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).
Colors on either end of the spectrum play the greatest role in plant growth and flowering, while the yellow and green wavelengths play a lesser role. Plants use wavelengths between 400 and 700 nanometers (nm) for photosynthesis, which provides for all the energy needs of the plant.