Articles
Red star rust (Gymnosporangium yamadae) on Malus spp. in United States public gardens
Article number
1434_28
Pages
205 – 204
Language
English
Abstract
Flowering crabapple trees (Malus spp.) are prized for their colorful spring blooms and brilliant autumn fruit.
They are a valuable deciduous ornamental commodity and are represented in public gardens worldwide.
In 2009, red star rust (also known as Japanese apple rust) caused by Gymnosporangium yamadae (Miyabe ex Yamada 1904), was first detected in the United States (US). The disease has since been reported in a dozen Midwest and northeastern states.
The aecial stage was confirmed in Minnesota in 2022. Characteristic symptoms on flowering crabapple include circular to irregular lesions in hues of red, orange, and/or yellow with a vibrant red margin.
The objective of this investigation was to assess red star rust disease incidence of flowering crabapple specimens at the Minnesota Landscape Arboretum (Chaska, MN). The collection comprises 165 associated taxa within its 485-ha property and provides an opportunity to evaluate regionally hardy taxa.
We visually observed and recorded macroscopic foliar signs and symptoms in September and October 2023. Disease incidence was measured as the number of specimens per taxon that displayed symptoms.
Sixteen symptomatic leaf samples were gathered for molecular identification by amplifying and sequencing 28S rDNA using primers NL1/4. Seventy-three of 519 specimens exhibited symptomatic red star rust lesions with greater disease incidence observed on six taxa.
Six samples representing unique Malus taxa resulted in a positive identification for G. yamadae in preliminary sequencing analyses with four additional positives identified during subsequent sequencing runs.
Data collected indicate that many flowering crabapple taxa are susceptible to infection by G. yamadae. These results also suggest that disease is widespread within the flowering crabapple plantings at the Minnesota Landscape Arboretum and that public gardens may serve as a resource for early detection of emerging pathogens.
They are a valuable deciduous ornamental commodity and are represented in public gardens worldwide.
In 2009, red star rust (also known as Japanese apple rust) caused by Gymnosporangium yamadae (Miyabe ex Yamada 1904), was first detected in the United States (US). The disease has since been reported in a dozen Midwest and northeastern states.
The aecial stage was confirmed in Minnesota in 2022. Characteristic symptoms on flowering crabapple include circular to irregular lesions in hues of red, orange, and/or yellow with a vibrant red margin.
The objective of this investigation was to assess red star rust disease incidence of flowering crabapple specimens at the Minnesota Landscape Arboretum (Chaska, MN). The collection comprises 165 associated taxa within its 485-ha property and provides an opportunity to evaluate regionally hardy taxa.
We visually observed and recorded macroscopic foliar signs and symptoms in September and October 2023. Disease incidence was measured as the number of specimens per taxon that displayed symptoms.
Sixteen symptomatic leaf samples were gathered for molecular identification by amplifying and sequencing 28S rDNA using primers NL1/4. Seventy-three of 519 specimens exhibited symptomatic red star rust lesions with greater disease incidence observed on six taxa.
Six samples representing unique Malus taxa resulted in a positive identification for G. yamadae in preliminary sequencing analyses with four additional positives identified during subsequent sequencing runs.
Data collected indicate that many flowering crabapple taxa are susceptible to infection by G. yamadae. These results also suggest that disease is widespread within the flowering crabapple plantings at the Minnesota Landscape Arboretum and that public gardens may serve as a resource for early detection of emerging pathogens.
Authors
T.B. Enzenbacher, M.D. Clark, B.W. Held, R.A. Blanchette, M.A. Grabowski, B.M. Miller
Keywords
rust, apple, crabapple, botanical gardens, arboreta
Online Articles (52)