Research is under way to control fusarium of garlic.

For some years now, garlic producers in France have been suffering losses due to fusarium. During storage, the bulbs turn brown, rot and are therefore unusable as seed or for consumption. The peculiarity of this fungal disease is that it does not show early signs in the field, making it difficult to predict and control. Although present in many countries, little is currently known about the causes of this disease other than that it is caused by a fungus of the Fusarium genus. For example, it is not known which species is responsible for the symptoms, where it is located (in the soil? the air? rotating plants, etc.?) and how it infects garlic.

Mobilisation of the sector and initial experiments.

Since 2015, the garlic sector has been working to find solutions. To set up specific experiments and to compensate trainees and fixed-term contracts, a source of funding was essential. The members of Prosemail (the association of French producers of certified garlic and shallot seedlings) voted unanimously to double the membership fees. French Interprofessional Organisation for Seeds and Plants also agreed to make a contribution: a “Voluntary Contribution Made Obligatory” (CVRO) of one cent per kg, levied on sales of certified seedlings, was put in place in 2018. As a result, every producer who buys certified garlic plants contributes to all Prosemail’s experimental programmes, particularly the one on fusarium.
Prosemail in partnership with FNAMS has set up treatment trials with certain active ingredients targeting rust but they have had no effect on fusarium. As a reminder, there is currently no marketing authorisation against fusarium of garlic. Experiments have shown that cold storage delays the onset of symptoms on bulblets. However, it does not treat the cause of the disease. In order to protect garlic effectively and permanently from fusarium, it became necessary to undertake more fundamental research, drawing lessons from the initial experiments. So the sector, with Prosemail, the Alinéa cooperative and the Lautrec Pink Garlic Syndicate in the front line, decided to join forces and call on researchers from INRAE (formerly INRA) to build a thesis project together.

Dynamics of garlic fusarium research

This thesis, whose scientific direction is provided by the Plant Pathology Unit of INRAE Avignon, is financed by a CIFRE grant and by Prosemail, Alinéa and the Lautrec Pink Garlic Syndicate. The objectives are (i) to determine the identity of the Fusarium(s) responsible for the symptoms of garlic rot in France, (ii) to understand how the fungus enters the tissues of the bulblets, and (iii) to develop a method for early detection of the fungus. The work of the PhD student has already shown the presence of Fusarium proliferatum in French garlic(1). Subsequent results will be the subject of a future column.
Parallel to the thesis, two other projects on fusarium of garlic, in which INRAE and Prosemail are participating, are under way (funded by INRAE and Casdar). These projects, which testify to the dynamism of research on the subject, also involve experimental stations (notably CEFEL), chambers of agriculture, technical institutes (ACTA, CTIFL) as well as ACTA, CNRS and FiBL. These projects aim to understand the conditions that lead to the appearance of garlic rot symptoms and to identify levers to limit epidemics. Good research work takes time and, as they are validated, the results of these projects should shed much light on fusarium of garlic and open up new avenues for the development of methods to protect garlic.

(1 ) The publication can be accessed at this address: https://apsjournals.apsnet.org/doi/full/10.1094/PDIS-06-18-0962-PDN

Photo caption (© INRAE)
Damage occurs during storage. What is the fungus responsible for the symptoms and how does it infect garlic?