A powerful new 3-D interactive model of potato crop growth and the factors that influence the onset of Alternaria could provide growers and agronomists with predictions of disease impact on crop yields, and help govern appropriate fungicide programmes.

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Developed by Wageningen University crop physiologist, Ioannis Baltzakis, in association with Syngenta, it is one of the first uses for novel digital Functional Structural Plant Modelling techniques.

Armed with results and risk factor analysis from Syngenta’s UK Alternaria trials, allied to tracking of the various Alternaria pathogen species by NIAB, the complex computer generated model is building a better picture of potential disease outbreaks, and their likely outcomes.

Demonstrating the model at The British Potato Event BP2107, David Wilson, Syngenta Area Manager and potato specialist for the eastern counties, highlighted better understanding of Alternaria and the conditions for its development would be key for more proactive agronomy decisions.

“This is a significant step forward and has enabled us to continue progressing our earlier work with NIAB,” he reported. “That initial research has identified the pattern of Alternaria species spread. But it is only when you add in the other factors for the spore spread and disease development that you can make informed decisions of if, or what, to spray, and when.”

Mr Wilson reported that the use of in crop monitoring and innovative drone technology, to identify areas of crop stress - such as less available nitrogen or irrigation issues – could pinpoint the effects of Alternaria on any given crop.

Syngenta trials over the past season have looked at susceptible varieties grown under a range of conditions to express stress effects, along with combinations of Amphore Plus and Amistar fungicide treatments.   

Ioannis Baltzakis reported the model marries 3-D plant architecture with the processes that govern growth. “The model will allow us to predict potential losses and, potentially, indicate the best time to control the disease.

“If, for example, Alternaria is coming into the crop very late in the season, it maybe that there is no economic advantage to controlling the pathogen,” he advised. “However, earlier incidences do need to be targeted at the optimum time to prevent early leaf senescence - and the effects on yield and quality.

“With the model you can simulate all those different timings and see the different results.”

David Wilson added that successive years of Alternaria leaf tissue testing by NIAB has revealed the A. alternata strain to typically be the first to appear, typically starting in late June.

He advocated growers should start their planned Alternaria programmes with Amphore Plus, with the aim to take advantage of the product’s high difenoconazole content to load up protection in the plant at the start of the risk period.

At BP2017 he demonstrated how difenconazole had been proven to be effective against inhibiting mycelial growth and development of both strains of the disease, but especially A. alternata, compared to alternative active ingredients.

“As the season progresses and if Alternaria risk persists, growers can switch to Amistar, targeted specifically at the later occurring, but typically more damaging, A. solani strain of the pathogen,” he added.

“Growers now have a full season programme available to tackle Alternaria. The key is to have protection in place before infection breaks out – where the predictive model could prove extremely valuable,” concluded David.