0 Views
K. PULLAM RAJU*, P. RAJASEKHAR, C.P.D. RAJAN AND N.C. VENKATESWARLU
Department of Entomology, S.V. Agricultural College, Tirupati
Five insecticides and three fungicides at recommended concentrations were evaluated as tank mix in various insecticide and fungicide combinations for their efficacy against leaf folder and leaf blast 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 the insecticides, flubendiamide @ 0.1 mL L-1 (5.79%) and chlorantraniliprole @ 0.3 mL L-1 (5.8%) were highly effective against leaf folder and their combination with fungicide in no way undermined the efficacy when mixed indicating their compatibility. Similarly the fungicide tricyclazole @ 0.6 g l-1 was highly effective against leaf blast alone and in combination with other insecticides with per cent disease index of 11.0. 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.
Rice (Oryza sativa L) 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 attack 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 as a measure of economy. Keeping this in view, the present study was undertaken with certain new insecticides and most commonly used fungicides to find their efficacy on leaf folder and leaf blast as well as for testing the compatibility.
The 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-1 and chlorantraniliprole 20 SC @ 0.3 mL L-1, cartap hydrochloride 50 SP @ 2.0 g l-1, buprofezin 25 SC @ 2.0 mL L-1 and profenophos 50 EC @ 2.0 mL L-1 and three
fungicides tricyclazole 75 WP @ 0.6 g l-1, hexaconazole 5 EC @ 2.0 mL L-1 and propiconazole 25 EC @ 1.0 mL L-1 were evaluated as tank mix of insecticide and fungicide combinations for their efficacy against leaf folder as well as leaf blast and to investigate their compatibility as tank mix application. An untreated control was maintained for comparison sake. Popular susceptible rice variety Samba mashuri (BPT 5204) was selected for the study and grown as per the recommended package of practices.
Population counts of rice leaf folder or webbed leaves were recorded in 10 marked hills per plot one day before spraying and 7 Days After Spraying (DAS).
The Per cent Disease Index (PDI) of leaf blast 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-1. 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 leaf folder at 60 DAT and the mean population of leaf folder by way of leaf folder damage ranged from 31.66% to 33.16%. The mean per cent infested leaves
due to leaf folder were lowest at 7 DAS and significantly effective treatments were flubendiamide (1.01), chlorantraniliprole (1.01), flubendiamide + tricyclazole (1.02), flubendiamide + hexaconazole (1.01), flubendiamide + propiconazole (1.09), chlorantraniliprole +tricyclazole (1.04), chlorantraniliprole + hexaconazole (0.99) and chlorantraniliprole + propiconazole (1.0) which were followed by cartap hydrochloride (9.45), cartap hydrochloride + tricyclazole (11.36), cartap hydrochloride + hexaconazole (10.99), cartap hydrochloride + propiconazole (11.33) which were on par . The lowest per cent infested leaves were in untreated check (37.63), buprofezin (39.70), tricyclazole (37.30), propiconazole (37.73), buprofezin + tricyclazole (37.48), buprofezin + hexaconazole (37.57), buprofezin + propiconazole (38.39) which were on par.
The overall efficacy of insecticide and fungicide combinations indicated that the insecticides flubendiamide, chlorantraniliprole are highly compatible with all fungicides by recording lowest per cent infested leaves. These insecticides were followed by cartap hydrochloride and its combinations with fungicides (Table 1).
During Rabi 2013 -14, almost similar results were obtained as that of Rabi 2012-13. At 7 DAS the mean per cent infested leaves were least in the treatments, flubendiamide (1.03), chlorantraniliprole (1.09), flubendiamide + tricyclazole (1.18), flubendiamide + hexaconazole (0.98), flubendiamide + propiconazole (1.05), chlorantraniliprole + tricyclazole (1.01), chlorantraniliprole
+ hexaconazole (1.09), chlorantraniliprole + propiconazole (0.91) which were on par. These treatments were closely followed by cartap hydrochloride (11.42), cartap hydrochloride + tricyclazole (11.10), cartap hydrochloride
+ hexaconazole (10.07), cartap hydrochloride + propiconazole (10.14). The highest per cent infested leaves was observed in buprofezin (39.15), tricyclazole (39.43), hexaconazole (38.84), propiconazole (39.23), buprofezin
+ hexaconazole (40.20), buprofezin + propiconazole (40.19) and untreated check (38.32).
The pooled data of two seasons clearly brought out flubendiamide and chlorantraniliprole and their combinations with tricyclazole, propiconazole, hexaconazole, recorded significantly low leaf folder infested leaves. Prajapathi et.al., (2005) also reported that the damage caused by insect pests specifically leaf folder was significantly lower following application of cartap hydrochloride alone as well as in combination with
fungicides hexaconazole and propiconazole compared to untreated control. The present study results also corroborate the findings of Prajapathi et.al., (2005) wherein cartap hydrochloride was found effective both as individual treatment and combination treatments with fungicides. Similarly Bhuvaneswari and Krishnam Raju (2013) also reported that chlorantraniliprole @ 0.3 mL L-1 in combination with hexaconazole was effective against stem borer and leaf folder in paddy.
With regard to the leaf blast the mean per cent disease index before treatmental application ranged from 9.2-11.0. The mean PDI of leaf blast after 10 DAS during rabi, 2012-13 indicated that there were significant differences among the treatments. The lowest PDI of 11.0 in case of leaf blast was observed in the treatments tricyclazole, flubendiamide + tricyclazole, chlorantraniliprole + tricyclazole, buprofezin + tricyclazole and profenophos + tricyclazole. Similarly during rabi 2013-14, the results followed the same trend with tricyclazole alone and their combinations proving best with lowest PDI. Even the pooled data of the two seasons clearly revealed that the treatments tricyclazole alone and tricyclazole with other insecticidal combinations were with lowest incidence of leaf blast. All the treatments which effectively control pest and disease have recorded significantly higher grain yield as compared to the check (Table 2).
The effectiveness of the five insecticides and three fungicides did not in any way was hindered.