Critical review of Identification Techniques for Armillaria spp. and Heterobasidion annosum Root and Butt Rot Diseases

The need for a rapid and definite diagnosis of the Armillaria spp. and Heterohasidion annosum root and butt rot diseases as well as general requirements expected of a test to detect the pathogens are reviewed. As a spin-off from more fundamental molecular biological research there has been a remarkable increase in new methods for diagnosis (i.e. detection and identification) in recent years. These new methods all have in comtnon that they use strtjctural elements of the target organisms such as proteins, polysaccharides, glycoproteins, nucleic acids, etc. for the construction of antibodies, probes and primers for detection, or to produce electrophoretic patterns to be used for classification and identification. This paper presents a short review of principles, advantages, disadvantages and some perspectives of the new methods developed for Armillaria spp. and H. annosum diagnosis compared with conventional ones, such as interfertility testing or visual inspection of the pathogens in situ and in vitro in pure culture. It will be noted that the specificity and reproducibility of the new techniques, which are closely linked with potential experimental error, lead to principal pitfalls which should be kept in mind when conclusions are drawn on data generated by them. Even though PCR-based methods become increasingly more widespread it is likely that most diagnostic methods will continue to be used or co-exist in some form in the future