Chrysomyxa weirii

Chrysomyxa weirii symptoms1

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Chrysomyxa weirii is a species of fungus in the family Coleosporiaceae. It is a plant pathogen known to cause spruce needle rust in various species of spruce trees. This pathogen is particularly significant in forestry and horticulture due to its impact on tree health and commercial value.

Description

Chrysomyxa weirii is characterized by its production of yellow to orange urediniospores on the needles of infected spruce trees. These spores are responsible for the spread of the disease during the growing season. The fungus also produces teliospores that overwinter on fallen needles, which germinate in the spring to produce basidiospores that infect new needles.

Life Cycle

The life cycle of Chrysomyxa weirii involves both asexual and sexual reproduction. The asexual stage occurs on the needles of spruce trees, where urediniospores are produced and dispersed by wind. The sexual stage involves the production of teliospores, which undergo karyogamy and meiosis to produce basidiospores. These basidiospores then infect new host needles, completing the cycle.

Hosts

Chrysomyxa weirii primarily infects species of spruce, including:

• Picea sitchensis (Sitka spruce)
• Picea glauca (white spruce)
• Picea engelmannii (Engelmann spruce)

Symptoms

Infected spruce trees exhibit several symptoms, including:

• Yellow to orange discoloration of needles
• Premature needle drop
• Reduced growth and vigor
• In severe cases, tree mortality

Management

Management of Chrysomyxa weirii involves several strategies:

• Cultural control: Removing and destroying infected needles and debris to reduce the source of inoculum.
• Chemical control: Application of fungicides to protect new growth from infection.
• Resistant varieties: Planting resistant or less susceptible species of spruce.

Impact

The impact of Chrysomyxa weirii on forestry and horticulture can be significant, leading to economic losses due to reduced timber quality and increased management costs. The aesthetic value of ornamental spruce trees can also be affected, making them less desirable for landscaping purposes.

See also

• Plant pathology
• Fungal diseases of plants
• Forestry