The shot has grown from the rootstock and needs to be removed either by pulling or cutting off at or below ground level.

To check if the scion is still alive scrape away a little of the bark with a finger nail if it looks green underneath your tree is okay. Otherwise it is dead, by this time of year it should be in full leaf.

If the main part is still plump and green underneath, try watering with a few gallons of weak sugar solution, about 2 tablespoons of white sugar per gallon. That frequently gives it the energy to kick out new shoots.