Vol. 17 No. 1
Bioefficacy of pretilachlor and pyrizosulfuron-ethyl in delaying critical time of competition for Echinochloa crus-galli in direct seeded rice
Author(s): S. TAHIR, S. IQBAL, M. NAZIR, M. A. BHAT, F. BAHAR AND B. JAN
Abstract: Echinochloa crus-galli is one of the most problematic weeds of rice in Kashmir Valley. In a two-year study to evaluate the application time and efficacy of variable doses of pretilachlor and pyrizosulfuron-ethyl at 3 to 6 days after sowing in direct seeded rice to mitigate and reduce the longevity and emergence of Echinochloa crus-galli using of five herbicide treatments along with two checks (weedy and weed free), a delayed emergence of 45 days was observed in Echinochloa crus-galli when highest dosage of pre-mixed pretilachlor + pyrazosulfuron-ethyl 600 g/ha was applied at sixth day after sowing which was however, statistically at par with pretilachlor + pyrazosulfuronethyl 750 g ha-1 for 54 days.Individual application of pretilachlor and pyrazosulfuron-ethyl slightly differ in reducing early emergence of Echinochloa crus-galli with an efficacy upto 33 and 29 days, respectively. Critical period was determined as 8-54 days after seeding under different weed control practices during both the years based on conversion of temperature into growing degree days. Visible estimates of rice yield were lowest (54.29 q ha-1) in weedy check and highest in weed free (89.68 q ha-1) followed by pretilachlor and pyrizosulfuron-ethyl 750 g ha-1 (88.77 q ha-1).
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