4.9.6
AZOXYSTROBIN: A NOVEL, BROAD-SPECTRUM FUNGICIDE BASED ON THE NATURAL STROBILURINS

SC KNIGHT1, D COLLINGE1, RSI JOSEPH2, M MOSS1 and A SAPIETS2 1Zeneca Agrochemicals, Fernhurst, Haslemere, Surrey, GU27 3JE, UK; 2Zeneca Agrochemicals, Jealott’s Hill Research Station, Bracknell, Berkshire, RG42 6ET, UK

Background and objectives
Azoxystrobin is a new fungicide with a novel biochemical mode of action. Its synthesis was inspired by a group of natural products, the strobilurins, which are produced by several species of Basidiomycete fungi. Azoxystrobin shares its biochemical mode of action with these natural strobilurins. It demonstrates a very broad spectrum of activity and is active against fungal pathogens from all four taxonomic groups, the Oomycetes, Ascomycetes, Deuteromycetes and Basidiomycetes [1, 2].

The site of action of azoxystrobin is the fungal mitochondrion, where it binds to the cytochrome bc1 complex, thereby preventing electron transfer and energy production via oxidative phosphorylation. It is not cross-resistant to other site-specific fungicides such as the benzimidazoles, DMIs or phenylamides. Azoxystrobin therefore represents an effective new tool for the management of resistance, which is frequently a significant factor in the choice of fungicide products.

Azoxystrobin possesses a benign environmental profile and is unique in combining an excellent spectrum of activity with high levels of fungicidal potency at low application rates. As a result, it is registered as a reduced risk pesticide in the USA, and registrations for azoxystrobin are expected on more crops and in more territories worldwide than for any other fungicide that has been developed in recent years.

This poster describes the studies that have been carried out to determine the fate of azoxystrobin in the environment and to quantify residue levels found in the crop following applications of azoxystrobin. Field trial data are also presented to illustrate its efficacy against economically important fungal pathogens of a diverse number of crops.

Results and conclusions
Extensive studies confirm that azoxystrobin has a good toxicological profile. The molecule is rapidly degraded in the environment and does not accumulate in the food chain. It represents a low risk to non-target organisms, making it suitable for inclusion in integrated crop management (ICM) and integrated pest management (IPM) programmes. The use of azoxystrobin as directed results in low or non-detectable residues in the crop. Studies demonstrate that residues in processed foods are generally lower than in the harvested commodity. Field trials have demonstrated azoxystrobin's global fit through its effectiveness against diseases of many commercially important crops, including cereals, grapevine, rice, banana, peanut, cucurbits and tomato. These data also confirm that azoxystrobin delivers significant crop yield and quality benefits as a result of its broad-spectrum disease control.

References
1. Godwin JR, Anthony VM, Clough JM, Godfrey CRA, 1992. Proceedings Brighton Crop Protection Conference: Pests and Diseases. BCPC, Farnham, pp. 435-442.
2. Heaney SP, Knight SC, 1994. Proceedings Brighton Crop Protection Conference: Pests and Diseases. BCPC, Farnham, pp. 509-516.