Economic losses due to infection by apple scar skin viroid in Himachal Pradesh, India.

Apple scar skin viroid (ASSVd), the type member of the genus Apscaviroid, induces symptoms only on fruits, which include colour dappling, russeting, cracking and distortion. Studies on viroid incidence were conducted during past five years and incidence up to 90.0 percent was recorded in commercial apple cultivars (Royal Delicious, Red Delicious, Red Gold, Golden Delicious). From 2015 to 2018, forty apple orchards were surveyed in different blocks of Shimla district of Himachal Pradesh and fruits in six orchards were found with typical symptoms of apple scar skin viroid infection without symptoms on leaves. The presence of ASSVd in symptomatic fruits and symptomless leaves were confirmed by RT- PCR. It was also revealed that ASSVd infection not only deteriorate the quality of apple fruits but cause large losses in term of yield, as 17.80 quintal less fruit production was recorded in the affected orchards with loss in net return up to Rs. 3,91,102/- per hectare (72.68% loss in net return per hectare).