Search

This chapter summarises research carried out on the biology, ecology and the impact of the holomorph Apiognomonia quercina/Discula quercina in oak forests. The major life-history traits and aspects of the epidemiology (isolation, survival, reproduction, dispersal, host selectivity) and control of the oak anthracnose agent are elucidated. The role of weather patterns in disrupting the delicate interaction between the host tree and the microorganism is outlined. The evidence suggests that changes in the climate profoundly alter the plant-endophyte symbiosis, generating conflicts of interest between the partners in the interaction. When such competing interests arise, the survival and reproduction of one member of the interaction do not conform with that of the partner. The interaction becomes thus disadvantageous and harmful to one of the organisms and the symbiosis from mutualistic or neutral turns antagonistic. The fungal partner, which under normal conditions survives in quiescence, with a low biomass, resumes growth but now switches from a latent, asymptomatic occupier of inner oak tissues to an aggressive coloniser that sporulates profusely over the tree surface. The importance of investigating the functioning and the role of the plant-endophyte symbiosis in perennial host trees in natural forests is stressed.

This chapter reviews strategies in rust control, with a special emphasis on biological control, in the light of evidence produced in recent years showing that plant disease control is most effective when an integrated management approach is followed. A survey of the fungal antagonists (hyperparasites) most effective against rust pathogens is given. The mode of action of these antagonists is described, and the main problems concerning biological control are discussed, on the basis of the optimal characteristics of an antagonist or biocontrol agent. The value and limitations of other control measures besides biological control (eradication, definition of hazard areas, quarantine, cultural practices, chemical treatments, and plant breeding for disease resistance) are also outlined. A consideration of all control measures suggests that crop protection requires a holistic approach integrating a broad range of control techniques.

Advanced molecular genetic techniques enhance our capabilities to identify and characterize microbial pathogens, resulting in accurate testing for pathogen identification, sub-species-level DNA fingerprinting, pathogen-load testing and disease spread monitoring. These applications are instrumental to the study of plant disease epidemiology, so that adequate control measures can be accordingly implemented. In this chapter, a survey of the most popular DNA profiling techniques is presented together with some of the newer and most discriminating molecular methods. Combinations of different analytical techniques are also proposed as a useful approach for low throughput bioassays. Advantages and disadvantages of each single test are taken into account and key issues (sampling, validation, large-scale testing, etc.), encountered in the practical application of these assays, are discussed. An outline of emerging high-throughput molecular technologies expected to improve diagnostic approaches and aid disease management is also provided.