First outbreak of bacterial disease Curtobacterium flaccumfaciens pv. flaccumfaciens on common bean (Phaseolus vulgaris) in the Netherlands: NVWA warns of risk of import of contaminated seed
At the beginning of September 2024, the NVWA identified an outbreak of the quarantine bacterial disease Cff for the first time in three bean fields (Phaseolus vulgaris). The origin is in contaminated seed from the United States. This discovery is a coincidence. The contamination was identified following quality controls of seed, in which three different import batches tested positive for this bacterium.
In addition, several import batches of Phaseolus seed were found to be contaminated by EU member states during 2023 and 2024. The NVWA warns of a high risk and will focus on more controls to prevent new outbreaks.
Cff has been a quarantine plant disease for the EU for some time
In addition to the EU, many third countries have regulated the bacterium as a quarantine disease. The bacterium has been an important wilt disease of Phaseolus in the US for over a hundred years. The incidence varies greatly per year depending on local weather conditions and control measures. The bacterium thrives particularly well in warm, humid summers. Seed transmissibility is mainly known for Phaseolus and the bacterium can remain in seeds for over 20 years.
Which host plants?
In addition to Phaseolus species such as common bean (Phaseolus vulgaris), the bacterial disease can also occur in all other Fabaceae, including soybean (Glycine max), pea (Pisum sativum), broad bean (Vicia faba) and cowpea (Vigna unguiculata). The bacterium can survive on many different host plants, including cereals and weeds.
What measures does the NVWA take?
In the event of a discovery, the plot is demarcated, the entire crop is destroyed and at least a cultivation ban applies to all leguminous crops (Fabaceae) for the next two years, in addition to hygienic measures. Contaminated seed batches are destroyed or, in the event of interception during import, shipments can be returned.
Import controls: seed testing also important
To prevent new outbreaks, the NVWA will subject a large number of import shipments of Phaseolus to laboratory testing from the beginning of 2025. EU regulations require member states to carry out such checks in a risk-oriented manner. Please note that shipments may be put on-hold for a number of weeks pending the test results. The costs of these checks must be charged to the importers.
EU cooperation important
Other member states are increasingly vigilant for this bacterial disease and consideration is being given to harmonised import testing of at least Phaseolus seeds by all EU member states. Based on the experiences of these import controls, it may be decided to have structural laboratory testing take place in countries of origin.