Serviceberry Galls

Gymnosporangium clavipes is a widespread rust (fungus) that infects over 480 species in 11 genera. Also called cedar quince/hawthorn rust, G. clavipes is heteroecious, meaning that it requires two alternate hosts to complete it life cycle.

One host, various members of Juniperus, is infected in late summer or early fall. The spores germinate, infect the host and then remain asymptomatic until the following spring. Infections result in mild swelling of twigs. The bark becomes flaky and many twigs die the first year of infection. Those twigs that survive become perennially infected and can produce spores for up to 20 years. The infection first appears as orange masses in bark cracks. After spring rainfalls, the infection gelatinizes into gooey masses (telia). The telia mature and release basidiospores which are carried by the wind. Any basidiospores that land on members of the rose family (second host), to which serviceberry (Amelanchier alnifolia) belongs, can germinate. Cedar quince/hawthorn rust may infect leaves, petioles, thorns, young branches or fruit of this second host. When the fruit is infected, long tubes (aecia) up to 1/2 inch form on the fruit. The fruit dies. In late summer or fall, the aecia release aeciospores, which are borne by the wind back to the primary host (Juniperus species) to begin the cycle again.

Generally, G. clavipes infection itself is not considered life-threatening to the hosts. However, infection can weaken the host and predispose it to injury from insects, weather or other pathogens.

Gymnosporangium clavipes galls on black hawthorn (Crataegus douglasii) are pictured in my post “Cedar Quince/Hawthorn Rust” from 08-03-16.

These serviceberry galls were on infected shrubs near the Lower Ash Creek Campground bridge (Lassen County CA).

This entry was posted in Fungi, galls, Rusts, Shrubs and tagged , , , , , . Bookmark the permalink.

2 Responses to Serviceberry Galls

  1. Edith Summers says:

    This post brings to mind the summer I spent in Newfoundland over 30 years ago now. I was already acquainted with juneberries or serviceberries from Northern Minnesota and Michigan. In those areas, they were one of the few edible fruits that ripened in the short northern summers, and could be gathered to cook with.
    So when we spent several months in eastern Newfoundland, I was happy to see the vast amount of Amelanchier growing so many places as I hiked around and explored the area. It grew lower than I had seen it before, so low that it was often like a ground cover, but it grew thickly and you couldn’t walk many places without treading on it. And when it bloomed in the spring (which was late June-early July there), the hills were covered with blossoms.
    What puzzled me was that when I asked local people about gathering the berries and cooking with them, they didn’t know anything about that. I tried all the common names I could find. The only common name that some of them recognized was saskatoon, but they told me that, although they had seen saskatoons in western Canada, they didn’t grow in Newfoundland. And here I was, unable to take a hike without treading on them. The people told me all about cooking with wild crowberries, blueberries, and bakeapples, but didn’t seem to know anything about these berries. So I was puzzled at what was going on.
    I did eventually find out that the local name was chuckley-pear, which is easy enough to find on the internet now, but took a lot of asking around for me to find it back then. But they told me chuckley-pears were inedible.
    Those were the days before there was internet, and the only key we had was Gray’s Manual, which didn’t actually have all the plants of Newfoundland. But I knew I was looking at Amelanchier, blooming in profusion, and I looked forward to all the berries, in spite of what the local people said.
    Later that summer, when the berries actually formed and ripened, I was so disappointed to find out that absolutely all of them were covered with cedar-apple rust, and were completely inedible. No wonder the people didn’t know about cooking with these berries! But the rust certainly didn’t prevent them from growing abundantly.

    • gingkochris says:

      Fascinating experience! Thanks for sharing. Plus I now have another common name to add to my “serviceberry” list. Colloquial names can cause confusion!

      Indeed, serviceberries are edible. Native Americans used them extensively in pemmican. Some of the serviceberries on our property are infected with rust and others are not. I wonder how long it will be until all are infected. I often will nibble on serviceberries while hiking, but have never collected large quantities.

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