Test of Agrachemicals and Cuitmffi 17 (1 996) Ann appl &ol 128(Supplemenl)

E : R I ID T NT F BARNYARD GRASS (ECHINOCHLOA CRUSGALLI L.) IN TRA NSPLANTED RICE

Samar Singh, N K Sangwan, R K Malik and V Singh CCS Haryana Agricultural University, Regional Research Station, Uchani, Karnal- 132 00 1, Haryana, India

Kevworh: Cyhalofop butyl, anilofos, butachlor, barnyard grass, rice

w c t i o n Barnyard grass (Echinochloa crusgalli L.) is the major weed of transplanted rice in north west India. Butachlor and anilofos have been recommended for weed control in transplanted rice (2). Chlorimuron at higher doses have been found to be phytotoxic on rice (1). However, the new post emergence herbicide cyhalofop butyl may give good control of barnyard grass. The present trial evaluates the control of barnyard grass using cyhalofop butyl with the objective of using minimum herbicide dosages in transplanted rice.

Materials and Methods Two field experiments were conducted on clay loam soil having low organic matter (0.35%) and high pH (8.4) at CCS Haryana Agricultural University, Regional Research Station, Karnal, India. Thirty five days old seedlings of rice (cv. IR-64) were transplanted on July 15, 1993 by hand dibbling in plot sizes of 7 x 2 m with a distance of 20 cm between rows and 15 cm between plants. In experiment 1, treatments of cyhalofop butyl (XDE-537; 30% e.c.; Dow Elanco) at 30,60, 120 and 240 g a.i. ha-' were applied at 2 , 4 or 6 leaf stage of barnyard grass which appeared 8, 13 and 17 days after transplanting of rice, respectively, and compared with butachlor (Machete; 50% e.c.; Monsanto) at 1500 g a.i. ha-' applied pre-emergence, and a weedy and weed free check. In experiment 2, the dosages of cyhalofop butyl (as above) were applied alone or with surfactant (PG-26-2; 100% Dow Elanco) at 0.1 % at the third leaf stage of barnyard grass which appeared 10 days after transplanting of rice. These were compared with anilofos (Arozin; 2% I.C. Hoechst) at 300,400 and 500 g a.i. h-', anilofos (Aniloguard; 30% e.c.; Gharda Chemicals) at 400 g a.i. h-' and butachlor (as above) at 1500 g a.i. ha-' applied 2 days after transplanting of rice. The treatments were compared with a weedy and weed free check. Treatments in both experiments were arranged in randomised block design with three replicates. Herbicides were sprayed by using 650 litre water ha-' using a knap sack sprayer. Dry weight of weeds was recorded at 90 days after transplanting by removing the shoots of barnyard grass within a 0.5 x 0.5 m random quadrat. Shoots were sun-dried before oven drying at 70°C until constant weight was attained. Weed free plots were maintained by removing weeds after their appearance in the field throughout the crop season. Rice yield (with husk) were taken at moisture content of 12-13% as measured by Universal Moisture Meter per plot before conversion to kg ha-'.

m The dry weight of barnyard grass decreased with the increasing dosages of cyhalofop butyl regardless of application time (Table 1). The highest dosage of cyhalofop butryl of 240 g h' gave best control of weeds. However, maximum decrease in the dry weight was observed in the plots treated with butachlor at 1500 g h-'. Cyhalofop butyl at dosages of 120 g ha-' applied at the 2 or 4 weed leaf stage or its application at 240 g ha-' applied at all development stages of barnyard grass tested significantly (P = 0.05) increased the rice yield as compared to weedy check. The rice yield in cyhalofop butyl treated plots was significantly lower (P = 0.05) than in plots treated with butachlor. The dry weight of barnyard grass was significantly (P = 0.05) higher with application of cyahlofop butyl at 30,60 and 120 g ha-' than in plots treated with either butachlor at 1500 g ha-' or anilofos G at 400 and 500 g ha-' and anilofos EC at 400 g ha-' (Table 2). Application of cyhalofop butyl with a surfactant at 0.1 % concentration did not improve weed control significantly (P = 0.05) when applied at the three leaf stage although weed dry weights were progressively reduced at increasing concentration. All treatments except cyhalofop butyl at 30 g ha-' gave significantly (P = 0.05) higher rice yield when compared to the untreated plots. Weed free plots produced maximum rice yield. Chalfop butyl at 240 g ha-' had similar yields to those obtained in plots treated with butachlor at 1500 g ha-', anilofos G at 400 and 500 g ha.' and anilofos EC at 400 g ha.'.

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Table 1. Effect of cvhalofoo on drv weight of bamvar-s (e &) and v W - 1 ) of- rice aoolied at different weed erowth s-riment u

Herbicide Dosages (g a.i. ha-')

Butachlor 1500 Cyhalofop 30 Cyhalofop 60 Cyhalofop 120 Cyahlofop 240 Weedycheck - Weed free - SED (d.f.=28)

Weed erowth stage Pre-emereencp T wo leaf Four leaf six leaf Drywt. Rice Drywt. Rice Drywt.Rice Drywt. Rice weeds. yield weeds yield weeds yield weeds yield 190.3 4964 -

- 470.5 2702 533.9 2630 584.2 2559 - 430.5 2773 484.1 2761 518.3 2654 - 301.7 3559 387.3 3352 505.9 2690 - 267.5 3678 300.2 3446 345.5 3178

748.9 2115 0 5649

Dry wt. weeds = 50.4 Rice yield = 347

Table 2. Effect of cvhalofop with or with0 ut surfactant and other herbicides applied at d i w weed mowth stages on drv weight of bamvard m s (u m-*) and vi- ha') -Dlm ted rice (Experiment 2)

Herbicide Dosages Weed glowth stave (g a.i. ha-') Pre-emereens leaf

WlthoutsurfactantWlthsurfactant Drywt. Rice Drywt. Rice Drywt. Rice weeds yield weeds yield weeds yield

Anilofos EC 400 38.2 4988 Anilofos G Anilofos G Anilofos G Butachlor Cyhalofop Cyhalofop Cyhalofop Cyhalofop Weedy check Weed free SED (d.f. = 28)

300 400 500

1500 30 60

120 240

142.6 4042 33.2 5214 27.8 5488 12.6 5523

571.8 3031 0 5890

Dry wt. weeds = 36.2

342.3 249.3 186.2 85.0

3547 302.1 3916 184.8 4511 142.6 5333 43.8

Rice vield = 402

3654 4322 4892 5516

Discussion Cvhalofoo bum1 did not have any advantage over the herbicides already used to control barnyard grass. . - The activity of cyahlofop butyl was improved by adding surfactant but high concentrations of surfactant may be required to further improve the efficiency of this herbicide. Application early post emergence is likely to be more successful than late post emergence treatment.

References 1. Singh Samar, Malik R K, Dhawan R & Singh, S. 1992. Annual Weed Science Conference, March

'92, Him, Abstract 9.4. 156. 2. Thomas CG & Sreedevi P. 1993. Proceedings International Symposium, Indian Society of Weed

Science, Nov. '93, Hisar, 3,46-47.