80 CONTENTS 13.1 Introduction 13.2 Eucalyptus diseases (gum) 13.3 Acacia diseases (wattle) 13.4 Pinus diseases (pine) 13.1 Introduction This chapter deals only with the major diseases of commercial forestry trees in South Africa.0 CONTENTS 13.1 Introduction 13.2 Eucalyptus diseases (gum) 13.3 Acacia diseases (wattle) 13.4 Pinus diseases (pine) 13.1 Introduction This chapter deals only with the major diseases of commercial forestry trees in South Africa.
The pigment responsible for most light-harvesting by plants is chlorophyll, a green pigment. The green color indicates that it is absorbing all the non-green light-- the blues (~425-450 nm), the reds and yellows (600-700 nm).
Most land plants are green (their stems and leaves, anyway) because the accessory pigments are chlorophylls, including chlorophyll-b and chlorophyll-c. When green leaves turn colors in the fall, or turn yellow due to nutrient limitation or disease, the chlorophylls are breaking down and being re-absorbed, allowing the other pigments to show through.