Fine Structure Analyses of Stem Nematode-Induced White Flagging in Medicago sativa

W. F. Campbell, G. D. Griffin


White flagging of alfalfa, Medicago sativa 'Ranger, found associated with Ditylenchus dipsaci in the Columbia River Basin was observed in northern Utah during 1971. This is a report on chloroplast changes, induced by D. dipsaci in alfalfa leaves, as observed with an electron microscope. Leaves from alfalfa plants infected with D. dipsaci were either devoid of normal pigmentation or displayed various shades of yellow-green. Cells of leaf tissue from noninfected plants exhibited normal chloroplast structure. By contrast, the chloroplast structure in cells of leaf tissue from infected plants showed progressive degradation as normal pigmentation decreased. Key Words: Alfalfa, electron microscope, injury, pigmentation.

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