Cedar Apple Rust (Gymnosporangium juniperi-virginianae Schwein.)
A bunch of miniature carrots?? Not at all. This is actually a cedar-apple rust gall, with orange jelly-like horns emerging from it.
Cedar-apple rust is caused by a plant pathogen called Gymnosporangium juniperi-virginianae. In places where apples or crabapples (Malus) and Eastern red-cedar (Juniperus virginiana) coexist, cedar apple rust can be a destructive or disfiguring disease on both the apples and cedars.
On the eastern red-cedar host, the fungus produces reddish-brown galls from 1⁄4–1 in (6.4–25.4 mm) in diameter. Many small circular depressions become apparent after the galls attain a diameter of about 1⁄2 inch (13 mm). In springtime, these structures elongate into orange gelatinous protrusions or horns known as telial horns which emerge during rainy periods in April and May. These telial horns bear teliospores and the wind carries these microscopic spores to infect apple leaves, fruit and young twigs on other trees located within a radius of several miles of the infected tree.
This spring’s frequent rains may be messing up my planned outdoor work schedule, but they have been a boon to many forms of life. Apple Cedar Rust Fungus depends upon high moisture conditions to properly complete the reproductive portion of its life cycle. The fungus has a two host life cycle, shuttling back and forth between apple trees and cedars. Each spring, the cedar bound fungus sheds spores that will make their way to apple trees. In its spore producing form, the fungus resembles some weird sea creature that has washed up onto a tree branch.
Cedar-apple rust is caused by a plant pathogen called Gymnosporangium juniperi-virginianae. In places where apples or crabapples (Malus) and Eastern red-cedar (Juniperus virginiana) coexist, cedar apple rust can be a destructive or disfiguring disease on both the apples and cedars.
On the eastern red-cedar host, the fungus produces reddish-brown galls from 1⁄4–1 in (6.4–25.4 mm) in diameter. Many small circular depressions become apparent after the galls attain a diameter of about 1⁄2 inch (13 mm). In springtime, these structures elongate into orange gelatinous protrusions or horns known as telial horns which emerge during rainy periods in April and May. These telial horns bear teliospores and the wind carries these microscopic spores to infect apple leaves, fruit and young twigs on other trees located within a radius of several miles of the infected tree.
This spring’s frequent rains may be messing up my planned outdoor work schedule, but they have been a boon to many forms of life. Apple Cedar Rust Fungus depends upon high moisture conditions to properly complete the reproductive portion of its life cycle. The fungus has a two host life cycle, shuttling back and forth between apple trees and cedars. Each spring, the cedar bound fungus sheds spores that will make their way to apple trees. In its spore producing form, the fungus resembles some weird sea creature that has washed up onto a tree branch.
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23 January 2023
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