Weed spectrum and shifts in cotton associated weeds in Punjab

Survey of weed flora of cotton fields was conducted from 1985 to 1990 and 1992 to 1997 and thereafter weed surveillance during 2001,2002 and 2006 in the State of Punjab to know the weed flora composition and its shift with time in cotton fields. The data revealed that 65 weed species were found infesting cotton fields. The predominant weeds were Eleusine aegyptiacum (L.) Desf. (madana), Trianthema portulacustrum L. (it-sit), Digera arvensis Forsk. (tandla), Cyperus rotundus L. (motha/della), Digitaria ciliaris (Retz.) Koel (takri-ghas), and Echinochloa colonum (L.) Link, (swanki). Besides these Eragrostis tenella (L.) P. Beauv. (love-grass), Sorghum halepense (L.) Pers. (baru), Physalis minima L. (mamola), Phyllanthus niruri L. (hazardani), Celosia argentea L. (salara) and Corchorus tridens L. (jangli-jute) were also important weeds of this crop. The weed survey/surveillance showed that some weeds namely Cenchrus cathartichus L. (kutta-ghas) and Tribulus terrestris L. (bhakra) disappeared or are on the verge of disappearance and density of some weeds like Eragrostis tenella (L.) P. Beauv., Sorghum halepense (L.) Pers., Physalis minima L., Phylanthus niruri L., Celesoia argentia L. and Corchorus tridense L. reduced considerably during these years may be due to improved agronomic practices. On the other hand density of E. colonum (L.) Link, Convolvulus arvensis L. (hiran-khuri) and Ipomoea pestigridis L. (makru) were on the increase. Some new weed species like Eragrostis diarrhena L. (japani-ghas), Cyperus compresus L. (chota-della) etc were found infesting cotton fields.