NY99029 - Improved Disease Management in the NSW Nursery Industry

The root rot fungus Phytophthora was isolated from 22% of used potting media and 20% of drainage water samples in this 1999-2002 study. The fungus was not found in fresh media samples or irrigation water, suggesting other likely entry points such as plants and seedlings brought onto nurseries and contaminated drainage water. In contrast, the fungal pathogen Pythium was isolated from 19% of fresh media and 13% of irrigation water samples. Management guidelines for diseases in irrigation water were reviewed and published in Managing Water in Plant Nurseries (Rolfe, Yiasoumi & Keskula, 2000). More than 500 ornamentals were diagnosed for plant diseases, providing new information for an updated checklist of diseases in NSW plants. Molecular techniques were developed for distinguishing Phytophthora species. Evaluation of commercial microbial biological controls to suppress plant diseases gave variable results.