Citrus, especially Omani lime, is one of the most important fruit trees in the Sultanate of Oman in terms of production and cultivated area. Acid lime is cultivated in most parts of the country, especially in the northern part of the Sultanate. Citrus has faced various challenges over the past decades, of which the most important was witches’ broom disease that killed nearly a million lime trees.
Dr. Abdullah Mohammed Al-Sadi, a Plant Pathologist and Dean of the College of Agricultural and Marine Sciences at Sultan Qaboos University said that the research team at the college noticed the presence of symptoms of a disease on Omani limes in some areas of the country. “The symptoms are characterized by yellow veins, blotchy mottled patterns on leaves, small green fruits, lopsided fruits, half green fruits, yellow shoots, twig dieback, and tree decline. Examination of the symptoms by our MSc student Ahmed Al-Fahdi proved infection of the trees by the Asian strain of causal agent of citrus greening disease, a bacterium called Candidatus Liberibacter asiaticus. The disease was observed in some farms in Sohar, Al Rustaq, Al Jabal Al Akhdar, Salalah and other areas”, he said.
Dr. Abdullah Al-Sadi added that the disease is called Citrus greening or Huanglongbing disease (yellow dragon disease). Greening disease is one of the most serious diseases that threaten citrus production in the world. The disease first originated in China and it was then reported in other countries including Brazil, USA, India, Saudi Arabia and others.
“It is important to do more surveys to investigate distribution of the disease in other areas of the country. If the disease is not widespread in the Sultanate, it may be necessary to eradicate the infected trees”, the Dean observed.