Goo-ey globule

What is that thing?!

It was about 1 1/2 inches in diameter, orange and gelatinous:  yuck!  I was doing some planting and when I turned around to see what was brushing against my head I saw this.

This amazing sphere is actually a fungus called Gymnosporangium juniperi-virginianae, and it is what causes Cedar-apple rust.  This so-called ‘rust’ causes the orange spots you see on apple leaves, causing leaf drop that can prematurely defoliate trees and potentially weaken them (not to mention de-face the apples themselves).

This fungus (one of several rust diseases in the genus Gynosporangium) needs both a Rosaceous and Juniper (known as ‘red cedar’) host to complete its life cycle.   The gelatinous fungus that is pictured here has emerged from a dry, woody gall that protected it through the winter months.  When the spring warmth and moisture begins, the fungus is activated and takes on its crazy appearance.

 ASIDE:  You will have probably seen this spherical growth on goldenrod plants.  It is not caused by a fungus but rather by the goldenrod gall fly, whose life cycle is entirely dependent on this native plant and is described here.

 Once you see this squishy orange stage of the fungus on juniper plants, the sphere is about to morph to include horn-like growths.  These will release spores that travel on the wind to their companion apple host (which could be miles away), where the cycle will continue.

The accepted control for the home garden is keeping an eye out for this brightly coloured fungus, choosing not to grow apples and junipers near eachother and growing rust-resistant varieties of both plants.


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