Abstract
Development of pink disease on the various ages of Acacia crassicarpa Cunn Ex. Benth.. The increase in the value of pulp and paper exports in Indonesia is partly due to the development of industrial forest plantations of acacia on peatlands. Acacia crassicarpa grows well on peatlands with high productivity. However, the development of pink disease is a threat to the growth of A. crassicarpa, both in the nursery and in the field. This study aimed at examining the development of pink disease on the various ages of A. crassicarpa. The study was conducted using census method on plants at aged 4, 24 and 42 months. Variables observed were symptoms, incidence, and severity of disease. Data were analyzed descriptively and regressively to understand the relationship between the incidence and severity of the disease and the age of the plant. The results showed that the symptoms that appearing at the seedling level were similar to those the sapling, poles and tree level. The presence of thin colonies of cobweb-like (cobweb stage), mycelia aggregation from the cobweb stage (pseudonodular stage), and the appearance of pustules and pink incrustation (teleomorph stage) were common symptom. However, disease incidence and severity were moderate at the seedling and mild at the saplings, poles and trees level. The incidence and severity of disease decreased with increasing age.