Gymnosporangium yamadae

Gymnosporangium yamadae is a species of fungus in the family Pucciniaceae. It is a rust fungus, a type of plant pathogen, known for causing the disease apple rust in apple trees.

Taxonomy

The species was first described scientifically by the Japanese mycologist Yosaburo Yamada in 1905. The genus name Gymnosporangium comes from the Greek words gymnos (naked) and sporangium (spore vessel), referring to the exposed spore-producing structures of these fungi. The species name yamadae is in honor of its discoverer.

Description

Gymnosporangium yamadae is characterized by its complex life cycle, which involves two different host plants: members of the Rosaceae family, particularly apple trees (Malus domestica), and junipers (Juniperus spp.). The fungus produces orange, gelatinous telia on the leaves, twigs, and fruit of infected apple trees in the spring. These telia produce teliospores, which are wind-dispersed and infect junipers. On the juniper host, the fungus produces aecia, which release aeciospores that infect apple trees, completing the life cycle.

Distribution and habitat

Gymnosporangium yamadae is native to East Asia, including Japan, Korea, and China. It has been introduced to other parts of the world, including North America and Europe, where it is considered an invasive species. The fungus is found in areas where its apple and juniper hosts coexist.

Impact and control

Gymnosporangium yamadae is a significant pathogen of apple trees, causing a disease known as apple rust. Infected trees exhibit yellowish-orange lesions on the leaves, twigs, and fruit, which can lead to defoliation and reduced fruit yield. Control measures include the use of fungicides, removal of infected plant material, and planting of resistant apple varieties.

See also

• List of apple diseases
• List of Pucciniaceae species