The phytosanitary status of the national collection of fruits and nuts of Afghanistan and the private mother stock nurseries: A virus survey

The horticultural industry is a vital component of the agriculture sector of Afghanistan, the primary engine of the country’s recovering economy which engages approximately 80% of the working population. This sector was thriving in the 1970s, but is today incapable of competing in the international market. To recover and develop the horticulture of the country, the European Community (EC) supports the PHDP (Perennial Horticulture Development Project), to provide true to type/ecotype and healthy planting materials, and the Plant Biotechnology Laboratory, to ensure the health status of local germplasm. This laboratory started screening the health status of the Afghan Germplasm National Collections in order to ensure the multiplication of not only the best-selected varieties or ecotype, but also to avoid production and distribution of virus-infected trees. Inspection for symptoms and sample collection for viral diseases was carried out in all the National Collection fields, including cherry, pear, peach, plum, apricot, almond, apple, grape and citrus plants, located in different areas of the country. Stone fruit plants infected by Apple chlorotic leaf spot virus or Prunus necrotic ringspot virus have been identified in the National Collection experimental farms located in different provinces of Afghanistan. Moreover, many grape plants included in the National Collection located in Herat and Kandahar resulted infected by Grapevine fanleaf virus, but only few imported plants by Grapevine leafroll associated virus 1, Grapevine leafroll associated virus 3 or Grapevine virus A. Finally, in Jalalabad (Nangarhar province) citrus plants showing vein flecking, yellowing and plant decline symptoms were found to be infected by Citrus tristeza virus. Some of the identified viral isolates have been characterized molecularly, amplifying a fragment corresponding to the coat protein gene from a selection of positive samples. The presence of those viruses in different accessions of the national collection is of concern for Afghan horticulture. Implementation of the certification schemes is therefore necessary to quarantine the production and for the employment of virus-free propagating material.