Department of Agronomy
1Contribution from Department of Agronomy, C.R.R.I., Cuttack-6.
To test the efficacy of some pre and post emergence herbicides for controlling weeds in upland rainfed direct sown rice, field trials were conducted at C. R. R. I., Cuttack during the years 1978 and 1979 in kharif season. A total of thirteen herbicides (seven herbicides common in both the years) were used in these experiments. The results of the experiment conducted during"1978, which was an year of good crop growth and low weed-incidence, the herbicides avirosan (S-2-methyl-piperidinocarbonyl methyl 00-dipropyl phos-phorodithioate + 2-(l, 2-dimethyl-amino-4 hydroxy-6 methyl pyrimidine) and penoxalin (N-(l-ethyl propyl) 3,4-dimethyl-2,6-dinitro-benzenamine) were at par with hand weeded (twice) check in grain yield. In the subsequent year, 1979, which was marked by heavy weed incidence and low yields only herbicides such as butachlor (N-butoxymethyl-a-chloro-2, 6-diethylacetani-lide), avirosan, dinitramine (N ‘N’-diethyl-2, 6-dinitro-4-trifluoro-methyl-m-phenylenediarnine) and nitrofen (2, 4-dichloro-4’ -nitrodiphenyl ether) treatments gave comparable yields with hand weededj plots. Majority of pre-emergence herbicides showed phytotoxicity on crop due to rainfall-herbicide interaction. Highest phytotoxicity was shown by oxadiazon (5-/e/7-buty]-3 (2, 4-dichloro-.’i-isoproxy phenyl)-!, 3, 4-oxadiazol-2-one) at the dosage tried i.e. 1 kg a.i./ha.
