Azole fungicides

Multi-residue methods (S19) to measure azole fungicides in crop samples... 

The analysis of azole compounds is becoming increasingly important. For the regulation of their residues, the multi-method Deutsche Forschungsgemeinschaft (DFG) S19 is used throughout Europe. Within the last few years, this method has been validated for many new azole fungicides in various crop matrices. The multi-residue method and the most important procedural details for the detection and determination of azole compounds are described below. Some important properties are shown in Table 1. 

As an extension towards azolic fungicides, phenacylation was next examined. Under the action of microwave irradiation, exclusive reaction in position 1 (or equivalent 2) occurred whereas mixtures of N1 N4 and N14 products were obtained by A under the same conditions [115] (Eq. (65) and Tab. 3.26). 

The recent reviews by Jager (11) and Kramer et al (12) describe the synthetic routes and biological activity of selected tritylimidazoles, trityltriazoles and other variously substituted N-azole fungicides. The information that follows will describe certain structural activity relationships of selected EBI fungicides containing pyridine and pyrimidine heterocyclic moieties. 

A8,7 Isomerase and A14 Reductase. Before the appearance of resistance to azole fungicides in cereal powdery mildew the A8,7 isomerase and A14 reductase inhibitors were of minor importance because of their limited spectrum. Only seven examples of this group have shown commercial potential fenpropimorph, fenpropidin, tridemorph, dode-morph, aldimorph, piperalin, the first member of the series, introduced by Eli Lilley (now Dow Agrosciences) in 1960, and spiroxamine, the latest addition (Figure 4.5). 

Figure 15. Azole fungicides and antimycotics from other subgroups.

C-labelled active plant protection substances for 13 years (17, 18). The results indicate that intensive cooperation between plant protection chemists, phytopathologists, phytophysiologists and specialists in the radioisotope techniques is necessary to fully exploit the application possibilities and to interpret the results. The special experimental facilities at the JUlich Nuclear Research Center which include practically oriented field tests supplemented by detailed studies under defined climatic conditions enable practical and relevant results to be obtained (17-19). The aim of this contribution is to provide new insights and information on the system effectiveness and residue behavior of azole fungicides. 

Over the last few years, a number of papers have described the influence of the azole fungicides on fungal growth and the important points of attack in the host-pathogen-system. In this paper several of these results will be presented. 

Most of the work on the mode of action of the azole fungicides has been conducted with Ustilago species. In early experiments by Buchenauer (2), it was evident that triadimefon caused the sporidia of Ustilago avenae to lose their capacity for normal cell division. In nutrient solutions containing the fungicides, the sporidia, which normally separate after division, remained bound in mycelial-like clusters. 

Investigations with several host-pathogen-systems have shown that the azole fungicides can have three effects ... 

It is of special interest that the type of encapsulation seen in barley varieties with high resistance against powdery mildew is the same as that seen in the azole fungicide treated plants. This suggests that the fungicide induces some kind of resistance reaction in the host plant. 

Spore germination of Venturia inaequalls, the apple scab fungus, is also unaffected by the studied azole fungicides. They prevent... 

In my following presentation, I would like to illustrate a special chapter of these contributions—"The History of Azole Fungicides". In the background of this story you may find some indication of the ingredients for successful research a brigit idea, freedom of activity, flexibility, patience, persistence, and last, but not least, good fortune. 

This volume contains the presentations given by eminent members of the scientific community to honor Karl Buchel. Experts from the United States and Europe were brought together to discuss aspects of the chemistry of azole fungicides and ways in which this chemistry is being used for disease control in major food crops. 

Since their discovery in the late 1960s several compounds from the chemical class of 1-substituted imidazoles and 1,2,4-triazoles have been developed and successfully used for the control of plant diseases and for the treatment of human fungal infections. The first commercial triazole compound was triadimefon ( 1J, introduced by Bayer in 1973 for the control of powdery mildew, rusts, and seed-borne diseases of cereals. Since that time many other so called "azole-fungicides" have been introduced into crop protection (2) and others are still being developed. 

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