Abstract
Aim:
This study aimed to evaluate the relative field-efficacy, natural enemies
safety and phytotoxicity of premixed soil insecticide formulation Virtako 1.5
Gr (Chlorantraniliprole 0.5% + Thiamethoxam 1%) against onion thrips (Thrips
tabaci) and black cutworm (Agrotis ipsilon) infesting onion.
Methodology: Two field experiments were conducted in successive
years (2017-18 & 2018-19) to evaluate the bio-efficacy of Virtako 1.5®
Gr against thrips, cutworms and natural enemies in onion. The desired dosage
of Virtako 1.5® Gr was applied as soil broadcasting after 10 days
of transplanting. Thrips population, cutworm damage, natural enemies and
phytotoxicity observation were made using standard procedures.
Results:
The results revealed that Virtako® 1.5 Gr applied @ 105 and 90 g
a.i ha-1 recorded the lowest mean thrips population, 18.03 and
19.50 thrips per plant, respectively. Similarly, Virtako 1.5 Gr at 105 a.i.
ha-1 reduced cutworm damage by 88.5%, followed by Virtako 1.5 Gr
at 90 g a.i. ha-1 (85.5%). Although no natural enemies’ activity
(Coccinellids, Orius spp, and Spiders) was found in the early phase of
onion growth, they were recorded in all treatments at later crop growth
stages. All doses of Virtako 1.5 Gr had no noticeable phytotoxicity effects
on onion plants.
Interpretation: Application of
Virtako 1.5 Gr effectively minimized thrips population and cutworm damage in
onions. Further, it did not show any significant harmful impact on the
activity to above-ground natural enemies. Therefore, Virtako 1.5 Gr at a
lower effective dose 90 g a.i ha-1 can be recommended for onion
against thrips and black cutworm.
Key words: Cutworm, Onion
thrips, Premixed insecticide, Phytotoxicty, Virtako 1.5 Gr
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