Phytophthora inundata

Phytophthora inundata is a pathogenic oomycete known for causing severe root rot and crown rot diseases in various plant species. As a soil-borne pathogen, it thrives in waterlogged conditions, making it particularly problematic in nurseries, landscapes, and agricultural fields prone to flooding or poor drainage.

The host range of this pathogen includes a variety of woody plants, such as Alnus (alder) and Salix (willow) species, as well as several ornamental and fruit-bearing plants. It primarily targets the root system, causing decay that hinders the plant's ability to absorb water and essential nutrients from the soil.

Symptoms typically manifest as stunted growth, yellowing (chlorosis) of foliage, and premature wilting. In advanced stages of infection, the root system shows signs of necrosis and browning, while the crown area may develop dark, sunken lesions. If left unchecked, the disease leads to a rapid decline and eventual death of the affected plant.

The development and spread of Phytophthora inundata are heavily dependent on free moisture. The pathogen produces motile zoospores that can swim through saturated soil or irrigation water to reach healthy roots. Consequently, heavy rainfall, flooding, and contaminated water sources are the primary drivers of localized epidemics.

Management and prevention focus on eliminating environmental factors conducive to the pathogen. Essential steps include improving soil drainage, practicing strict sanitation of tools and containers, and using disease-free seedlings. When necessary, chemical control involves the application of fungicides, such as metalaxyl or fosetyl-aluminum, to prevent the spread and protect susceptible plants.