Yield Loss and Integrated Disease Control of Rhizoctonia solani AG2-1 Using Seed Treatment and Sowing Rate of Oilseed Rape

Rhizoctonia solani anastomosis group (AG) 2-1 is an ubiquitous soilborne pathogen causing severe damping-off of oilseed rape (OSR). In the absence of varietal resistance to AG2-1, there are limited methods for integrated disease management. The objectives of these field studies were to quantify yield losses due to AG2-1 and to determine the effectiveness of integrated control using sedaxane, fludioxonil, and metalaxyl-M applied as seed treatment on two OSR genotypes at a sowing rate of 40 (low) or 80 (high) seeds m^-2. Crop assessments of green area index (GAI), vigor, and cabbage stem flea beetle (CSFB) Psylliodes chrysocephala damage were carried out at GS16, while pathogen DNA in soil was quantified using real-time PCR at GS32. Yield and seed weight losses of 41 and 18%, respectively, were associated with reduced establishment, GAI, vigor, and delayed development and flowering of OSR. Seed treatment reduced AG2-1 DNA in soil by 80%, resulting in a 94, 16, and 64% increase of establishment, thousand seed weight (TSW), and yield, respectively. Seed treatment also mitigated the effects of AG2-1 on delaying plant development, resulting in increased uniformity of crop flowering. OSR plants infected with AG2-1 suffered 27% more damage by the CSFB, indicating positive pathogen-pest interaction at the expense of the OSR host. Optimum control of AG2-1 infection was achieved by integrating low sowing rate and seed treatment. However, under dual pest and pathogen attack, high sowing rates should be combined with the use of seed treatment to mitigate seedling death and delayed development caused by AG2-1 and CSFB damage.

Modification of the existing maximum residue level for sedaxane in potatoes

In accordance with Article 6 of Regulation (EC) No 396/2005, the applicant Syngenta France SAS submitted a request to the competent national authority in France to modify the existing maximum residue level (MRL) for the active substance sedaxane in potatoes. The data submitted in support of the request were found to be sufficient to derive an MRL proposal for potatoes. Adequate analytical methods for enforcement are available to control the residues of sedaxane on the commodity under consideration at the validated limit of quantification (LOQ) of 0.01 mg/kg. Based on the risk assessment results, EFSA concluded that the short‐term and long‐term intake of residues resulting from the use of sedaxane according to the intended agricultural practice is unlikely to present a risk to consumer health.

SDHI Fungicide Toxicity and Associated Adverse Outcome Pathways: What Can Zebrafish Tell Us?

Succinate dehydrogenase inhibitor (SDHI) fungicides are increasingly used in agriculture to combat molds and fungi, two major threats to both food supply and public health. However, the essential requirement for the succinate dehydrogenase (SDH) complex—the molecular target of SDHIs—in energy metabolism for almost all extant eukaryotes and the lack of species specificity of these fungicides raise concerns about their toxicity toward off-target organisms and, more generally, toward the environment. Herein we review the current knowledge on the toxicity toward zebrafish (Brachydanio rerio) of nine commonly used SDHI fungicides: bixafen, boscalid, fluxapyroxad, flutolanil, isoflucypram, isopyrazam, penthiopyrad, sedaxane, and thifluzamide. The results indicate that these SDHIs cause multiple adverse effects in embryos, larvae/juveniles, and/or adults, sometimes at developmentally relevant concentrations. Adverse effects include developmental toxicity, cardiovascular abnormalities, liver and kidney damage, oxidative stress, energy deficits, changes in metabolism, microcephaly, axon growth defects, apoptosis, and transcriptome changes, suggesting that glycometabolism deficit, oxidative stress, and apoptosis are critical in the toxicity of most of these SDHIs. However, other adverse outcome pathways, possibly involving unsuspected molecular targets, are also suggested. Lastly, we note that because of their recent arrival on the market, the number of studies addressing the toxicity of these compounds is still scant, emphasizing the need to further investigate the toxicity of all SDHIs currently used and to identify their adverse effects and associated modes of action, both alone and in combination with other pesticides.

Review of the existing maximum residue levels for sedaxane according to Article 12 of Regulation (EC) No 396/2005

According to Article 12 of Regulation (EC) No 396/2005, EFSA has reviewed the maximum residue levels (MRLs) currently established at European level for the pesticide active substance sedaxane. To assess the occurrence of sedaxane residues in plants, processed commodities, rotational crops and livestock, EFSA considered the conclusions derived in the framework of Commission Regulation (EU) No 188/2011, the MRLs established by the Codex Alimentarius Commission as well as the European authorisations reported by Member States (including the supporting residues data). Based on the assessment of the available data, MRL proposals were derived and a consumer risk assessment was carried out.