Kharif crops are infested with diverse types of weed flora which includes grass, broad leaf and sedge weeds. The intensity and diversity of weeds are also higher in the kharif season as compared to the rabi season in the crops. Infestation of weeds is more because of frequent irrigations applied to crops and later due to rainfall in the monsoon period.
Weeds have more potential for growth and development as compared to crop plants even in adverse climatic conditions. If the weeds emerge with the crop during the initial stages of growth, then weeds compete more with crops for resources and are difficult to control in later stages resulting in higher yield losses.
Therefore, it is highly recommended that weeds should be controlled in the critical weed competition period of the crop. In addition to that for getting good results farmers are advised to follow integrated weed management approaches for effective and economical control of weeds. In this article, different cultural, mechanical, and chemical methods are discussed for effective control of weeds in major kharif crops. Rice is a major Kharif crop in Punjab. It is infested with different types of grass, broad leaf, and sedge weeds.
Weed Control in Puddled Transplanted Rice: In transplanted rice, weeds can be controlled by doing hand weeding 15 and 30 days after transplanting. For effective control of swank and moderate control of other weeds, apply one of the pre-emergence herbicides like machete/markchlor/ thunder/ punch 50 EC (butachlor) or Fast-mix 50 EW (butachlor) at 1200ml/acre or Rifit/Markpretila/MifPretila 50 EC (pretilachlor) at 600 ml/acre or Rifit Plus 37 EW (pretilachlor) at 750 ml/acre mix with 60 kg sand/acre in standing water within 2- 3 days of transplanting. Spray Arozin/Anilogaurd/Padigard 30 EC (anilofos) at 500ml/acre 2-3 days of transplanting in standing water for control of kanki weed.
Pre-emergence application of Sathi 10 WP (pyrazosulfuron ethyl) at 60g/acre in standing water provided effective control of paddy mothas and broad-leaf weeds. If pre-emergence herbicide application has been skipped due to some reason or ponding of water is a problem due to power cuts or further transplanting in the process then apply 40 ml/acre Granite 240 SC (penoxsulam) at 10-12 days of transplanting in 150 litres of water for the control of swank, paddy mothas and broadleaf weeds.
Granite should be applied when there is no standing water in the field and irrigate the field one day after herbicide application for better control of weeds. For effective control of paddy mothas and swank, at 20-25 days of transplanting, spray Nominee Gold/Wash out/Macho/ Taarak 10 SC (bispyribac) 100 ml/acre in 150 litres of water in rice. Fields infested with Leptochloa (chini) gha and kanki, apply Ricestar 6.7 EC (fenoxaprop) 400 ml/acre at 20-25 days of transplanting in 150 litres of water.
For control of paddy mothas and broadleaf weeds including ghrilla, sanni, Ammannia etc., spray 30 g Algrip 20 WG (metsulfuron) or 50 g Sunrice15 WG (ethoxysulfuron) or 8 g per acre Almix 20 WP (metsulfuron methyl +chlorimuron ethyl) per acre in 150 litres of water at 20 days of transplanting when the weeds are at 2-4 leaf stage. For the control of swank, paddy mothas and broad leaf weeds in transplanted rice, apply Novixid 3.25 OD (florpyrauxifen-benzyl 1.31%+ penoxsulam 1.2%) at 500 ml/acre or Eketsu 43 WG (bispyribac sodium 38%+ chlorimuron ethyl 2.5% + metsulfuron methyl 2.5%) at 40g/acre using 150 litres of water at 2-4 leaf stage of weeds about 20-25 days after transplanting.
Weed Control in Direct-seeded Rice: The intensity and diversity of weeds in direct-seeded rice are higher than in transplanted rice. Even though, different herbicides are recommended according to weed flora present in the field and give effective control of weeds in direct-seeded rice.
Prefer direct sowing of rice in tar wattar condition and later apply first irrigation around 21 days after sowing which reduces weed emergence with the initial phases of crop growth. In tar-wattar rice, for the control of annual grass weeds and some broadleaf weeds spray 1.0 litre per acre Stomp/Bunker 30 EC (pendimethalin) in 200 litres of water immediately after the sowing of rice in good soil moisture. The rice seeding can be done with Lucky Seed Drill, in which sowing and herbicide spray are done simultaneously.
In the case of direct seeding of rice in dry fields, irrigation is applied immediately after sowing, and herbicide is sprayed when the fields come to wattar condition which in general is within 1 to 2 days of sowing. Post-emergence herbicide can be applied 20-25 days after sowing depending upon the type of weed flora present in the field. Nominee Gold 10 SC (bispyribac sodium) 100 ml per acre effective for swank and paddy mothas; Ricestar 6.7 EC (fenoxaprop-p-ethyl) 400 ml per acre effective against Madhana, chini gha, chiri gha, takri gha.
Nominee gold 10 SC (bispyribac sodium) can be applied 15-25 days after sowing. Post-emergence application of Almix 20 WP (chlorimuron ethyl 10% + metsulfuron methyl 10%) at 8 g per acre effective for broadleaf weeds, paddy mothas and gandi wala motha. For control of Swank, paddy mothas, gandi wala motha and broadleaf weeds apply Eketsu 43 WG (bispyribac sodium 38%+ chlorimuron ethyl 2.5% + metsulfuron methyl 2.5%) at 40 g/acre using 150 litres of water. Post-emergence herbicides should be applied at the 2-4 leaf stage of weeds in the moist field and afterwards, maintain proper soil moisture in the field for a week to get better weed control.
Weed Control in Cotton: Cotton being a wider row spacing crop, weeds establish well in-between spaces and if not controlled at an early stage compete with nutrient resources at the flowering and fruiting stage which results in nutrition imbalance Hoeing twice or thrice is effective in cotton for weed control. The first hoeing should be done before the first irrigation when weeds are small.
For weeding tractor tractor-mounted cultivator/tractor-operated rotary weeder/triphali or wheel hand hoe can be used before fruiting in cotton. For chemical weed control, apply Stomp 30 EC (pendimethalin) the same day after sowing as pre-emergence using 200 litres of water for the control of itsit, madhana, makra weeds.
Stomp provided good results if applied in moist soil preferably in the morning and evening hours. In some fields weeds emerge after first irrigation or after rainfall, Stomp 30 EC can also be applied as post-emergence after first irrigation when the field comes at wattar condition. Already emerged weeds can be uprooted with light hoeing/interculture operation.
For the control of annual grass and broad leaf weeds, spray Hitweed Maxx 10 MEC (pyrithiobac sodium 6%+quizalofop ethyl 4%) at 500 ml/acre using 150 litres of water after first irrigation, in moist soil, at 2-5 leaf stage of weeds. Alternatively, at 6-8 weeks after sowing (crop height 40-45 cm), directed spray of Gramoxone 24 SL (paraquat) at 500 ml per acre or Sweep Power 13.5 SL (glufosinate ammonium) at 900 ml/acre in 100 litres of water using protective hood to control weeds in between the crop plants. Paraquat and glufosinate are non-selective herbicides and can cause injury to the crop if these fall on the crop leaves.
Weed Control in Maize: Wider row-to-row spacing and slow growth in initial days allow the weeds to flourish in maize and lead to higher yield reduction if not managed during early stages. Give two hoeings about 15 to 30 days after sowing with khurpa/kasaula/wheel-hoe/triphali/tractor-drawn cultivator.
Alternatively, uniform spreading of 30 quintal per acre of paddy straw mulch at the time of sowing provides effective control of annual weeds or intercropping of fodder cowpea (one or two rows) in between maize rows and harvest it at 35 to 45 days after sowing as fodder, thereafter no weed control operation is required. For chemical weed control, spray Atrataf/Atragold/Masstaf/Atari/Traxx 50 WP (atrazine) at 800 g/acre in medium to heavy textured soils and 500 g/acre in light soils within ten days of sowing, using 200 litres of water or spray atrazine at 250 g/acre on the crop rows in bands (20 cm) followed by hoeing/inter-culture in between the crop rows at 15 to 30 days after sowing.
This herbicide is effective against annual grasses and broad-leaf weeds especially itsit. Alternatively, for the control of complex weed flora spray Laudis 420 SC (tembotrione) at 105 ml/acre in 150 litres of water at 20 days after sowing. For the control of dila/motha, apply 2,4-D amine salt 58 SL at 400 ml/acre in 150 litres of water 20-25 days after sowing.
Weed Control in Kharif Pulses: Pulses are more prone to yield loss if the weeds are not controlled well in time. For weed control in moong and mash, go for one hoeing at 4 weeks after sowing and if the need arises second hoeing can be done at about 2 weeks thereafter. Similarly, in Arhar and Soybean, hoeing twice at 3 and 6 weeks after sowing provides control for the weeds. Alternatively, for chemical control of weeds in Arhar, spray Stomp 30 EC (pendimethalin) at 1.0 litre/acre within 1-2 days of sowing using 200 litres of water or use Stomp 30 EC at 600 ml/acre after sowing and one hand hoeing 6 weeks after sowing. In Soybean, spray Stomp 30 EC 600 ml/acre within 1-2 days of sowing using 200 litres of water per acre and if the need arises, spray Parimaze 10 SL (imazethapyr) at 300 ml/acre at 15-20 days after sowing using 150 litres of water per acre.
Finally, weeds emerging at a later stage of crops should be uprooted before the seed is set to reduce the seed bank in the soil.