Detection of Major Soil-Borne Viruses and Assessment of Virus-Vector Association in Potato Growing Areas of North-Western Pakistan (Khyber Pakhtunkhwa) and Azad Jammu and Kashmir

Soil-borne potato viruses are an increasing economic threat to crop yield in the future. Potato mop-top virus (PMTV) and Tobacco rattle virus (TRV) and their vector association in field infection in North-western region of Pakistan and Azad Jammu and Kashmir were surveyed in this study. Incidence and distribution of these soil-borne viruses were estimated by field sample collection from Malakand and Hazara divisions of KPK and selected areas of Azad Kashmir. PMTV incidence was 22% in Malakand (highest of 40% in Swat II and Swat V), 24% in Hazara (highest 50% in Galliyat), and 23% from selected areas of Azad Jammu and Kashmir (AJK) (Highest with 40% in Rawalakot and Trarkhal). TRV incidence was 49% in AJK (100% highest field incidence in Khaigala Rawalakot), 53% in Malakand division (80% highest field incidence in Swat II), and 24% in Hazara division (70% highest field incidence in Abbottabad and Mansehra districts). PMTV, TRV vectors are Spongospora subterranea and Trichodorus, Paratrichodorus spp. were found distributed in all surveyed areas. Eighty percent (80%) fields were found infested with S. subterranean, while Trichodorus and Paratrichodorus were found in 64% in Malakand. In Hazara, 84% of surveyed fields were found infested with S. subterranea while 65% were found to be infested with Trichodorus, Paratrichodorus. In AJK S. subterranea was found distributed in 79% of fields. A significant relationship (P value=0.000) between viruses (PMTV and TRV) and their respective vectors were detected in proportionate. The corresponding R2 (0.70 and 0.82) indicates positive relation between viruses and their vectors. Positive Pearson correlation was found among incidence and severity of virus infection (PMTV and TRV) and vectors (S. subterranea; Trichodorus minor, Paratrichodorus), indicating increased disease severity with vector presence and activity. The study will be a tool in vector virus management to economical potato harvest