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The experiments were carried out on 5 different bioproducts for control of Verticillium longisporum in oilseed rape. For in vitro trials, greenhouse trials and field trials, the bioproducts used were based on bacteria (Bacillus amyloliquefaciens, Pseudomonas veronii) and fungi (Pythium oligandrum, Trichoderma asperellum, Coniothyrium minitans). In in vitro trials, some products (based on Trichoderma asperellum) showed a 100% inhibition effect on the pathogen for a whole trial period of 45 days. The greenhouse trial showed significant differences in bioproducts effectiveness (P < 0.00723) compared to control. Three bioproducts (based on Coniothyrium minitans, Trichoderma asperellum and Pseudomonas veronii) showed a 100% inhibition effect against the pathogen. In field trials conducted in 3 locations, there were some differences in yield, which can be important for growers and practice use. The highest yield (19.1% higher than the control) was achieved with a bioproduct based on Trichoderma asperellum. In trials, it is possible to see that there are promising results that can be used for further testing.

The experiments were carried out on 5 different bioproducts for control of Verticillium longisporum in oilseed rape. For in vitro trials, greenhouse trials and field trials, the bioproducts used were based on bacteria (Bacillus amyloliquefaciens, Pseudomonas veronii) and fungi (Pythium oligandrum, Trichoderma asperellum, Coniothyrium minitans). In in vitro trials, some products (based on Trichoderma asperellum) showed a 100% inhibition effect on the pathogen for a whole trial period of 45 days. The greenhouse trial showed significant differences in bioproducts effectiveness (P < 0.00723) compared to control. Three bioproducts (based on Coniothyrium minitans, Trichoderma asperellum and Pseudomonas veronii) showed a 100% inhibition effect against the pathogen. In field trials conducted in 3 locations, there were some differences in yield, which can be important for growers and practice use. The highest yield (19.1% higher than the control) was achieved with a bioproduct based on Trichoderma asperellum. In trials, it is possible to see that there are promising results that can be used for further testing. [ABSTRACT FROM AUTHOR]

Abstract Background Phoma macdonaldii has been reported as the causal agent of black stem disease (BS) and premature ripening (PR) on sunflower. PR is considered as the most widespread and detrimental disease on sunflower in France. While genetic variability and QTL mapping for partial resistance of sunflower to stem, collar and roots attacks have been reported on plantlets in controlled conditions, this work aims to describe the genetic variability in a subset of a sunflower lines, and for the first time to map QTL involved in PR resistance evaluated in field conditions using controlled inoculation. Results An efficient and reliable method for inoculation used in field experiments induced stem base necrosis on up to 98% of all plants. A significant genetic variability for PR resistance in the field was detected among the 20 inbred lines of the core collection tested across the two years. For QTL mapping, the PR resistance evaluation was performed on two recombinant inbred lines (RIL) populations derived from the crosses XRQxPSC8 and FUxPAZ2 in two different years. QTL analyses were based on a newly developed consensus genetic map comprising 1007 non-redundant molecular markers. In each of the two RIL populations, different QTL involved in PR partial sunflower resistance were detected. The most significant QTL were detected 49 days post infection (DPI) on LG10 (LOD 7.7) and on LG7 (LOD 12.1) in the XRQxPSC8 and FUxPAZ2 RIL population, respectively. In addition, different QTL were detected on both populations for PR resistance measured between 14 and 35 DPI. In parallel, the incidence of natural attack of P. macdonaldii resulting in BS disease was recorded, showing that in these populations, the genetic of resistance to both diseases is not governed by the same factors. Conclusion This work provides the first insights on the genetic architecture of sunflower PR resistance in the field. Moreover, the separate studies of symptoms on different organs and in time series allowed the identification of a succession of genetic components involved in the sunflower resistance to PR and BS diseases caused by Phoma macdonaldii along the development of the {plant * pathogen} interaction.

Background: Phoma macdonaldii has been reported as the causal agent of black stem disease (BS) and premature ripening (PR) on sunflower. PR is considered as the most widespread and detrimental disease on sunflower in France. While genetic variability and QTL mapping for partial resistance of sunflower to stem, collar and roots attacks have been reported on plantlets in controlled conditions, this work aims to describe the genetic variability in a subset of a sunflower lines, and for the first time to map QTL involved in PR resistance evaluated in field conditions using controlled inoculation. Results: An efficient and reliable method for inoculation used in field experiments induced stem base necrosis on up to 98% of all plants. A significant genetic variability for PR resistance in the field was detected among the 20 inbred lines of the core collection tested across the two years. For QTL mapping, the PR resistance evaluation was performed on two recombinant inbred lines (RIL) populations derived from the crosses XRQxPSC8 and FUxPAZ2 in two different years. QTL analyses were based on a newly developed consensus genetic map comprising 1007 non-redundant molecular markers. In each of the two RIL populations, different QTL involved in PR partial sunflower resistance were detected. The most significant QTL were detected 49 days post infection (DPI) on LG10 (LOD 7.7) and on LG7 (LOD 12.1) in the XRQxPSC8 and FUxPAZ2 RIL population, respectively. In addition, different QTL were detected on both populations for PR resistance measured between 14 and 35 DPI. In parallel, the incidence of natural attack of P. macdonaldii resulting in BS disease was recorded, showing that in these populations, the genetic of resistance to both diseases is not governed by the same factors. Conclusion: This work provides the first insights on the genetic architecture of sunflower PR resistance in the field. Moreover, the separate studies of symptoms on different organs and in time series allowed the identification of a succession of genetic components involved in the sunflower resistance to PR and BS diseases caused by Phoma macdonaldii along the development of the {plant * pathogen} interaction. [ABSTRACT FROM AUTHOR]

Phoma macdonaldii is the causal agent of black stem disease of sunflower (Helianthus annuus L). In France, the incidence and severity of the disease increased dramatically in the early 90s and the entire sunflower cropping area is now affected. Premature ripening appeared in 1994: it is at the present time one of the most widespread and detrimental diseases of sunflower. Recent investigations confirmed that stem base girdling canker due to P. macdonaldii is the primary cause of this syndrome. Crop management and varietal susceptibility can influence significantly the incidence and severity of P. macdonaldii attacks and premature ripening. Partial resistance and presence of tissue-specific resistance genes have also been demonstrated.

Brown patches of the size from several square metres to hectares or individual dying plants appeared in otherwise green stands. Affected plants wilt and ripen sooner than healthy ones, causing them to have smaller seeds or none at all in the central part of the heads. Under extreme conditions the plants wilt and die in early summer when they are less than 50 cm high. No infective agent was found as a causal organism. Disturbed plants root only in the upper 10 cm layer of the soil, or just below the surface. Poor soil structure and aeration are supposed to be responsible for limited root development. It prevents a sufficient supply of water to the plants during the hot and dry summer months and causes them to wilt. In contrast to cereals, winter rape and some other field crops that ripen during July, sunflower grows very intensively and needs a good supply of water even towards the end of August and in the first half of September. Thus, sunflower plants rooting only in the shallow uppermost layer of the soil suffer much more than other crops from hot and dry conditions.

Abstract: In France, premature ripening (PR) is a widespread damage of a fungal disease of sunflower caused by Phoma macdonaldii. Previous results indicated that girdling canker at the stem base, caused by P. macdonaldii, was its primary cause. Previous studies have reported the influence of nitrogen and water supply on the incidence and severity of PR but an additional study was required to analyze the effect of plant density on the level of attack for a more comprehensive cultural control of PR. In a 2-year field study (2008 and 2009) in Toulouse (France), a susceptible cultivar (cv. Heliasol) artificially inoculated at star bud stage with P. macdonaldii was grown at three plant densities (4, 6.5 and 9plantsm−2) factorially combined with three N fertilization rates (0, 50/75 and 150kgNha−1) and two water regimes (irrigated and rainfed). P. macdonaldii symptoms were scored weekly to calculate the area under disease progress curve (AUDPC) and percentage of PR plants. Microclimatic conditions were monitored using thermo-hygrometers within the crop. The fraction of photosynthetically active radiation intercepted by the canopy (fPARi) and leaf area index (LAI) were measured at anthesis. Plant water status during the disease progression was characterized by crop simulation (SUNFLO) and N status at anthesis was assessed from shoot N content (Nm) analysis and N Nutrition Index (NNI) calculation. Increasing plant density resulted in a greater proportion of PR plants, and this proportion increased further when N was applied at 150kgha−1, the highest rate, and the crop was not irrigated. Despite differing canopy development, differences in microclimatic conditions between density levels were too small to explain the PR differences. However plant N concentration and diameter at stem base were closely related to PR incidence. Thin plants (grown at high density) with non-limiting N supply were the most susceptible to premature ripening. This study opens new avenues for the control of PR through crop management and emphasizes the key role of plant morphology in the development of the disease. Stem base diameter is a morphological trait that could be manipulated through crop management (plant density, N fertilization) and probably breeding in the future when developing integrated disease management systems in sunflower. [Copyright &y& Elsevier]

Abstract: Premature ripening (PR) is one of the most important diseases of sunflower in France since the 90s. Previous results indicated that girdling canker of the stem base, caused by Phoma macdonaldii was its primary cause but elucidation of critical environmental factors involved is crucial for better control of the disease. A field study was conducted in three contrasting cropping seasons (2006–2008) and investigated the effect of N fertilization (0, 75 and 150kgNha−1) and water regime (rainfed, irrigated) on two cultivars with artificial inoculation (AI) and natural infection (NI). Disease assessment was recorded weekly to calculate the area under disease progress curve (AUDPC) and the final percentage of PR plants. Data showed that high levels of N fertilization led to significantly (P <0.05) more PR than non-fertilization. Water deficit conditions were significantly (P <0.05) involved in disease severity, and AUDPC and PR were increased when dry conditions were associated with high N supply. This was true for two cultivars which differed in their susceptibility to the disease but cv. Heliasol RM was significantly (P <0.05) more affected than cv. Melody, partially resistant to PR. Despite contrasting weather patterns, these results demonstrated a clear role of crop management and environmental conditions on the incidence and severity of stem base attacks responsible for the PR syndrome. These findings suggest that sunflower crop husbandry should be adapted to minimize premature ripening induced by P. macdonaldii. [Copyright &y& Elsevier]

Molecular hybridisation analysis of a nucleic acid extract from a nectarine tree with reduced leaf production, rosetting and abnormal open growth habit has identified peach latent mosaic viroid. This is the first report of this viroid in an Australian orchard. [ABSTRACT FROM AUTHOR]