The aim of this article is to show the importance of fungal taxonomy for phytopathology. In the first section, the relationships between the teleomorphs (perfect state) and the anamorphs (imperfect state) of phytopathogenic Fungi are explained. Examples such as Pseudocercosporella spp. (teleomorph unknown until recently), Fusarium graminearum (teleomorph is very important for the disease cycle) and Monographella nivalis (frequent name changes of both teleomorphs and anamorphs) are described. From the examples mentioned, the necessity for an intensive revision of fungal systematics for plant pathology becomes obvious. Section 2 illustrates the importance of the accurate identification of species and sub-specific groupings, using Pseudocercosporella species and Rhizoctonia solani as examples. Uncertain boundaries between species, which exist even today in these genera, lead to uncertainties among phytopathologists as to the host range, disease cycles and most importantly, control methods for these pathogenes. Intensive research with members of these two genera has led to some progress in the clarification of their taxonomy, but there is still room for improvement. In section 3, the relevance of taxonomic studies fur mycotoxin research is treated. The prominent role Fusaria play as mycotoxin-producers, has made them focus of several investigations. The results of analyses done with different isolates are difficult to compare, because of the non-uniform nomenclature for the test organisms. A solution to this problem through a clarification of the taxonomic relationships is urgently needed. Section 4 describes fungal metabolites and properties, which are of significance in plant protection. Competent mycologists with a sound knowledge of fungal taxonomy are necessary to identity, describe and preserve important fungal strains. It is important that the candidate fungi be stored under conditions where they are stable and not to select for generically and physiologically altered strains during presentation. The conservation of fungal generic resources in well kept culture collections is obviously of great importance. Many have not been rested at all in respect to their usefulness for controlling plant diseases. Section 5 presents examples where taxonomic difficulties arise in quarantine measures. Thus, officers in plant sanitation departments are usually nor experts in fungal taxonomy and need the help of competent taxonomists, specially in the case diseases listed for quarantine changed the name or in some other critical situations.
