Phytopathogenic Mollicutes

Among the cultivated forage crops, alfalfa is very important in Iran. Nearly 28 years ago, symptoms of alfalfa witches’ broom (AWB) were reported from Jiroft, southern of Iran. Since then, the disease was reported from other parts of Iran and the epidemic of AWB was recorded in Chahgeer, Yazd in 1997. Now AWB disease is widespread all over the country especially in tropical and subtropical areas. The phytoplasma strains reported from alfalfa in Iran were classified in 16SrI, 16SrII, 16SrVI and 16SrXII groups. The major symptoms reported are little leaf, internode shortening, flower virescence, phyllody, proliferation and sterility, witches'broom, leaf yellowing, leaf curling and death. Orosius albicinctus was identified as vector of the disease in Fars and Yazd provinces. Prosopis farcta and Cardaria draba were natural host plants of the AWB. The disease reduced plant heights, leaf area, shoot dry and fresh weight and seed yields of alfalfa crops. So far no effective control strategies are in practice; however use of dense planting and field resistant varieties are recommended for prevent ing AWB disease.