Plant diseases are a major constraint to productivity in rainfed agricultural systems. This chapter examines the nature of diseases in cropping systems, thresholds for management, major management tools, integrated disease management and the challenges for translating knowledge into practice. Inputs for disease management should be based on well-defined thresholds, but these are poorly developed for most diseases and regions. Disease management in rainfed agriculture relies mostly on alterations to crop husbandry and the use of resistant varieties; fungicide use is generally restricted to tactical application in higher value crops. Many tools such as rotation, nutrition and management of crop residues interact strongly with other components of the farm system and their effective use requires complex decisions. Much of the information required to give sustainable control of most crop diseases in rainfed agriculture is already known. There is a continuing need to convert this knowledge into forms that can be used for on-farm decision making, especially in traditional and marginal areas.

'Acacia' s.s. comprises approximately 1020 species (i.e. just under one-third of all mimosoid legumes) and is almost entirely restricted to, although widespread, on the Australian continent. We investigated variation in the wood anatomy of 12 species from temperate New South Wales in a study concentrating on four recognised taxonomic sections ('Botrycephalae', 'Juliflorae', 'Phyllodineae' and 'Plurinerves'), to elucidate which characteristics are consistent within the sections, having removed climatic effect as much as possible. The sections had great utility in species identification, whereas none of the wood characters reflected the hypothesised phylogeny of the genus. The main consistent difference among species was in ray width (uniseriate versus 1-3 cells wide). All species had distinct growth rings. The vessels had alternate vestured pitting and simple perforation plates. Fibres were generally thick-walled, and many fibres had a gelatinous inner wall (tension wood fibres) and were inconsistently distributed. Axial parenchyma was mainly paratracheal, ranging from vasicentric to confluent and varied greatly in abundance. Prismatic crystals were usually present in chambered fibres and axial parenchyma strands, and also varied in abundance. The variation in these qualitative characters obscures taxonomic differences, but may allow inferences to be made about environmental adaptation.