COMBATING SUNFLOWER NECROSIS DISEASE: INSECTICIDAL STRATEGIES FOR DISEASE SUPPRESSION AND YIELD ENHANCEMENT

Abstract

Sunflower necrosis disease (SND), caused by Tobacco streak virus (TSV), is a major constraint to sunflower production, with thrips facilitating disease transmission through virus-contaminated pollen. A field experiment was conducted at the Zonal Agricultural Research Station, GKVK, Bengaluru, during 2023 and 2024 to evaluate the efficacy of selected insecticidal treatments in managing SND and improving seed yield. Seven treatments were evaluated in a Randomized Complete Block Design (RCBD) with three replications using the susceptible sunflower hybrid KBSH-44. The treatments comprised seed treatment with Imidacloprid  600 FS @ 5 ml kg⁻¹ seed followed by foliar applications of different insecticides at 30, 45 and 60 days after sowing, along with an untreated control. Among the treatments, Imidacloprid  seed treatment followed by foliar sprays of Diafenthiuron 50 WP @ 1 g l⁻¹ was found most effective, recording the lowest disease incidence of 9.25 and 5.34 per cent during 2023 and 2024, respectively, with a pooled mean of 7.29 per cent. This treatment achieved the highest disease reduction (66.89%) over the untreated control and recorded the maximum pooled seed yield (2258.50 kg ha⁻¹), representing a 27.24 per cent yield increase. The next effective treatment was Imidacloprid  seed treatment followed by foliar sprays of Imidacloprid 17.8 SL @ 0.5 ml l⁻¹, which recorded 8.66 per cent pooled disease incidence and 2216.50 kg ha⁻¹ seed yield. The untreated control recorded the highest pooled disease incidence (22.02%) and lowest seed yield (1775.00 kg ha⁻¹). The findings demonstrated that Imidacloprid seed treatment combined with Diafenthiuron foliar applications was an effective insecticidal strategy for reducing sunflower necrosis incidence and enhancing seed yield under field conditions.