This could be a type of scale insect (a sap-sucking insect) residing on the leaves of your cherry tree. The blobs may be a cluster of eggs beneath white waxy fibres. I would treat them as soon as possible as they will affect the general health of the plant. Its best to spray the affected areas with a chemical control there are many available. Look for the ingredients Deltamethrin or Thiacloprid on the container and check they are ok to use on fruit trees (if you are growing the tree for edible fruit). You can also buy winter washes which are applied when the tree is dormant to control over-wintering young nymphs.