Figure 4.

Autofluorescence in (a) healthy; (b) chlorotic; and (c) necrotic needles from Pinus radiata. Sequential excitation at 355, 488, and 633 nm with corresponding emission at 400–500 (blue), 500–570 (green), and 650–750 nm (red). Note the absence of resin canals in these three needles from the same tree. Fluorescence associated with ferulate is also absent from the phloem in these needles. Both features were found to be variable. Scale bar = 200 μm.