Researchers of Wageningen UR have created a computer model that shows the effects of weather on the distribution of Phytophthora infestans spores. As a result, the number of sprayings required to control potato blight can be reduced by 20 to 30%. An article on this new computer model will soon be published in the journal Agricultural and Forest Meteorology.
Predicting whether a potato field can become infected by the fungus-like pathogen is now based on the weather during the past week and the weather forecast. The pathogen thrives with humid, cloudy weather. But the risk of infection also depends on the presence of spores in the vicinity. Unfortunately, neither farmers nor researchers know the exact location of all sources of infection.
Several years ago, PhD student Pete Skelsey developed a model at the Meteorology and Air Quality Group with which he could quantify the spatial distribution of Phytophthora, without knowing the sources of infection. During strong winds with heavy turbulence, the spores can spread across great distances. During sunny weather or if they spend a long time suspended in the atmosphere, the spores are killed natural UV radiation. Consequently, the capacity of the atmosphere to disseminate Phytophthora spores varies enormously.
The researchers linked Skelsey's dissemination model to their knowledge of the potato crop, the epidemiology of the pathogen and the weather forecast; taken together, these factors predict the risk of infection. This led to a decision-support model that can advise farmers about whether to spray or not.
‘We tested the model for two years at an experimental farm, where the farmers often have problems with Phytophthora’, says researcher Dr Geert Kessel of the Plant Sciences Group. ‘In this region, they spray 10 to 15 times per year. Due to our advice, the farmers were able to reduce the number of sprayings by 20 to 30%, which is three fewer sprayings per year on average.’ During the field trials, decisions to not spray never led to an unforeseen infection with the pathogen.
Next year, field trials will be conducted at five test locations throughout the Netherlands. If the results from these trials are also positive, the model will be ready for practice. The researchers linked the model to the decision-support program Simcast, but it can also operate with other decision-support software, says Kessel. Commercial providers of such systems were therefore included in the project from the start.
The research is part of the Phytophthora 'Umbrella Plan', a framework of cooperation between Wageningen UR and the sector organisation for agriculture (LTO Nederland) with the aim of reducing the environmental load from potato production. Kessel also advises arable farmers about using resistant potato varieties. ‘The fully resistant potato does not yet exist, but some varieties are more resistant than others, which means you can use smaller amounts of crop protection chemicals. By combining this approach with our disease dissemination model, the farmer can spray 40 to 60% less. This means he can farm in an environmentally-friendly fashion while saving a lot of money.’ / Albert Sikkema
The above article was written by the editorial staff of Resource, the weekly newspaper for Wageningen University and Research Centre. For more information, contact the press and science information officer of Wageningen UR, e-mail: pers.communicatie@wur or the editorial staff of Resource, e-mail: resource@wur.nl. See the archived articles at http://www.resource-online.nl