Experimental set-ups
From each tree, two (pear and peach) or four (apple) mature leaves were
selected. The mass flow measurements were done in vivo .
Thereafter the leaves were cropped, length and width of the leaf lamina
were measured, cross sections were done to analyse the mass flow rate,
the middle part of the midrib was fixed in a fixative and the rest of
each leaf was used for phytoplasma titer determination. Leaves for
phytohormone measurements were separately collected, immediately frozen
in liquid nitrogen and stored at -20 °C until used.