Preface

Considerable advances in the understanding of herbicides in soils and/or in plants have been made over the past decade. Elucidation of the synthetic pathways of herbicides is continuing apace and, while their function is still open to controversy, it is now widely acknowledged that these compounds are not, in general, biomaterials but are artificially synthesized.

Exciting discoveries are continually being made in the field of herbicides. Since the completion of this book, it has been reported that the mode of action of herbicides is still in need of further investigation in order to cope with weed control.

The overall purpose of this book is to show that plants do not haphazardly produce a large number of chemical compounds, but that each compound is synthesized for a definite purpose and that the majority of herbicides and pesticides are artificially synthesized in the labs; investigating synthetic pathways and properties, and that all products produced to overcome weeds and insects which causes low production of crops.

The format of the book is based on two main sections: Synthesis and Properties of Herbicides and Control of Weeds. This book contains 25 review articles on a wide range of important topics. Several chapters review herbicide progress in specific crops. Other chapters deal with the synthesis and properties of herbicides and weed control. I hope therefore that readers who are interested in a synthesis and properties and control of weeds, for example in winter wheat of early growth stages, effects of herbicides on fresh water zooplankton, and herbicide tolerant food legume crops, will benefit from the wider range of topics also discussed within this book.

> **Prof. Dr Mohammed Naguib Abd El-Ghany Hasaneen** Professor of Plant Physiology, Plant Department, Faculty of Science, Mansoura University, Egypt

**Part 1** 

**Synthesis and Properties** 

**Part 1** 

**Synthesis and Properties** 

**1** 

*Brazil* 

**Preparation and Characterization of Polymeric** 

There is increasing pressure to improve agricultural productivity, due to rapid population growth, increased consumption and global demand for high quality products. As a result, agricultural chemicals have become essential for the control of weeds, pests and diseases in a wide range of crops. Ametryn (2-ethylamino-4-isopropylamino-6-methylthio-s-2,4,6 triazine) is a selective herbicide belonging to the s-triazine family, whose activity is the result of inhibition of photosynthesis by blocking of electron transport. The ametryn molecule (Figure 1) contains a symmetrical hexameric aromatic ring in its chemical structure, consisting of three carbon atoms and three nitrogen atoms in alternate positions. The herbicide is classified as a methylthiotriazine, due to the presence of the SCH3 group

Ametryn is used for the control of graminaceous and broad-leaved weeds in plantations of annual crops (Tennant et al., 2001). Once in the soil the herbicide may be taken up by plants, absorbed by the soil and plant residues, biodegraded, or undergo chemical transformations that increase its volatilization and photocatalytic decomposition. Studies have shown that prolonged human exposure to triazine herbicides can lead to serious health problems including contact dermatitis, intoxication, hormonal dysfunction and cancers (Friedmann et

**1. Introduction** 

(Tennant et al., 2001).

Fig. 1. Structural formula of ametryn.

**Microparticles Used for Controlled Release** 

Fabiana A. Lobo1, Carina L. de Aguirre2, Patrícia M.S. Souza2,

*3Department of Environmental Engineering, Campus Sorocaba, SP,* 

**of Ametryn Herbicide** 

Renato Grillo2,3, Nathalie F.S. de Melo2,3, André H. Rosa2 and Leonardo F. Fraceto2 *1UFOP - Universidade Federal de Ouro Preto 2UNESP – State University of São Paulo,* 
