Special Weeds in Cropped Areas – Striga
Striga or Witch Weed (Striga lutea):
There species are Striga lutea, S. astatica, S. hirsute. They are all annual parasitic weeds propagated from abundant seeds. Grows in light soil in crops like jowar, bajra, sugarcane, rape seed and mustard. After germination, produces 2-3 long radical farm Haustoria on nearly host roots and continue their growth. They suck water, nutrient and food material from them. Each striga produces a million seeds after 30 days of its emergence. It grows under soil for 20 days and then it emerges out as green plant. At this stage it is a partial parasite.
Trap cropping is a conventional practice of controlling striga. Trap crop induce striga seeds to germinate but striga fail to make haustori on them and perished. Cotton, sunflower, soybean are effective trap crops for striga. Dicamba kills striga effectively than 2.4-D. Repeated application are required in maize. Fenac (1-3 kg/ha) as pre-planting control the striga in maize and sugarcane. Trifluralin and nitraline are used to control striga weed in cotton and soybean.