Ronald Zeun

Biological activity of sedaxane---a novel broad-spectrum fungicide for seed treatment.

BACKGROUND Sedaxane is a new broad-spectrum seed treatment fungicide developed by Syngenta Crop Protection for control of seed- and soil-borne diseases in a broad range of crops. Its physicochemical properties and activity spectrum have been optimised for use as a seed treatment providing both local and systemic protection of the seed and roots of target crops. RESULTS Sedaxane inhibits respiration by binding to the succinate dehydrogenase complex in the fungal mitochondrium. Its activity spectrum covers seed-borne fungi such as Ustilago nuda, Tilletia caries, Monographella nivalis and Pyrenophora graminea, as well as the soil-borne fungi Rhizoctonia solani, R. cerealis and Typhula incarnata. Under greenhouse conditions, sedaxane showed high levels and consistent protection against U. nuda, P. graminea and Rhizoctonia spp. Under field conditions, efficacy against Rhizoctonia spp. resulted in increased yield compared with the untreated check. Efficacy against snow mould has been shown under very high disease pressure conditions. The combination of sedaxane plus fludioxonil against snow mould can provide resistance management for sustainable use. CONCLUSIONS The broad spectrum and high level of activity in combination with excellent crop tolerance allow the use of sedaxane as a seed treatment in a wide variety of crops. It is a potential tool for precautionary resistance management when combined with other fungicides, especially against pathogens showing a potential for resistance development, such as M. nivalis.

N-Sulfonyl Amino Acid Amides, a Novel Class of Compounds with Fungicidal Activity [1]

Novel types of oomycete fungicides have been designed and prepared. The synthetic approach to these N-sulfonyl amino acid amides is outlined. Bioassays demonstrate their high efficacy against important plant diseases likePhytophthora infestans (tomato and potato late blight) and Plasmopara viticola (grape downy mildew). Structure-activity relationship studies are discussed.

Benefits of Chemical Seed Treatments on Crop Yield and Quality

Agriculturists have been treating seeds to protect them from pathogens and pests for centuries, even before the nature of plant diseases was understood. Today, the use of seed treatments is a highly sophisticated strategy that has evolved into a very valuable, effective, and environmentally friendly component of agricultural production practices. Chemical seed treatments can be used to achieve a variety of benefits, including: improved emergence, through protection from seedborne pathogens and soilborne pathogens and insects; prevention of seed transmission of seedborne pathogens; protection of above-ground plant parts from infection by airborne pathogens or feeding by insect pests and disease vectors; improved vigor and uniformity of crop growth; deterrence of deterioration or insect feeding in storage; fulfillment of phytosanitary requirements and prevention of pathogen spread. These benefits all contribute to maximizing crop yield and quality while minimizing negative impacts through efficient use of crop protection chemicals. Seed treatment allows for highly targeted application of low, uniform doses of product, which is effective while reducing the risk of selection pressure for pathogen or pest resistance. Seed treatments are commercially available with contact, locally systemic, or fully systemic activity. Common active ingredients can be used for protection against Oomycetes, fungi, insects, and nematodes. There are numerous examples of improvements in stand establishment and yield as a result of seed treatment use in a wide range of crops. Combinations of active ingredients are becoming more common as products improve for efficacy against specific pathogen groups. In maize, seed treatment is nearly universal and standard practices may include a combination of four fungicides, an insecticide, and a nematicide. This provides a high level of protection across a wide pathogen spectrum as well as prevention of feeding damage to the seed and seedling. Seed treatments are playing an increasing role in the productivity of agriculture, as well as its sustainability and efficiency. Seed application of crop protection compounds provides unique benefits that make it a preferable approach compared to other tactics. It is a reliable technology that guarantees a uniform crop establishment in a variety of environments, soils and cultural practices; benefits provided by seed treatments cannot be duplicated because most of the target diseases and pests cannot be controlled after planting.

Quinazolin-4-ones, Thienopyrimidin-4-ones and Related Compounds: New Highly Active Powdery Mildewicides [1]

In this short review, new quinazolinones and thieno-pyrimidinones with outstanding powdery mildew activity are introduced. The most important inventions of two major players in this field, DuPont and Syngenta, are presented and interesting strategies for the synthesis of 2-alkoxy-3-alkylthieno[2,3-d]pyrimidin-4-ones and related compounds are discussed in detail. The biological activities of selected compounds including the highlights, 6-bromo-2-propoxy-3-propylquinazolin-4-one and 6-chloro-2-propoxy-3-propylthieno[2,3-d]-pyrimidin-4-one are compared and discussed.