A YELLOWS DISEASE OF CARAWAY (CARUM-CARVI L) IN CANADA ASSOCIATED WITH AN UNIDENTIFIED PHYTOPLASMA

A phytoplasma-induced yellows disease was discovered on caraway (Carum carvi L.) in southern Alberta and west central Saskatchewan in 1996. Symptoms of leaf reddening, chlorosis, plant stunting, proliferation o f axillary shoots and malformations of floral parts involving virescen ce and phyllody caused by a phytoplasma, were found in research plots at experimental farms near Brooks, Alberta and Outlook, Saskatchewan i n 1996. Transmission electron microscopy and DAPI (4'-6'-diamidino-2-p henylindole) staining revealed phytoplasma bodies in sieve tube elemen ts in diseased planes, but not in healthy ones. The diameter of these bodies ranged from 0.27-0.80 x 0.25-0.50 mu m and averaged 0.63 x 0.45 mu m. Most of the phytoplasma bodies were oval to spherical, lacked c ell walls, and were surrounded by single membranes. This is the first report of a phytoplasma disease of caraway in Canada.