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The 18th International Sunflower Conference took place in Mar del Plata, Argentina, in February, 2012. The key-points and evolutions of sunflower research were presented, in the fields of agronomy, physiology, genetics and genomics, crop protection, quality and markets. Major evolutions can be observed concerning the sequencing of sunflower genome, announced to be complete by the end of 2012, but also concerning the use of models and the progress in the studies on the interactions between varieties genetic pattern, environment and crop management practices. In crop protection aspects, the evolutions of the major pathogens, downy mildew and Orobanche cumana, have been discussed, as well as the breeding efforts for genetic resistances, or the advances concerning the herbicides tolerant varieties. Evolutions in oil quality aspects have been exposed too, such as varieties enriched in stearic acid, or tocopherols, or with low contents in saturated fatty acids.

Sclerotinia stem rot is a major disease on winter oilseed rape which causes severe yield losses twice a decade. Chemical control is usually applied at the beginning of flowering stage, every year. Because of a reduced use of chemicals expected, a biological control agent as Coniothyrium minitans could be usefull for controlling the disease. Experiments have mainly been carried out with Contans® WG, a ready-for-use formulation of C. minitans. Firstly effectiveness of C. minitans against sclerotia of Sclerotinia sclerotiorum was demonstrated. Then, its use on oilseed rape crops has been studied for several years in large size experimental plots. When it is incorporated into soil, C. minitans reduced the soil infestation by destroying sclerotia. By decreasing the soil infestation, C. minitans also reduced the primary inoculum pressure. Thus it allowed to reduce the sclerotinia risk and the disease incidence. The results are discussed according to the decision support system CETIOM in progress. Thus, a reduction of sclerotinia risk underneath a decision threshold in treated field plots could prevent any further spray of fungicides. However, it can be needed to apply fungicides which are more efficient when the disease pressure is reduced. These results contribute to integrate the use of Contans® WG in the disease management of sclerotinia stem rot of oilseed rape.

The 16th International Sunflower Conference was held from August 29th to September 2th, 2004 in Fargo, North Dakota, USA. 250 participants were present and 25 countries were represented. The leaders of the world’s main research programs on sunflower were in Fargo. Consequently, it is possible to sum up the principal orientations of world research on sunflower at present. Concerning disease resistance and pathology, downy mildew and sclerotinia are the main studied topics. Only few studies are carried out on other diseases. The main subject treated in weed control is the selection and efficiency of sunflower varieties with resistance to imidazoline herbicides, to control broomrape and other weeds. For crop production and physiology, the main programs are leaded by Argentina (interesting study about productivity and high densities) and France (Heliotest: a decision support system for nitrogen fertilization). Concerning breeding and genetics, a lot of studies were presented and confirmed a great improvement in the characterization of the genome of sunflower and other compositae. The helianthus wild species germplasm collection which is held in Ames (Iowa) was presented and described. Concerning oil composition, tocopherols and high oleic appeared as the main topics.

En France, le phoma est considéré comme la maladie la plus préoccupante du colza. Il n’existe aucune méthode de lutte à la fois efficace, rentable et respectueuse de l’environnement. Il apparaît donc nécessaire de développer la lutte intégrée de la culture contre cette maladie. Cette communication présente les résultats d’un programme de recherche visant à analyser et à modéliser les effets des systèmes de culture sur le développement de la maladie. Des pistes concrètes pour la mise en oeuvre de la lutte intégrée contre le phoma sont proposées.

Blackeg is the major disease of winter oilseed rape in France. For an efficient control of the disease several tools could be combined, but mainly plant breeding has been used to increase winter oilseed rape resistance to blackleg. A useful step was reached in the nineties, using a specific resistance gene (Rlm1). After being widely used this resistance was broken down by an increase of the virulent sub-populations of the fungus. Such a situation worried the different actors and raised the question of the promotion of a durable management of genetic resistances to Leptosphaeria. After a synthetic presentation of the state of the art in the fields of genetics of resistance, of Leptosphaeria populations and on agronomic practices able to control the pathogen, the promotion of a durable management of resistances is discussed. This target needs to precise the strategy, to improve methodologies to characterise genotypes, to promote proper agronomic practices, to follow Leptosphaeria population behaviour and to motivate economic actors.

We performed a 3‐year field survey in France to characterize the dynamics of sexual reproduction in Mycosphaerella linicola, the causal agent of pasmo, during the interepidemic period. Cohorts of fruiting bodies were sampled from linseed straw during the autumn and winter and carefully observed, focusing on pseudothecia, asci, and ascospores. A sequence of experimental steps corresponding to Koch's postulates confirmed in July 2014, for the first time in France and continental Europe, the widespread presence of the sexual stage of M. linicola in plant host tissues. The developmental dynamics of pseudothecia on straw, expressed as the change over time in the percentage of mature pseudothecia, was similar in all three years. Pseudothecia appeared in late summer, with peak maturity reached in October. A temporal shift, thought to be due to early autumn rainfall, was highlighted in one of the three years. These observations suggest that sexual reproduction plays a significant role in the epidemiology of pasmo in France. A resurgence of M. linicola infections in spring flax is thought to have occurred in recent years, due to the increase in the area under flax. The presence of the sexual stage of this pathogen probably increased the quantitative impact of residues of winter linseed (used for oil) and flax straw (left on the soil for retting and used for fibres) as an interepidemic "brown bridge". This case study highlights how certain parts of a disease cycle, in this case the sexual phase, can become crucial due to changes in production conditions. [ABSTRACT FROM AUTHOR]