Resistant grey mould is an increasing problem for Danish strawberry growers

Grey mould that is resistant to the few approved pesticides in Danish strawberry production, is an increasing problem for Danish strawberry growers. A new project will explore if the resistant grey mould is already in the plants when imported.

2018.10.01 | Camilla Mathiesen

The theory is that the plants are already infected with resistant grey mould fungus on arrival in Denmark.

Grey mould is the most common disease for strawberry growers and can destroy a large part of the crop, both when the fruit is still on the plant and also after harvest, ie. during storage and at consumers. 

Danish growers typically get their plants delivered from Germany, the Netherlands or Poland, and it is likely that the resistant grey mould is already in the plants when imported. This theory is now being studied in the Sprayless project, funded by the Ministry of Food and the Environment’s Green Development and Demonstration Programme (GUDP).

Project Leader, Senior Researcher Marianne Bertelsen from the Department of Food Science, Aarhus University, explains:

- The theory is that the plants are already infected with resistant grey mould fungus on arrival in Denmark. Spraying against grey mould favours the resistant strains of grey mould and facilitates spreading because the non-resistant strains are killed by the sprays.     

How much - and how fast?   

Although it does not help to spray more, that is what the growers often do, because they don’t know they have resistant grey mould in their fields.     

-  We believe that, in this situation, it is actually better to spray less so that the non-resistant variants of grey mould are not replaced by resistant ones, Marianne Bertelsen says.

This year, imported plants have been planted at the Department of Food Science research fields at Aarslev, Denmark and both plants and fruit are being analyzed for resistant grey mould.

Next year, trials will be carried out at several growers properties, with a focus on how much and how fast the resistant grey mould spreads.

One of the aims of the project is to clarify the optimal use of spraying against resistant grey mould, and exploit alternatives in an attempt to reduce the number and amount of spraying while ensuring that the spraying is effective.     


Further information

The project Sprayless has been granted 5 million DKK from the Ministry of Food and the Environment’s Green Development and Demonstration Programme (GUDP).

Participants include: Aarhus University, GartneriRådgivningen (HortiAdvice Scandinavia), I/S Lykkesholm (strawberry grower), Per Nielsen (strawberry grower), Lindflora ApS og SW Horto A/S. 

Read more about the project (in Danish)

Contact
Senior researcher Marianne Bertelsen
Department of Food Science, AU
Mail: marianne.bertelsen@food.au.dk
Phone: 8715 8328  

Food, DCA