Screening of okra, Abelmoschus esculentus L. (Moench) germplasm collections against two spotted spider mite, Tetranychus urticae (Koch) based on damage grading index

Abstract

The investigation on screening forty one germplasm collections of okra for their reaction against two spotted spider mite Tetranychus urticae (Koch) by damage grading index and mean mite population/cm2 expressed a diverse reaction among the tested entries. The results revealed that the entry viz., IC 117238 which recorded mean mite population of 35.6 /cm2 leaf area was found to be highly susceptible to TSSM with the damage rating of four (0-4 Scale). The seven highly resistant okra germplasm collections (IC 128092, IC 128095, EC 305743, EC 306737, IC 031850, IC 105742 and IC 117235) which recorded the minimum mite population ranging between 13 and 15.67/cm2 leaf area were categorized under the grade zero and could be exploited in developing a resistant source against two spotted spider mite Tetranychus urticae.

Keywords

• screening
• okra germplasm
• damage grading index
• tetranychus urticae