Alfalfa (Medicago sativa L.) is cultivated as a forage crop in many countries including Saudi Arabia. Phytoplasma like symptoms on alfalfa were noticed in Alhasa region, Eastern province.
Phytoplasmas were detected in 43/76 alfalfa samples, and from 16/33 batches of all leafhopper species tested. No PCR products were obtained for asymptomatic plant samples. Hence plant samples showing witches broom symptoms and leafhoppers were analyzed by DNA extraction and amplification with phytoplasma-specific primers. The work confirmed that phytoplasmas are infecting alfalfa crop in Alhasa, Saudi Arabia, and the leafhopper species viz. Empoasca decipiens (Paoli) and Cicadulina bipunctata (Melichar) were identified as potential vectors. Vector-host-plant interactions play an important role in determining the spread of phytoplasmas. It is very likely that due to their abundance and capability to carry phytoplasmas, E. decipiens and C. bipunctata mainly contributed to the spread of phytoplasma disease in alfalfa. Further work will be focused on the establishment of important vector(s) of the alfalfa disease, and identification of new alternative hosts with epidemiological implications.
Fig. Alfalfa witches-broom disease cause by phytoplasma showing typical phyllody symptoms. By Khalid Alhudaib.