BIO-EFFICACY OF FIPRONIL 200 SC FOR THE CONTROL OF LEAF FOLDER AND YELLOW STEM BORER IN RICE

Transcription

1 BIO-EFFICACY OF FIPRONIL 200 SC FOR THE CONTROL OF LEAF FOLDER AND YELLOW STEM BORER IN RICE * K. Vasanta Bhanu, A. Vishnuvardhan Reddy and P. V. Satyanarayana Andhra Pradesh Rice Research Institute and Regional Agricultural Research Station, Maruteru , West Godavari District, Andhra Pradesh, India *Author for Correspondance ABSTRACT Field experiments were conducted during 2013 to field evaluate the field efficacy of fipronil 200 SC at different dosages i.e. 30, 40 and 50 g a.i./ha in comparison with treated and untreated checks. The results indicated that in both the seasons, all the dosages of fipronil 200 SC significantly reduced the incidence of leaf folder along with the treated checks viz., fipronil 80 WG and fipronil 5 50 g a.i./ha. Fipronil 200 SC also recorded lowest incidence of white ears in both the seasons and dead hearts during. No phytotoxicity symptoms were observed on rice in any of the tested doses. Fipronil g a.i. /ha recorded superior grain yields of 4036 kg/ha during and 3512 kg/ha during at par with check insecticides fipronil g a.i. /ha (4457 kg/ha) and fipronil 5 50 g a.i. /ha (4051 kg/ha) during and 2013 respectively. Key Words: Rice, Fipronil 200 SC, Bio-efficacy, Leaf Folder, Yellow Stem Borer and Grain Yield INTRODUCTION Rice (Oryza sativa L.) is an important staple food crop for more than half of the world population and accounts for more than 50% of the daily calorie intake (Khush, 2005). Approximately 52% of the global production of rice is lost annually owing to the damage caused by biotic stress factors, of which 21% is attributed to the attack of insect pests (Yarasi et al., 2008). Rice is infested by more than 100 species of insects and mites and about 20 of them are considered to be major economic significance. Among the serious insect pests, rice leaf folder (RLF), Cnaphalocrosis medinalis (Guenee) and yellow stem borer (YSB), Scirpophaga incertulas (Walker) are considered to be major lepidopteran pests causing significant yield loss. Rice leaf folder, earlier considered to be minor pests have gained the status of major pests with the wide spread cultivation of high yielding varieties and the accompanying changes in cultural practices. Leaf folder larva fastens the edges of the leaves, folded them longitudinally and feed on green matter. A damaged leaf produce white streaks, become membranous and ultimately reduces the photosynthetic activity of the plant. The extent of loss may extend up to 63 to 80 percent depending on agro-ecological situations (Rajendran et al., 1986). Yellow stem borer larvae after emerging from the egg mass enters in to the tiller and feed inside it and damages the central whorl, resulting into dead heart during vegetative stage and white ears at reproductive stage. Muralidharan and Pasalu (2006) reported that due to 1% dead heart or white ear or due to both phases of stem borer damage would be 2.5, 4.0 and 6.4% yield loss respectively. Farmers still consider application of insecticides as a key component of integrated pest management programme. Hence, fipronil 200 SC a new insecticide is field evaluated for its bio-efficacy against rice leaf folder and yellow stem borer infesting rice. MATERIALS AND METHODS A field experiment was conducted at A.P.R.R.I and R.A.R.S., Maruteru during and The experiment was laid out in a randomized block design with eight treatments and three replications. The varieties Krishnaveni () and Swarna () were sown during the month of July. Seedlings were transplanted 25 days after sowing with a spacing of 20 x 15 cm. All the agronomic practices were followed as per the recommended package of practices. The knapsack sprayer and spray 500 l/ha was used with hollow cone nozzle to impose the spray treatments. The treatments were imposed twice at 55 and 75 days after transplanting (DAT) during and at 50 and 70 DAT during. The insecticide treatments include untreated control, fipronil , 40 and 50 g a.i./ha, fipronil g a.i./ha, fipronil 5 50 g a.i./ha, chlorpyriphos g a.i./ha and L-cyhalothrin g a.i./ha. The observations on number of dead hearts/white ears and total numbers of tillers/panicle from 10 randomly selected hills were recorded for stem borer. The per cent incidence (dead heart/ white ears) was calculated as follows. Number of dead heart/white ears Per cent incidence = X 100 Total number of tillers/panicles 12

2 The damaged leaves due to leaf folder and total leaves from 10 randomly selected hills were recorded in each plot at one day before and five and ten days after each spray in all the treatments. The percentage of leaf damage was calculated as follows. Number of damaged leaves Per cent incidence = X 100 Total number of leaves The data on % leaf folder damaged leaves and % white ears were transformed to Arc Sine values. The grain yields were collected from each net plot and converted to kg/ha. Phytotoxic symptoms such as leaf chlorosis, leaf tip burning, leaf necrosis, leaf epinasty, leaf hyponasty, vein clearing, wilting and rosetting were observed critically from the 20 randomly selected plants at 1, 3, 7, 10 and 15 days after spraying. The extent of phytotoxicity was recorded based on the scale prescribed by Central Insecticides Board and Registration Committee. The data was subjected to statistical scrutiny and the means were separated by least significance difference (Gomez and Gomez, 1984). RESULTS AND DISCUSSION Leaf Folder The results from the table 1 indicated that before the imposition of first insecticide treatments there was no significant difference in % leaf folder damaged leaves among the treatments indicating that the distribution of leaf folder damaged leaves was uniform. At five days after the first spray, the % leaf folder damaged leaves varied significantly among the treatments. Among the treatments, significantly lowest per cent of leaf folder damaged leaves was observed in fipronil g a.i./ha (1.28) and was on par with fipronil 5 50 g a.i./ha (1.56), fipronil g a.i./ha (1.78), fipronil g a.i./ha (1.83) and fipronil g a.i./ha (1.93). At ten days after the first spray, the % leaf folder damaged leaves varied significantly among the treatments. Among the treatments significantly lowest per cent of leaf folder damaged leaves was observed in fipronil 5 50 g a.i./ha (1.15) and was on par with fipronil g a.i./ha (1.33), fipronil g a.i./ha (1.40), fipronil g a.i./ha (1.44) and fipronil g a.i./ha (1.81). Table 1: Comparative efficacy of Fipronil 200 SC on the incidence of leaf folder during kharif 2012 % Leaf folder damaged leaves* S. No. Particulars of the treatments Dose in g a.i/ha 1 st spray 2 nd spray BS BS BS BS 5 1. Untreated control (10.42) (23.70) (23.70) (23.70) (35.41) 2. Fipronil 200 SC (10.90) (15.59) (15.59) (15.59) (14.15) 3. Fipronil 200 SC (11.59) (14.43) (14.43) (14.43) (14.85) 4. Fipronil 200 SC (11.46) (14.32) (14.32) (14.32) (14.63) 5. Fipronil 80 WG (10.19) (14.66) (14.66) (14.66) (14.56) 6 Fipronil 5 SC (10.81) (15.80) (15.80) (15.80) (15.15) 7 Chlorpyriphos 20 EC (10.59) (20.81) (20.81) (20.81) (27.75) 8 L-cyhalothrin 4.9% CS (10.78) (20.96) (20.96) (20.96) (26.13) F test -- NS Sig Sig Sig Sig Sig C.D. (0.05) (43.24) 6.33 (14.57) 7.20 (15.56) 6.92 (15.26) 6.78 (15.09) 6.15 (14.24) (37.51) (32.46) CV (%) *=Figures in parenthesis are arc-sine transformed values; BS= Before spray, = Days after spray 13

3 During second spray (table 1) the leaf folder incidence was increased. Before the second spray, the % leaf folder damaged leaves varied significantly among the treatments. Among the treatments significantly lowest per cent of leaf folder damaged leaves was observed in fipronil g a.i./ha (6.14) and was on par with fipronil g a.i./ha (6.23), fipronil g a.i./ha (6.41), fipronil g a.i./ha (7.23) and fipronil 5 50 g a.i./ha (7.50). At five days after the second spray, all the fipronil treatments viz., fipronil , 40 and 50 g a.i./ha, fipronil g a../ha and fipronil 5 50 g a.i./ha recorded significantly lowest per cent of leaf folder damaged leaves ranged from 5.99 to 6.88 % and superior to check insecticides. Similar trend was observed at ten days after second spray also. The results from the table 2 indicated that before the imposition of first insecticide treatments there was significant difference in % leaf folder damaged leaves among the treatments. L-cyhalothrin 4.9% 12.5 g a.i./ha (1.04) recorded significantly high per cent of leaf folder damaged leaves than other treatments. At five days after the first spray, the % leaf folder damaged leaves varied significantly among the treatments. Significantly lowest per cent of leaf folder damaged leaves was observed in fipronil g a.i./ha (0.86) and on par with fipronil 5 50 g a.i./ha (0.92), fipronil g a.i./ha (1.01), fipronil g a.i./ha (1.04) and fipronil g a.i./ha (1.23). The check insecticides viz., chlorpyriphos g a.i./ha (2.13) and L-cyhalothrin g a.i./ha (2.25) recorded highest per cent of leaf folder damaged leaves and on par with untreated control (2.72). At ten days after the first spray also the % leaf folder damaged leaves varied significantly among the treatments. Significantly lowest per cent of leaf folder damaged leaves was observed in fipronil g a.i./ha (0.20) and was on par with fipronil 5 50 g a.i./ha (0.22). These were followed by fipronil g a.i./ha (0.48), fipronil g a.i./ha (0.54) and fipronil g a.i./ha (0.76). The check insecticides viz., chlorpyriphos g a.i./ha and L-cyhalothrin g a.i./ha and untreated control recorded highest per cent of leaf folder damaged leaves. Table 2: Comparative efficacy of fipronil 200 SC on the incidence of leaf folder during kharif 2013 % Leaf folder damaged leaves* Dose S. Particulars of the 1 st spray 2 nd spray (g No. treatments a.i/ha) BS BS 1. Untreated control (3.77) (9.48) (6.34) (4.35) (21.58) 2. Fipronil 200 SC (5.03) (5.73) (4.92) (3.33) (8.45) 3. Fipronil 200 SC (2.94) (5.78) (2.09) (2.25) (7.33) 4. Fipronil 200 SC (3.82) (5.30) (4.22) (1.92) (6.25) 5. Fipronil 80 WG (3.80) (6.32) (3.81) (2.16) (7.99) 6 Fipronil 5 SC (4.29) (5.12) (2.21) (2.25) (8.68) 7 Chlorpyriphos 20 EC (4.61) (8.27) (6.80) (4.3) (21.53) 8 L-cyhalothrin 4.9% CS (5.86) (8.60) (6.93) (5.77) (19.49) F test -- Sig Sig Sig Sig Sig Sig C.D. (0.05) (17.67) 0.83 (5.12) 0.96 (5.56) 0.72 (4.80) 0.40 (2.74) 0.43 (3.01) 9.28 (17.74) 8.25 (16.46) CV (%) *=Figures in parenthesis are arc-sine transformed values BS= before spray, = Days after spray During second spray, the % leaf folder damaged leaves varied significantly among the treatments at all the observations recorded. Before spray, L-cyhalothrin g a.i./ha (1.01) recorded significantly highest per 14

4 cent of leaf folder damaged leaves. At five days after the second spray, significantly lowest per cent of leaf folder damaged leaves was observed in fipronil g a.i./ha (1.19) and on par with fipronil g a.i./ha (1.69) and fipronil g a.i./ha (1.94). These were followed by fipronil g a.i./ha ( 2.16%) and fipronil 5 50 g a.i./ha (2.32). The check insecticides viz., chlorpyriphos g a.i./ha (13.50) and L-cyhalothrin g a.i./ha (11.20) recorded highest per cent of leaf folder damaged leaves and on par with untreated control (13.53). At ten days after the second spray, all the fipronil treatments viz., fipronil , 40 and 50 g a.i. /ha, fipronil g a.i./ha and fipronil 5 50 g a.i./ha recorded significantly lowest per cent of leaf folder damaged leaves ranged from 0.40 to 0.96 % and superior to check insecticides. Yellow Stem Borer The incidence of yellow stem borer was not observed during vegetative stage and moderate at reproductive stage (Table 3). All the treatments recorded significantly lower % of dead hearts than untreated control. (10.87%) The difference in % dead hearts among the insecticide treatments was significant. Significantly lowest % dead hearts was observed in fipronil g a.i. /ha (2.78%) and was on par with fipronil g a.i. /ha (2.91%) and fipronil g a.i. /ha (3.16). These were followed by fipronil 5 50 g a.i. /ha (4.36) and were superior to check insecticides viz., chlorpyriphos g a.i./ha (7.07%) and L-cyhalothrin g a.i./ha (6.43%). The incidence of yellow stem borer was low during vegetative stage and moderate at reproductive stage (Table 3). The differences in per cent dead hearts among the treatments were not significant before first spray. At five days after the first spray, except chlorpyriphos g a.i./ha (3.04), remaining insecticide treatments recorded significantly lower % of dead hearts than untreated control (3.38). Among them, fipronil 5 50 g a.i./ha recorded lowest per cent of dead hearts (0.84) and on par with all the dosages of fipronil 200 SC, fipronil g a.i/ha and L-cyhalothrin 4.9% 12.5 g a.i./ha. Table 3: Comparative efficacy of fipronil 200 SC on the incidence of yellow stem borer and grain yield during kharif 2012 and 2013 % Dead hearts* % white ears Grain Yield (kg/ha) Dose S. Particulars of the (g kharif 2013 No. treatments kharif kharif kharif kharif a.i/ha) 5 10 BS Untreated control (4.94) (10.59) (9.69) (19.24) (18.45) Fipronil 200 SC (7.80) (6.44) (5.34) (13.10) (14.10) Fipronil 200 SC (2.15) (5.25) (3.96) (9.65) (10.63) Fipronil 200 SC (10.47) (5.33) (8.73) (9.51) (13.00) Fipronil 80 WG (4.89) (6.80) (8.59) (10.15) (10.15) Fipronil 5 SC (2.18) (5.19) (5.37) (12.05) (12.27) Chlorpyriphos EC (9.76) (10.03) (9.83) (14.64) (11.35) L-cyhalothrin 4.9% CS (2.82) (6.49) (4.97) (15.40) (11.01) 2366 F test NS Sig Sig Sig Sig Sig Sig C.D. (0.05) CV (%) *=Figures in parenthesis are arc-sine transformed values BS= before spray, = Days after spray 15

5 The difference in % dead hearts among the insecticide treatments was significant at ten days after first spray also. Significantly lowest % dead hearts was observed in fipronil g a.i. /ha (0.64) and was on par with fipronil g a.i. /ha (0.89) and fipronil 5 50 g a.i./ha (0.90). These were followed by L-cyhalothrin 4.9% 12.5 g a.i./ha (1.01), fipronil g a.i. /ha (2.60) and fipronil g a.i. /ha (2.60) and were superior to check insecticide viz., chlorpyriphos g a.i./ha (3.35) and untreated control (2.93). Before harvest, the data on per cent white ears indicated that all the insecticide treatments recorded significantly lowest per cent than untreated control (10.16). Among the insecticide treatments, fipronil g a.i. /ha recorded lowest per cent of white ears (3.42) and on par with other insecticides. Grain Yield The differences in grain yield among the treatments were significant. Among the treatments, fipronil g a.i. /ha (4457 kg/ha) and fipronil g a.i. /ha (4036 kg/ha) recorded significantly superior grain yields than treated checks chlorpyriphos g a.i./ha (2945 kg/ha), L-cyhalothrin g a.i./ha (3409 kg/ha) and un treated control (2521 kg/ha) (Table 3). The differences in grain yield among the treatments were significant. Among the treatments, fipronil 5 50 g a.i. /ha (4051 kg/ha) recorded significantly superior grain yields and followed by fipronil g a.i. /ha (3512 kg/ha) and fipronil g a.i./ha (3397 kg/ha) (Table 3). Phytotoxicity None of the insecticidal treatments showed any type of phytotoxic symptoms on rice at all the dosages tested. The overall results indicated that among all the dosages of fipronil 200 SC; the 50 g a.i./ha were found to be effective in controlling leaf folder, yellow stem borer along with the check insecticides viz., fipronil g a.i./ha, fipronil 5 50 g a.i./ha and recorded higher grain yields. The efficacy of fipronil 200 SC on leaf folder and yellow stem borer was not reported elsewhere in the literature. However, the efficacy of fipronil 80 WG (Mahal et al., 2008) and fipronil 5 SC (Dhaka et al., 2011) was reported earlier. REFERENCES Dhaka SS, Prajapathi CR, Singh DV & Singh R (2011). Field Evaluation of Insecticides and Bio-Pesticides against Rice leaf folder, Cnaphalocrocis medinalis (Guenee). Annals of Plant Protection Sciences, 19(2) Gomez KA & Gomez AA (1984). Statistical Procedures for Agricultural Research, John Wiley and Sons, New Delhi Khush GS (2005). What it will take to feed five billion rice consumers by Plant Molecular Biology, Mahal MS, Sarao PS & Singla ML (2008). Bioefficacy of Fipronil 80 WG for the control of Stem Borer and Leaf Folder in Basmati Rice. Indian Journal of Plant Protection, 36(2) Muralidharan K & Pasalu IC (2006). Assessments of crop losses in rice ecosystems due to stem borer damage (Lepidoptera: Pyralidae). Crop Protection, Rajendran R, Rajendran S & Sandra PC (1986). Varietals resistance of rice of leaf folder. International Rice Research News, Yarasi B, Sadumpati V, Immanni CP, Vudem DR & Khareedu VR (2008). Transgenic rice expressing Allium sativum leaf agglutinin (ASAL) exhibits high-level resistance against major sap-sucking pests. BMC Plant Biology,