(Asghari Tazehkand et al. 2006), as well as in
ornamental and weed plants (Babaie et al. 2007),
and in cherries (Zirak et al. 2006). A 16SrI-A subgroup
phytoplasma has been detected in black-eyed
susan phyllody (Babaie et al. 2007).
We conclude that phytoplasmas of the Aster yellows
(16srI) group are involved in the Russian olive witches’
broom disease we detected in Urmia and Tehran
provinces. Our limited analysis suggests that ROWBp-
U and ROWBp-T are indistinguishable from a phytoplasma
in Alfalfa with witches’ broom symptoms. This
confirms that 16SrI phytoplasmas are widespread in Iran,
and are hosted by several plant species (Babaie et al.
2007), and the possibility that alfalfa may present a
reservoir of the phytoplasma cannot be ruled out. Since
2003, the occurrence of ROWBp has gradually
increased in the Urmia region and currently 4% of trees
are infected. No weed reservoir of the pathogen was
identified in our surveys. ROWB symptoms were also
observed in the trees grown in the Eastern Azarbaijan
(Zamharir and Mohammadipour 2007) and Arak.
All these results together show that the disease is a
threat for the cultivation of Russian olives. Although
a number of specific phytoplasma vectors have been
detected in Iran (Siampour et al. 2004), nothing is
known about the presumed leafhopper that transmits
phytoplasmas to Russian olive and, probably, alfalfa.
A preliminary report of our work has appeared
(Rashidi et al. 2006).
Acknowledgements We would like to thank Dr. Robert G.
Milne, Dr. Cristina Marzachi and Dr. Nuredin Habili for
critically reading the manuscript.