fundamental to delay development of the disease.
However, the epidemiologies of both diseases make the ideal strategies often difficult to achieve without adversely impacting potential yields.