Grape - The fruit is falling off ?
District of Columbia
We viewed your photo and cannot say for sure what is going on.
Grapes do not demand a lot of fertilizer and do not have a problem finding nutrients. Grapes do best in soils that range in pH from 5.8 to 6.8. Do not over fertilize. Testing your soil test will give you pH and nutrient deficiencies. http://extension.umd.edu/hgic/soils/soil-testing
Also, grapes usually start to bear three years from planting to first crop. The grapes may have been immature. Be patient.
Here is our website on grapes including fertilizing information. http://extension.umd.edu/hgic/grapes