Phytophthora parvispora

Phytophthora parvispora is a pathogenic oomycete known for causing significant diseases in various plant species. As a soil-borne pathogen, it primarily targets the root system, inducing severe root rot that impedes nutrient and water uptake, eventually leading to the rapid decline and death of the host plant.

The pathogen has a diverse host range, frequently affecting nursery stock, ornamental trees, and certain shrub varieties. Its ability to persist in the soil and infect roots makes it a major threat to agricultural and horticultural production, especially in environments where plants are grown in intensive conditions.

Symptoms are often manifested as foliar yellowing (chlorosis), wilting, and overall stunted growth. A diagnostic feature is the browning and decay of the roots, which often appear mushy or necrotic. The crown or root collar may also show dark, sunken lesions as the infection progresses upward from the subterranean parts of the plant.

The disease development is heavily dependent on moisture. Phytophthora parvispora thrives in waterlogged or overly saturated soil, which allows its mobile zoospores to swim through the water film to reach healthy roots. Contaminated irrigation water, infested soil, and non-sterilized pruning tools are the primary vehicles for its spread across nursery facilities.

Integrated pest management is crucial for the control of this pathogen. Key measures include maintaining excellent drainage to avoid water stagnation, using certified disease-free planting materials, and implementing strict hygiene protocols. Chemical control involves the application of fungicides, particularly those targeting oomycetes, as part of a preventive program.

• Implementation of proper soil drainage.
• Sterilization of pots and nursery equipment.
• Use of certified, pathogen-free substrates.
• Immediate removal of infected host material.