Recent advances on the characterization and control of sunflower soilborne pathogens under climate change conditions

Abstract

The control of soilborne crop pathogens is conditioned by the limited management options due to difficult access to active infection courts and to restrictions in the use of synthetic pesticides in Europe. For most soilborne sunflower pathogens, an effective management relies on genetic resistance which is, however, hindered by new pathogen populations (new races). Special emphasis is thus put on updated monitoring and characterization of pathogens and on the enlargement of the set of tools for disease management. Concerning characterization, advances on the population structure of Verticillium dahliae affecting sunflower by means of genetic, molecular and pathogenic approaches are presented. Also in relation to increases of sunflower wilt diseases recently observed, the fungus Cadophora malorum has been identified in Russia and reported as a new pathogen of this crop. Third, new races of Plasmopara halstedii (sunflower downy mildew), have been identified in Spain and Portugal. Most of them have a high virulence, since they overcome several genes for resistance. With regard to alternatives for disease control, entomopathogenic fungi (EF) constitute a novel tool. Used for years in Integrated Pest Management strategies due to their efficacy in controlling insect pests affecting crops, new ecological roles of these fungi have recently been reported. The EF species Beauveria bassiana and Metarhizium brunneum have been assessed by their in vitro effect against V. dahliae and C. malorum by our research group. Our results suggest that antibiosis and/or competition for ecological niche are operating in some EF-pathogen interactions. In summary, pathogen characterization is essential for genetic resistance for worldwide environments of sunflower production. Moreover, the security of sunflower yield and profitability is dependent not only on effective genetic resistance, but also on additional new control options that can be included in successful strategies of sunflower disease management.

Biofumigation to protect oilseed crops: focus on management of soilborne fungi of sunflower

“…Soilborne pathogens can coexist in the soil (Raaijmakers et al, 2009), and their heterogeneous distribution makes monitoring them costly and usually ineffective (Matthiessen and Kirkegaard, 2006). For many oilseed diseases, genetic resistance is one of the most effective protection methods, but it breaks down frequently due to the appearance of new virulent strains, as observed for sunflower diseases (Vear, 2016;Debaeke et al, 2017b;Molinero-Ruiz, 2019). To reduce the pressure of soilborne pathogens, farmers used to fumigate vegetable and ornamental crops intensively with methyl bromide (Hoffmann and Malkomes, 1974;Duniway, 2002;Martin, 2003).…”

“…The most damaging and widespread fungal diseases are downy mildew (Plasmopara halstedii), phoma black stem (Phoma macdonaldii), phomopsis stem canker (Phomopsis helianthi), white mold (Sclerotinia sclerotiorum) and Verticillium wilt (Verticillium dahliae) (Seassau, 2010;Vear, 2016;Debaeke et al, 2017b), most of which are soilborne pathogens (P. halstedii, S. sclerotiorum, V. dahliae). More recently, Cadophora malorum has been reported as a new soilborne fungus of sunflower (Martín-Sanz et al, 2018;Molinero-Ruiz, 2019). In the context of climate change, Macrophomina phaseolina could be favored by ground dryness and temperatures of 28-30°C (Šárová et al, 2003).…”

Ayçiçeği mildiyösü etmeni Plasmopara halstedii (Farl.) Berl. & de Toni’nin Türkiye’deki ırklarının tespiti ve bazı ticari ayçiçeği çeşitlerinin bu ırklara karşı reaksiyonlarının belirlenmesi

“…Recently, race determination with nine differentials has been found insufficient for some races and a new set comprising 15 lines have been adopted. Mostly new races over 7 digits have increased especially after the introduction of new resistant cultivars (Molinero-Ruiz 2018, Sedlarova et al 2016, Shindrova 2010.…”

Evidence of soil‐located competition as the cause of the reduction of sunflower verticillium wilt by entomopathogenic fungi

“…dahliae isolates used were previously characterized in a multidisciplinary study (Martin‐Sanz et al ., 2018b) and were selected on the basis of their different geographical origin and pathogenic race (Garcia‐Carneros et al ., 2014; Martin‐Sanz et al ., 2018b). C. helianthi isolates were selected from the plant pathogen culture collection in the Field Crop Disease Laboratory at the Institute for Sustainable Agriculture from CSIC (IAS‐CSIC) in Cordoba, Spain (Molinero‐Ruiz, 2019).…”

“…In the case of sunflower, V . dahliae is one of the most important pathogens and is widespread in the USA, Argentina, Europe (Pegg and Brady, 2002; Gulya et al ., 2019; Molinero‐Ruiz, 2019), and some regions of Canada (Erreguerena et al ., 2019). The only control measure available in sunflower is genetic resistance (Pegg and Brady, 2002), which was first reported in this crop in Manitoba in 1957 (Putt, 1958) and was found to be race specific and based on single genes (Fick and Zimmer, 1974).…”