galls on juniper

Asked April 29, 2013, 5:16 PM EDT

i'have been working for 10 yrs. on 2, 15 yr old nursery stock junipers. they are developing into quite handsome bonsai. last week I noticed a number of 3/8dia. brown round galls on the needled branches. i broke one of the galls open and under the surface brown outer cover was green woodlike interior. today it rained and the galls had overnight become engulfed in a light brown spongy mushroom like fungus. What have I got and how do I treat it ? my best guess is a fungicide . which one and what dosage. I work on these trees every day wiring branches and needle pruning and i would hate to lose them. thanks jeff walder
PS: the galls are morphing into light brown colored, gelatinous textured,wavy south seas giant clam shell shaped blobs .Some are starting to creep up the branches.(sounds like a horror show; huh?) Over our house is a huge hackberry tree whose leaves are gall deformed (the host?). Some of the galled juniper branches have died while others appear healthy. Can I just scrape off the gall and gelatinous stuff or prune the branch below the gall. the gall is round shaped and encircles each branch. .No horns have yet appeared on the gall (but the devil lurks and the night is young ).
Thanks Dr. M

Cumberland County Pennsylvania trees and shrubs master gardener program bonsai culture

1 Response

It sounds like Juniper-Hawthorn Rust, also known as cedar-apple rust. The fungus that causes this disease will produce orange jelly-like balls on juniper branches. This orange gelatinous material, which contains thousands of spores, oozes out of chocolate-colored galls present on affected branches. Spores then are carried by the wind to the pathogen's alternate host. That's where the hawthorn or apple comes in. The causal fungus must have two hosts to complete its life cycle. Symptoms on the alternate host are very different than on junipers. Greenish yellow spots will appear in June on the leaves of hawthorn, mountain ash, apples, crabapples or other alternate hosts. Spores produced on these leaves then blow back to the juniper or cedar and the cycle starts all over again. The disease cycle is two years: 18-20 months on juniper and 4-6 months on the alternate host. To control this disease:
1) Separate the hosts. The rust fungus cannot survive in the absence of one of the hosts. 2) Remove rust galls. Juniper galls and the resulting orange gelatinous extrusions should be pruned out in late winter or early spring. 3) Fungicide sprays also are available but seldom are necessary.