Relationship between the levels of infestation of Xylosandrus crassiusculus Motschulsky (Coleoptera: Scolytidae) and growth parameters of grape

The present field studies were carried out on untreated grape orchard cv. Bangalore Blue at Nagadasanahalli, Bangalore (North) (12°58’N; 77°35’E), Karnataka, India to know the relationship between the infestation level of scolytid, Xylosandrus crassiusculus Motschulsky and growth parameters of grape vine. Similar studies were also carried out on treated grape orchard at Indian Institute of Horticultural Research, Bangalore. The number of scolytid damaged holes on the main trunk was significantly and negatively correlated with total number of bud sprouts. This implied that as the infestation levels of scolytids increased on the vine trunk, the number of sprouts produced by the vines after pruning reduced. Similarly, as the number of sprouts decreased with the severity of the shot hole borer infestation, the number of bunches per vine also decreased. However, within a bunch, the number of berries, which directly contributed to the weight of the bunch, was not affected. But overall productivity was affected. From the study carried out at the Indian Institute of Horticultural Research vineyard, where control measures were taken immediately after noticing the shot hole borer attack on the trunks by regular and close monitoring of pest attack, the growth and development of the vines and yield (number of bunches) were not affected.