SLU news

Herd immunity in food crops for increased food safety

Published: 25 November 2022
A person is holding a tray of strawberry plants. Photo.

Can heard immunity in food crops be achieved through speckled use of resistant cultivars, biocontrol and chemical fungicides? This will be investigated in a new research project at SLU financed by Formas.

Strawberry is the economically most important berry in Sweden, but great losses are caused each year by a grey mold fungus. Several different fungicides (chemical and biological) are used against grey mold, but unfortunately this harmful fungus has developed resistance to almost all plant protection products. The most used fungicide in Sweden has two active substances - but despite this, resistance is starting to develop in grey mold fungi all over Europe.

– It is extremely important to deal with this problem. In our new project, we are investigating a concept based on the herd immunity that can occur both when using chemical or biological fungicides. The model system is strawberry infected by Botrytis cinerea, a fungus that causes grey mold, says Johan Stenberg.

Herd immunity provide economic savings and lower environmental risk

Herd immunity is a form of indirect protection from disease that occurs when a sufficient percentage of a population becomes immune to infection through, for example, vaccination thereby reducing the likelihood of infection for individuals who lack immunity. If the project is successful, lower amounts of plant protection products can be used, leading to economic savings and reduced environmental risk.

– In addition, the evolution of counter-resistance will be delayed, thus enabling prolonged durability of plant protection products and resistant cultivars. The cropping security as well as the economic and ecological sustainability for farmers, concludes Johan.


The project will be carried out by a PhD student that will be supervised by Johan Stenberg, Erik Andersson, Mudassir Iqbal and Åsa Lankinen. In total, 3 MSEK has been granted by Formas - a Swedish Research Council for Sustainable Development.

Apply for the PhD position: PhD student in Biology: epidemiology and eco-evolutionary biology