Phytophthora cactorum

A plant pathogen affecting a wide range of hosts

Phytophthora cactorum is a plant pathogen that affects a wide range of host plants, causing diseases such as crown rot, root rot, and fruit rot. It is a member of the Oomycetes, a group of fungus-like organisms that are more closely related to algae than to true fungi.

Description

Phytophthora cactorum is characterized by its production of sporangia, which are asexual spores that can spread through water and infect plants. The sporangia are typically lemon-shaped and can release zoospores, which are motile spores that swim through water to find new hosts.

Life Cycle

The life cycle of Phytophthora cactorum involves both asexual and sexual reproduction. In the asexual phase, sporangia release zoospores that swim to plant surfaces, encyst, and germinate to infect the host. In the sexual phase, the pathogen produces oospores, which are thick-walled spores that can survive in soil for extended periods.

Hosts

Phytophthora cactorum has a broad host range, including strawberries, apples, pears, and rhododendrons. It is particularly notorious for causing crown rot in strawberries and collar rot in apple trees.

Symptoms

Infected plants may exhibit symptoms such as wilting, leaf discoloration, and dieback. In strawberries, crown rot can lead to plant collapse and significant yield loss. In apple trees, collar rot can girdle the trunk, leading to tree death.

Management

Management of Phytophthora cactorum involves cultural practices, chemical treatments, and resistant plant varieties. Cultural practices include improving soil drainage and avoiding over-irrigation. Chemical treatments may involve the use of fungicides, although resistance can develop. Breeding for resistant varieties is an ongoing area of research.

Related pages

• Phytophthora
• Oomycetes
• Plant pathology
• Crown rot
• Root rot