Field setup (A) and a typical measurement (B). The phloem turgor pressure probe was developed from the state of the art cell pressure probe with some modifications (see Methods). With a special holder, it can be easily installed and manipulated. By rotating the nut of the screw micrometer, a relaxation is made to adjust the sap/oil boundary and a distinct turgor pressure fall (spikes in the Figure 2B) could be identified. However, maintaining the meniscus at the position, the phloem turgor pressure could quickly recover to its former value. By this mean, the probe blockage and the measured pressure could be verified. If coagulation is identified, a new puncture will be required (the pressure measurement interruption in the Figure 2B).