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K. PULLAM RAJU*, P. RAJASEKHAR, C.P.D. RAJAN AND N. C. VENKATESWARLU
Department of Entomology, S.V. Agricultural College, ANGRAU, Tirupati – 517 502, A.P.
Five insecticides and three fungicides at recommended concentrations were evaluated as tank mix in various insecticide and fungicide combinations for their efficacy against stem borer and stem rot in rice. Among the different combinations tested no phytotoxic symptoms were observed indicating that all the combinations are safe to the rice crop. The chemical compatibility of insecticide and fungicide combinations measured through the bioefficacy studies under field conditions revealed that they insecticides, flubendiamide @ 0.1 ml/l (1.5% DH and 1.06% WE) and chlorantraniliprole @ 0.3 ml/l (1.9% DH and 1.16% WE) were highly effective against leaf folder and their combination with fungicide in no way undermined the efficacy when mixed indicating their compatibility. Similarly the fungicides hexaconazole @ 2.0ml/l (8.5%), propiconazole @ 1.0 ml/l (9.2%) were highly effective against stem rot alone and in combination with other insecticides with low per cent of disease incidence. Thus all the insecticides and fungicides used in the present investigation are compatible with each other and can be safely combined as tank mix for control of rice pests.
Pesticides, Compatibility, Phytotoxicity and Efficacy.
Rice (Oryza sativa L) is the staple food crop of Asian and developing countries feeding more than 2 billion people. India is the second largest rice producing country in the world. Rice, of late was subjected to be attacked by more than 300 species of insect pests and many diseases at various stages of crop growth (Pasalu and Katti, 2006). In Southern zone of Andhra Pradesh, leaf folder and leaf blast occur at the same stage of crop growth, therefore farmers are regularly going for combination of insecticides and fungicides, for reducing labour cost, labour shortage and economy. Keeping this in view, the present study was undertaken with certain new insecticides and most commonly used fungicides to find their efficacy against leaf folder and leaf blast as well as for testing the compatibility.
Field experiments were conducted during rabi 2012-13 and rabi 2013-14 in randomized block design (RBD) at Agricultural Research Station, Nellore. Five insecticides namely flubendiamide 480 SC @ 0.1 ml/l and chlorantraniliprole 20 SC @ 0.3 ml/l, cartap hydrochloride 50 SP @ 2.0 g/l, buprofezin 25 SC @ 2.0 ml/l and
profenophos 50 EC @ 2 ml/l and three fungicides tricyclazole 75 WP @ 0.6 g/l, hexaconazole 5 EC @ 2.0 ml/l and propiconazole 25 EC @ 1.0 ml/l were evaluated as tank mix of insecticide and fungicide combinations for their efficacy against stem borer as well as stem rot and to investigate their compatibility as tank mix application in untreated control was maintained for comparison with insecticide and fungicide sprayed plots. Popular susceptible rice variety Samba mashuri (BPT 5204) was selected for the study and grown as per the recommended package of practices.
Dead hearts (DH) and white ears (WE) of rice stem borer were recorded in 10 marked hills per plot one day before spraying and 7 Days After Spraying (DAS) in case of dead hearts. White ear counts were taken before harvesting.
The per cent of disease incidence of stem rot was recorded as per the Standard Evaluation System (SES) for Rice (IRRI, 1996). The grain yield was recorded from each net plot and calculated to kg/ha. The data was subjected to statistical analysis. Symptoms of phytotoxicity if any was also recorded at 1, 3, 5, 7 and 10 days after imposition of treatments.
During Rabi, 2012-13 the first spraying was given against stem borer at 30 DAT and the mean per cent dead hearts ranged from 25.09 to 28.17. The mean per cent dead hearts due to stem borer were lowest at 7 DAS and significantly effective treatments were flubendiamide (1.34), chlorantraniliprole (1.7), flubendiamide + tricyclazole (1.80), flubendiamide + hexaconazole (1.64), flubendiamide + propiconazole (1.82), chlorantraniliprole
+ tricyclazole (1.53), chlorantraniliprole + hexaconazole (1.20) and chlorantraniliprole + propiconazole (1.49). Next in the order of decreased efficacy were cartap hydrochloride (11.27), profenophos (11.84), cartap hydrochloride + tricyclazole (10.60), cartap hydrochloride
+ hexaconazole (10.18), cartap hydrochloride + propiconazole (10.78), profenophos + tricyclazole (12.11), profenophos + hexaconazole (10.95) and profenophos + propiconazole (10.54) that were on par. Lowest efficacy was observed in buprofezin (33.62), tricyclazole (36.70), hexaconazole (33.77), propiconazole (35.31), buprofezin
+ tricyclazole (36.28), buprofezin + hexaconazole (33.72), buprofezin + propiconazole (35.33) and untreated check (36.70) which were on par.
The white ears (WE) data prior to harvest also followed the same trend with flubendiamide and chlorantraniliprole being very effective as straight and combination treatments. Moderate efficacy was observed with cartap hydrochloride and its combination treatments which were on par. Next in the order of decreased efficacy was profenophos and its combination treatments. Buprofezin treatment recorded highest white ears incidence along with its combination treatments including straight fungicidal treatments which were on par with each other.
Thus considering the overall efficacy of the various treatments with regard to white ears, flubendiamide and chlorantraniliprole showed highest efficacy and were on par with their combination treatments (Table 1).
During Rabi 2013-14, almost similar results were obtained as that of Rabi 2012-13. The initial dead hearts (DH) per cent in various experimental plots including untreated control a day prior to spraying varied from 25.03 to 25.97 with no significant difference among various plots indicating uniform infestation of the pest. At 7 DAS the mean per cent dead hearts were least in the treatments, which were on par include flubendiamide (1.65),
chlorantraniliprole (2.17), flubendiamide + tricyclazole (1.65), flubendiamide + hexaconazole (1.43), flubendiamide + propiconazole (1.52), chlorantraniliprole
+ tricyclazole (1.62), chlorantraniliprole + hexaconazole (1.25), chlorantraniliprole + propiconazole (1.67). Next in the order of decreased efficacy were cartap hydrochloride (9.92), profenophos (10.81), cartap hydrochloride + tricyclazole (10.03), cartap hydrochloride
+ hexaconazole (10.05), cartap hydrochloride + propiconazole (10.73), profenophos + tricyclazole (10.77), profenophos + hexaconazole (10.95) and profenophos + propiconazole (10.82) that were on par. Lowest efficacy was observed in buprofezin (32.42), tricyclazole (32.34), hexaconazole (32.39), propiconazole (31.84), buprofezin + tricyclazole (31.99), buprofezin + hexaconazole (32.49), buprofezin + propiconazole (32.40) and untreated check (32.86) which were on par.
With regard to percent white ears (WE%) the most effective treatments include flubendiamide (1.06), chlorantraniliprole (1.21), flubendiamide + tricyclazole (1.39), flubendiamide + hexaconazole (0.96), flubendiamide + propiconazole (1.20), chlorantraniliprole
+ tricyclazole (1.08), chlorantraniliprole + hexaconazole (1.30), chlorantraniliprole + propiconazole (1.32) which were on par . Cartap hydrochloride with 4.03% WE was on par with cartap hydrochloride + tricyclazole (4.28) and cartap hydrochloride + hexaconazole (3.95) combinations. The least effective treatments include buprofezin (10.43), tricyclazole (10.46), hexaconazole (10.640, propiconazole (10.37), buprofezin + tricyclazole (10.57), buprofezin + hexaconazole (10.50), buprofezin + propiconazole (10.45) and untreated check (10.55). Thus it is clearly evident as in case of dead hearts flubendiamide, chlorantraniliprole and their combinations with fungicides reduced the infestation and significantly superior over the remaining treatments.
The pooled data of 2 seasons, rabi 2012-13 and 2013-14 with regard to stem borer infested tillers per cent clearly shows that the lowest dead hearts were observed in the treatments, flubendiamide, chlorantraniliprole and their combinations with fungicides, tricyclazole, hexaconazole and propiconazole. Next in the order was cartap hydrochloride, profenophos and their combinations with fungicides. The highest dead hearts per cent was observed in the treatments, buprofezin and its combinations including untreated control. With regard to the white ears per cent the same trend was observed as in the dead hearts (Fig. 1 &2 ).
Similarly Bhuvaneswari and Krishnam Raju (2013) also reiterated that chlorantraniliprole at 0.3ml/lit. in combination with hexaconazole was effective against stem borer and leaf folder.
During Rabi, 2012-13 the mean per cent of stem rot before treatmental application was ranged from 7.24 to 11.04. There was no significant difference in mean stem rot percentage among different treatments including untreated control. The mean percentage of stem rot disease after 10 days of spraying indicated that there was significant difference among the treatments. The lowest mean percentage of stem rot was observed in treatment, chlorantraniliprole + propiconazole (8.19), which was on par with the treatments, hexaconazole (8.82), propiconazole (9.83), flubendiamide + hexaconazole (8.28), flubendiamide + propiconazole (8.57), chlorantraniliprole + hexaconazole (10.61), cartap hydrochloride + hexaconazole (8.75), cartap hydrochloride + propiconazole (8.81), buprofezin + hexaconazole (9.17), buprofezin + propiconazole (9.37), profenophos + hexaconazole (8.38) and profenophos + propiconazole (8.30). The highest stem rot per cent incidence was recorded in the treatment, chlorantraniliprole (18.13) followed by chlorantraniliprole + tricyclazole (18.25) then untreated control (17.09).
Thus considering the overall efficacy among the various treatments and their combinations, hexaconazole, propiconazole and the treatments with other combinations with insecticides proved best with lowest stem rot per cent incidence. (Table 2).
During Rabi 2013-14, the mean per cent of stem rot before treatmental application was ranged from 7.9 to 10.1. There was no significant difference in mean stem rot percentage among different treatments including untreated control. The mean percentage of stem rot disease after 10 days of spraying indicated that there was significant difference among the treatments. The lowest mean percentage of stem rot was observed in treatment, hexaconazole (8.19), which was on par with the treatments, propiconazole (8.63), flubendiamide + hexaconazole (8.25), flubendiamide + propiconazole (8.88), chlorantraniliprole + hexaconazole (10.10), chlorantraniliprole + propiconazole (9.69), cartap hydrochloride + propiconazole (9.38), buprofezin + hexaconazole (10.10), buprofezin + propiconazole (9.63), profenophos + hexaconazole (8.30) and profenophos +
propiconazole (8.96). The highest stem rot percentage was observed in the treatment, profenophos + tricyclazole (17.58) which was on par with flubendiamide (16.75), chlorantraniliprole (15.78), profenophos (15.92), chlorantraniliprole + tricyclazole (17.50), cartap hydrochloride + tricyclazole (15.53), buprofezin + tricyclazole (16.85) and untreated control (16.91).
Thus considering the overall efficacy among the various treatments and their combinations, hexaconazole, propiconazole and the treatments with other combinations with insecticides proved best with lowest stem rot per cent incidence.
The pooled data on the stem rot per cent during rabi 2012-13 and 2013-14 revealed that the lowest stem rot per cent was observed in the treatments, hexaconazole, propiconazole and their combinations with insecticides except cartap hydrochloride + hexaconazole, which was next best treatment in controlling the stem rot incidence. The highest stem rot incidence per cent was observed in the treatments, chlorantraniliprole and chlorantraniliprole
+ tricyclazole including untreated control (Fig. 3).
The effectiveness of the five insecticides and three fungicides did not hindered when used in combination with each other and also no phytotoxicity symptoms were observed. All the five insecticides and three fungicides are physically and chemically compatible.