Introduction to major field crops (1+1)

Weed Management

Soybean, being a rainy season crop, is heavily infested with many grassy as well as broad leaf weeds. The most common weeds infesting the soybean crop areDactylocteniumaegyptium, eleusineindica, Sorghum halepense, CyperusrotandusandCynodondactylonamonggrassy weeds and Celosia argentia, Digitaria sp., Trienthemapartulactrum,TribulusterristrisandPhyllanthusniruri among broad leaf weeds.

Crop is sensitive to weed competition, particularly in early growth phases.The most critical period for crop weed interference is initial 30-45 days. Weeds emerging after this period are suppressed by smothering action of crop.Yield loss in soybean may range from 25-70 per cent depending upon intensity and infestation of weeds. Besides yield loss, quality is also adversely affected.

Weeds in soybean can be controlled by using khurpi or handhoe. Generally two weedings, one at 20-25 days after sowing and other at 35-40 days after sowing keeps most of the weeds under control. Timely availability of labour and time consuming are main difficulties of hand weeding.

Fig: Intercultural operation.

Herbicidal weed control has been found efficient and economical in soybean. Pre-plant application of Fluchloralin or Trifluralin @ 0.5-1.0 kg/ha or pre-emergence application of Alachlor (1.0-2.0 kg/ha) or Butachlor (2.0 kg/ha) or Metolachlor (1.5-2.0 kg/ha) orPendimethalin (1.0 kg/ha) orOxadiazon (0.5-1.0 kg/ha) and post-emergence application of Sethoxydim (0.25-0.50 kg/ha) or Fluazitop-p (0.15-0.25 kg/ha) found to be effective in controlling weeds.