Evaluating the response of insecticides and fungicides for rind blemishes management in Kinnow mandarin (Citrus nobilis Lour × Citrus deliciosa Tenora) fruits caused by biotic factors

Abstract

Kinnow mandarin being produced in Pakistan faces different quality issues ending up in poor rind quality bearing blemishes on the peel. The main reason behind quality issues is inadequate production management including unoptimized production technology with an inappropriate spray schedule of insecticides and fungicides. Major blemishes found on the surface of fruit are biotic in nature (diseases and insects) and generally appear during the early 8-12 weeks of fruit setting. The objective of this study was to optimize insecticides and fungicides to manage rind blemishes in ‘Kinnow’ mandarin fruits caused by biotic factors. The present study was conducted during 2017-2018; there were four kinds of pesticides such as Actara (Thiamethoxam) or Confidor (Imidacloprid) and Nativo (Tebuconazole and Trifloxystrobin) or Topsin M (Thiophanate-methyl) sprayed to the trees at onset of fruit setting. The extent and nature of blemishes related to diseases and insects were significantly reduced after the spray of 0.3 g L-1 Nativo, 1.5 ml L-1 Confidor as compared to the application of Actara (0.24 g L-1 water) and Topsin M (2 g L-1 water), while the higher extent of blemishes was recorded in control block. Surface smoothness and peel colour of fruits showed significant improvement in sprayed trees compared to control. Likewise, preharvest sprays reduced the post-bloom and commercial fruit drop, resulting in a high yield per tree. However, the preharvest sprays showed a non-significant effect on organoleptic quality and biochemical attributes of ‘Kinnow’ fruit. Conclusively, the combination of Confidor (1.5 ml L-1 water) and Nativo (0.3 g L-1 water) sprays at fruit setting stage could be helpful in managing biotic blemishes in ‘Kinnow’ mandarin fruits resulted in an increased proportion of A-grade quality fruits in final pack out.