Question
My young hollies had some black spots , then curling leaves, now  all leaves  are brown and dry but not falling yet.I tried a soap to rid of aphids etc. trying to use only organic treatments, but now I am worried.  help?

Answer
Sounds like a fungi called leaf spots. The soap will not have any effect on the fungi. There are several leaf spots which occur on holly. Of these, tar spot is the most severe. This fungus disease may occur at any time during the growing season; however, it is more prevalent during the moist, cool periods of early spring.

You will need to apply a fungicide to the holly foliage.  Several applications of a broad spectrum fungicide such as maneb, ferbam or a copper fungicide, such as Bordeaux mixture will control the fungi. I would apply about every two weeks for three application.  When possible, diseased leaves should be gathered and destroyed.

If it is aphids the leaves would be sticky with a secretion called honeydew. A sooty mold will grow on this honeydew turning the leaves black. If there is no sticky leaves then it is not aphids.