Validity of Irish Potato Blight Rules

Can We Still Use ‘Irish Rules’ To Forecast Potato Late Blight Epidemics In Ireland?

Potato late blight is one of most devastating crop diseases and the most important disease of potatoes and tomatoes globally. It was one of initiators of the Irish Famine and investigations into the cause of the potato crop failure during these years have led to the scientific discipline known today as plant pathology. Since then many scientists have spent their careers investigating how Phytophthora infestans (causal agent of this disease) interacts with its host and ways to interrupt this cycle. Unfortunately, it has always found a way to fight back. Recent problems can be traced to the introduction of and emergence of new strains of pathogen in Europe during 1980’s and the early 2000s.  These population displacements can have dramatic impacts on how control is achieved, as they can lead to changes in its life cycle, increased environmental endurance and pesticide or host resistances.

Integrated Pest Management (IPM) has risen as a means of ensuring crop production is achieved in as environmentally and economically sustainable manner as possible. One of the most important components of IPM is the prediction and quantification of risk periods for agricultural pests, including diseases such as potato late blight. Irish producers use, but do not necessarily rely on warnings issued by Met Éireann – the Irish meteorological service, according to the “Irish rules” devised over 60 years ago. Re-evaluation of the blight forecasting model is needed as changes in the ‘crop – pathogen – environment’ system have taken place since they were devised.  Current practice of routine fungicide application is neither economically or environmentally sustainable. Reliable blight warning tools can help producers to target these applications to maximize control in as efficiently as possible.

Forecasting models for crop diseases are driven by environmental parameters and accuracy is dependent on the reliability of weather forecasts. Met Éireann run several weather forecast models each with their particular strengths. A new blight prediction model may feed from a combination of these weather forecast models. Potato late blight is not only an Irish problem, enormous research efforts are put into controlling this disease throughout Europe. Irish researchers are cooperating with international researchers working in the field, to combine knowledge and existing systems used in countries throughout Europe ( Ongoing field trials will help indicate the best models or combination of them to be used in Irish agroecosystem, as well as the role of resistance potato varieties. Analysis of historical weather data and disease outbreaks will also provide us with insights into patterns of disease occurrence and improving future forecasts.  As our knowledge of this ‘new potato late blight era’ improves, so too will our ability to aid Irish producers in tackling this evasive disease.

This article was submitted by Mladen Cucak. Mladen is a PhD fellow within the EPIC Project at Maynooth University & TEAGASC  and funded by the DAFM Research Stimulus Fund.
A summary of some of his work on potato blight can be found on his poster.