Hi Brenda, I found an answer in a previous year about the rust.  Here it is:

Hello,

Rhamnus spp is an alternate host of oat crown rust. Here is an excerpt of an article about it, with details

“Oats are susceptible to a variety of plant diseases including fungal, viral and bacterial pathogens. The most common disease with economic significance is crown rust, also known as leaf rust. This disease is caused by Puccinia coronata avenae.

Spores are air-borne and can originate in southern states, or come from nearby buckthorn, an alternate host that allows the disease to overwinter. Wheat, barley and rye are not susceptible. Symptoms include small, oval, orange pustules on leaves. Pustules may also appear on leaf sheaths, stems and panicles.

The disease spreads from leaf to leaf as pustules release spores. Under conditions ideal for the disease, new pustules can form in 7 to 10 days. Damage to the oat plant is due to leaf damage.

A properly timed fungicide application can provide protection against crown rust. Spraying should take place at flag leaf emergence. If pustules have already formed on the flag leaf, it is too late. Fungicides labeled for crown rust in oats are protective, that is, they can prevent the disease from entering the plant. However, once the pathogen is inside, a protective fungicide won’t help.”

I could find no control options for ornamentals, all the interest is in oat crops. You could try a fungicide labeled for ornamentals and for rust, but I would prune out the affected leaves and destroy them. Keep the foliage of the shrub as dry as possible, re-directing sprinklers away from these plants. Water in morning so leaves dry quickly. Keep the shrubs watered during droughts since a stressed plant is more susceptible to all diseases. As the cool humid weather conditions for rust subside, and the new leaves harden off for the summer, you should see less of this disease.

References-

http://woodyplants.cals.cornell.edu/plant/print/212

https://www.ncbi.nlm.nih.gov/pubmed/28846186

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OK, that is a lot to read.  To sum up, the rust is from spores in the air and they land on the new tissue of the leaves.  With the right humidity and temperature, they will germinate and invade the cells of the leaf and stems.  

If you can trim out the rusted leaves and or small stems, that would help reduce the amount of spores in the area.  As the article states, fungicides are a protective chemical that either don't allow the spores to germinate or kills them before they enter the leaf tissue.  They are NOT a curative product and won't eliminate the rust from the leaves or the plant.  I have no idea of a fungicide that you could use for rust -- the label is the law on use of pesticides.  If it is not on the label, you should not use the product.  

Again, keep the plant stress free and growing, trim out if possible the affected leaves, if it needs water then water it to keep the stress down.  Hope this helps.  You might take a sample in to the local county OSU Extension office and ask them for more details.  Don



Hi Again, I forgot to add that you should use caution in watering the shrub/trees.  Moisture will enhance the spores to germinate and infect the leaves.  If you do water, let the hose dribble on the ground around the plants or on the mulch -- don't spray the foliage.  Don