Translocation moves sugar from a source to a sink via phloem.
- Loading of sugar into the sieve tube at the source
reduces water potential inside the sieve-tube.
This causes the tube to take up water by osmosis.
- Uptake of water generates positive pressure that forces the
sap to flow along the tube.
- The pressure is relieved by the unloading of sugar and water
from the tube at the sink.
- Xylem recycles water from sink to source.
Translocation in summer: 
Translocation in spring: