Gymnosporangium juniperi-virginianae.
Cedar apple rust is a fungus that attacks crabapples, apples and the eastern red cedar which is in fact a Juniper and some other Junipers. Hence the name....Cedar apple rust.
This fungus survives by moving from one of these species to the other; Juniper to apple....Apple to Juniper...back and forth.
The photo above is that part of the process found on the Red Cedar or other Junipers. It starts out as a small 3/8 to 1 1/4" gall found on small branches and needles....like this
and then after 4-6 hours of wet spring weather at temps of 50-75 degrees, the galls swell and start to produce the gelatin like horns that make them so scary looking. These galls eventually die when the wet spring weather subsides but the twig above the gall will probably die.
So, if you see these galls it is best to prune them out as soon as possible to help prevent the spread of this fungus to your apples and crabapples.
Now you know half the story. Here is the other half.
The apples and crabapples.
As those scary looking orange galls swell they start and continue to release spores into the air. These spores can travel several miles to the poor, unsuspecting apple or crabapple trees but normally they spread only a few hundred feet. During this same cool wet period tiny little yellow spots will appear on the leaves of the apples and crabapples.
As these spots age they also swell a bit and take on a red border with a tiny black spot in the center.
By the middle of summer these spots will have developed a small and clearly visible tube shape protrusion on the under side of the leaves. From these tube like structures under the leaves spores again are released and head to the nearest Juniper or Red Cedar for a nice warm place to spend the fall and winter. The next spring these galls will appear and start to grow until the following spring when they will start to swell with the wet spring weather and again turn into that scary orange thingy. At this point they release those nasty spores to start the entire 24 month process all over again.
The best solution to all of this is to first remove all galls from the Juniper or Red cedar or if it is heavily infected remove the entire plant or tree. Next plant only resistant varieties of apples and crabapples.
If you find the galls and your apple or crabapple have not yet been infected or in the case of trying to slow down this 2 year procession you may want to spray with Daconil or Clearys 3336 fungicide.
Now that you know "what" it is.... you no longer need to run in fear.
You know, I think I am finally typed out!!!!
