Weed management in spring-planted sugarcane (Saccharum officinarum)-based intercropping systems

Field studies were conducted during spring seasons of 2000–01, 2001–02 and 2002–03 on a sandy loam soil to evaluate relative profitability of intercropping spring-planted sugarcane (Saccharum officinarum L.) with greengram [Phaseolus radiatus (L.) Wilczek], blackgram [Phaseolus mungo (L.) Hepper] and okra (Abelmoschus esculentus L.) in 1:1 ratio as compared to its sole cultivation and to assess the efficacy in these intercropping systems. Four weed-control treatments, viz. unweeded control, two hand-hoeings (30 days after sowing and after harvest of intercrops), pendimethalin @ 0.75 kg/ha as pre-emergence and trifluralin @ 1.0 kg/ha as pre-plant to intercrops. These were tested in randomized block design (RBD) with three replications. The data of 3 years showed that intercropping of okra reduced the cane yield by 8.1% compared with sole sugarcane. However, this intercropping system recorded the highest mean cane-equivalent yield (74.2 tonnes/ha) as well as net returns (Rs 37,461/ha) among the cropping systems. The net returns under sole sugarcane were Rs 24,950/ha. Uncontrolled growth of weeds reduced the yield of sole sugarcane by 26.7%. One pre-emergence application of pendimethalin @ 0.75 kg/ha or pre-plant incorporation of trifluralin @ 1.0 kg/ha recorded effective control of annual weeds and gave cane yield, intercrop yield and net returns comparable to two handhoeings. These herbicides, however, did not show their herbicidal effect on Cyperus rotundus.