Dynamics of emergence and spread of citrus huanglongbing disease in Iran

Huanglongbing or Fruit Greening is one of the major citrus diseases in Iran that has spread to most of the country's citrus growing provinces. In this study, the prevalence trend of the disease in seven provinces was investigated and analyzed.

Citrus orchards in Sistan-Balochestan, Hormozgan, Bushehr, Khuzestan, Fars, Kerman and Mazandaran provinces were visited and samples suspected of having this disease were collected, in 2007-2009 and 2017-2019 years. After DNA extraction from the samples, the PCR test was performed using the specific primers OI1/OI2c and A2/J5.

It was found that the percentage of infected specimens, infected areas and number of hosts of Candidatus Liberibacter asiaticus, the causative agent of this disease, has increased over this period. At the end of this period, some samples of oranges, tangerines, grapefruits, bitter oranges, Lisbon lemons and Mexican limes were obtained from the provinces: Kerman, Hormozgan, Sistan-Baluchestan, and Fars were infected with the disease.

The study of the disease during these years showed that: the infected areas and the host range of the disease have expanded a lot during this period, and the spread of the disease in citrus cultivation areas in the south of the country has been with a gentle slope. The reduction of the disease-carrying psyllium population during these years seems to have been effective in slowing down the spread of the disease.