Vulnerable stages of cashewnuts for pest infestation and the pest influence on kernel quality

Abstract

Insect infestation on cashewnuts is mainly due to tea mosquito bug, thrips and apple and nut borers. Developing tender nuts are more vulnerable to the attack by these pests compared to matured nuts. Among the phenological stages, 619, 711 and 713 were highly vulnerable to TMB and ANB, where the infested tender nuts dried and fell down prematurely. Random samples of harvested raw cashewnuts collected from cashew plantations indicated that, among the three pests, thrips infestation was more followed by ANB and TMB. Varied levels of pest infestation resulted differences in physical characteristics of nuts and kernels. But, presence of shrivels, brown patches, black spots on kernels of healthy raw cashewnuts without visible signs of pest infestation indicates involvement of factors other than insects. Less damage of thrips (G1 and G2), ANB (A1 and A2) and TMB on raw cashewnuts had no much influence on the kernel physical quality and highly significant correlations were arrived with good kernel recovery. But, good kernel recovery was very less in G3, G4 and A3 nuts. Percent reduction of nut length, nut width and nut thickness up to 18.13, 8.20 and 6.97, respectively has been recorded in G4 nuts compared to healthy cashewnuts.