| Abstract |
An experiment was conducted on ‘Horticultural mineral oil for the management of pests in mango during the vegetative phase’ was conducted during 2023-2024 at college of agriculture, Padannakkad and Instructional Farm II, Karuvachery. The objective of the study was to evaluate of Horticultural Mineral Oil (HMO) for the management of mango pests at the vegetative phase. The laboratory experiments were carried out in the Department of Entomology, College of Agriculture, Padannakkad. In the phytotoxicity evaluation, various concentrations of HMO (T1: 3.0%, T2: 3.5%, T3: 4.0%, T4: 4.5%, T5: 5.0%, T6: 5.5%, T7: 6.0%, T8: 6.5%, T9; 7.0%, T10; 8.0%, T11; 9.0% and T12; control) were tested on one year-old mango (Neelum) grafts, revealed that there were no signs of phytotoxicity symptoms up to T8. However, higher concentrations particularly T9, T10 and T11 caused symptoms like necrosis and chlorosis. Based on these findings, four higher concentrations viz., 5.0%, 5.5%, 6.0% and 6.5% were selected for laboratory bioassay. To evaluate the repellency against feeding and oviposition of leaf cutting weevil (Deporaus marginatus), HMO at a concentration of 6.5% effectively reduced feeding, with a recorded feeding area of 3.28 cm² and 63.47% reduction in feeding area compared to the control at 24 hours after treatment (HAT), which was on par with HMO at 6.0%. In all treatments, no oviposition by leaf-cutting weevils was observed. Evaluation of HMO against adults of leaf cutting weevil under laboratory conditions showed that HMO at a concentration of 6.0% and 6.5% caused 64% and 88% mortality of leaf cutting weevil respectively, at 24 HAT in residue film test. In spraying method, HMO at 6.0% and HMO at 6.5% had showed 72% and 76% mortality of leaf cutting weevil respectively, at 24 HAT. When HMO was evaluated against leaf cutting weevil grubs, at a concentration of 6.0% and 6.5% achieved 100% mortality at 24 HAT. Since the results for 6.0% and 6.5% were statistically similar, these two concentrations were selected for field studies. Field evaluation of HMO was carried out at Instructional Farm II, Karuvachery, College of Agriculture, Padannakkad under Randomized Block Design with seven treatments and four replications. The treatments were T1: HMO 6.0%, T2: HMO 6.5%, T3: Pongamia oil soap, T4: Neem oil-garlic soap, T5: Chlorantraniliprole 18.5 % SC, T6: Acephate and T7: Control. Observations on the mean number population of leaf cutting weevil indicated that T6, T3, T5 and T2 were more effective in reducing the mean population during the first application of treatments and it was on par with each other. During the second and third application of treatments, T6, T3 and T5 effectively reduced the mean population of leaf cutting weevils, which were statistically similar with T2 and T1. There was an effective reduction in the mean number of scraped leaves caused by leaf cutting weevil with T6 (3 DAT and 5 DAT in the first application of treatments) and T3 (7 DAT and 9 DAT), which were on par with other treatments. During the second and third application of treatments, T5 and T2 were observed more effective in reducing mean damage and were on par with each other. T1 and T2 were found to be effective in reducing mean number of cut leaves during the first and second application of treatments, which was on par with T3, T5 and T6. There was an effective reduction in mean number of fallen tender leaves from plant base by T3 (9 DAT) and T2 (3 DAT, 5 DAT, 7 DAT and 9 DAT) during the first and second application of treatments, respectively, which were on par with other treatments. For ash weevil (Myllocerus discolor), T6 was found to be effective in controlling the mean number population during the first application of treatments, which is statistically similar with T3 and T2. A similar trend of the population was followed till 9 DAT during the second and third application of treatments, which were on par with T3 and T2. Observations on mean number of damages indicated that T6 was effective in reducing the mean damage during the first (3 DAT, 5 DAT, 7 DAT and 9 DAT) and second (7 DAT and 9 DAT) application of treatments and it was on par with T1, T2 and T3. During the third application of treatments, T2 was effectively reduced the mean number of damaged leaves, which was on par with other treatments. In all three applications of treatments, HMO was effective in controlling the mean number of population and mean number of damages of both leaf cutting weevil and ash weevil and was found to be statistically similar with T6.
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