Principles and Present Status of Chemical Control of Seedling Diseases

Abstract

The principal disease that occurs in forest nurseries is damping-off. This is difficult to control because of the following factors peculiar to nursery practice: 1) Natural microbiological balance in soil has been disturbed by such factors as cultivation, shading, fertilizing, watering, etc.2) The pathogens live in soil, in a well protected environment.3) Seedlings of one species are grown close together in dense stands, which facilitates the spread of diseases.4) The initial development of many tree species is slow, and the susceptible stage lasts a long time.