I have a sour cherry tree in my yard that declines a bit more each year. It is in sad shape, with seared-open main branches injured by sun scald and invaded by decay fungi. This all stemmed from leaf loss due to an ongoing and pervasive case of brown rot caused by the fungus Monilinia. This organism infects first through the flowers, usually after a rain while the flowers are open.
Now is the time when nurseries are propagating plants for the upcoming spring season. Odd looking plants with too many shoots or buds could be infected with the pathogenic bacterium Rhodococcus fascians. Propagators should be alert for symptoms, as shown in the gallery below, and have suspicious plants tested for the presence of the bacteria.