Weed Management in Rice

Weed Management in Nursery

• Apply any one of the pre-emergence herbicides viz., Pretilachlor + safener 0.3kg/ha, on 3rd or 4th day after sowing to control weeds in the low land nursery.
• Keep a thin film of water and allow it to disappear.
• Avoid drainage of water. This will control germinating weeds.
• Butachlor 2.0 l/ha (or) Pendimethalin 2.5 l/ha (or) Anilophos 1.25l/ha.
• Herbicides should be applied on 8 DAS with thin layer of water in the field.

Main field Weed Management

• Use of rotary weeder from 15 DAT at 10 days interval. It saves labour for weeding, aerates the soil and root zone, prolongs the root activity, and improves the grain filling though efficient translocation and ultimately the grain yield.
• Cultural practices like dual cropping of rice-azolla, and rice-green manure (described in wet seeded rice section 2.5 & 2.6 of this chapter) reduces the weed infestation to a greater extent.
• Summer ploughing and cultivation of irrigated dry crops during post-rainy periods reduces the weed infestation.

Pre-emergence herbicides

• Use Butachlor 1.25kg/ha or Anilophos 0.4kg/ha as pre-emergence application. Alternatively, pre-emergence application of herbicide mixture viz., Butachlor 0.6kg + 2,4 DEE 0.75kg/ha, or Anilophos + 2, 4 DEE ‘ready-mix’ at 0.4kg/ha followed by one hand weeding on 30 - 35 DAT will have a broad spectrum of weed control.
• Any herbicide has to be mixed with 50kg of dry sand on the day of application (3 - 4 DAT) and applied uniformly to the field with thin film water on the 3rd DAT. Water should not be drained for next 2 days from the field (or) fresh irrigation should not be given.
• Pre- emergence application of pretilachor at 1.0 kg a.i. ha-1 on 3 DAT + weeding with Twin row rotary weeder at 40DAT
• PE Pyrazosulfuron ethyl 10 % WP @ 150 g ha-1 on 3 DAT + hand weeding (HW) on 45 DAT. PE butachlor 0.75 kg a.i. ha-1 + bensulfuron methyl 50 g ha-1 on 3 DAT + HW on 45DAT
• PE Oxadiazon 87.5 g a.i. ha-1 followed by Post emergence (POE) 2,4-D 1 kg a.i. ha-1 along with hand weeding on 35DAT.
• PE butachlor 0.75 kg per hectare + bensulfuron methyl 50 g ha-1 on 3 DAT followed by mechanical weeding on 45 DAT is effective for broad spectrum weed control.
• Crop growth and yield were enhanced by butachlor 1.2 + 2,4-DEE 1.5 lit ha-1 with 100% inorganic nitrogen.
• Conventional tillage of one dry ploughing and two passes of cage wheel puddling combined with pre-emergence application of butachlor at 1.25 kg ha-1 under lowland situation.
• Stale bed preparation by pre-puddling minimum tillage with glyphosate combine with post-plant pre emergence butachlor 1.25 kg ha-1 resulted in increased rice grain yield, net income and B: C ratio in rice-rice cropping.

Post - emergence herbicides

• If pre-emergence herbicide application is not done, hand weeding has to be done on 15th DAT.
• 2,4-D sodium salt (Fernoxone 80% WP) 1.25 kg/ha dissolved in 625 litres with a high volume sprayer, three weeks after transplanting or when the weeds are in 3 - 4 leaf stage.
• Early post emergence application of Bispyripac sodium 50 g a.i. ha-1 (2-3 leaf stage of weeds) + Hand weeding on 45DAT

Dry Seeded Irrigated Un-Puddled Lowland Rice Weed management:

• First weeding should be done between 15 and 21 days aftergermination.
• Second weeding may be done 30 - 45 days after firstweeding.
• Apply pendimethalin 1.0kg/ha on 5 days after sowing or Pretilachlor + safener (Sofit) 0.45kg/ha on the day of receipt of soaking rain followed by one hand weeding on 30 to 35 days after sowing.

Dry Seeded Rainfed Un-Puddled Lowland Rice Weed management:

• First weeding can be done between 15 and 21 days after germination.
• Second weeding may be done 30 - 45 days after first weeding.
• Apply pendimethalin 1.0kg/ha on 5 days after sowing or Pretilachlor + safener (Sofit) 0.45kg/ha on the day of receipt of soaking rain followed by one hand weeding on 30 to 35 days after sowing.
• Seed drill sowing with pre-emergence application of pretilachlor + safener @ 0.3 kg/ha followed by two weedings with star / rotary weeder is recommended.

Dry seeded Rainfed Un-puddled Lowland Rice with Supplemental Irrigation Weed management:

• First weeding should be done between 15 and 21 days after germination.
• Second weeding may be done 30 - 45 days after first weeding.

Author- 

Dr. Rajendra Kumar, SKRAU, Bikaner
Dr. Vinod Kumar, MPUAT, Udaipur
Ms. Yamini Tak, Asst. Prof. AU, Kota