Weed management in crops and cropping systems

WS 3.1.1 Herbicide combinations for control of complex weed flora in transplanted rice

Cooperating centres: Hisar, Ludhiana, Bhubaneswar, Faizabad, Pantnagar, Bengaluru, Coimbatore, Thrissur, Pusa and Karaikal

CCSHAU, Hisar

Weed flora of the field was dominated by Echinochloa crus-galli along with broadleaf weed Ammannia baccifera and sedges like Cyperus difformis. All the herbicidal treatments except pyrazosulfuron fb chlorimuron+metsulfuron (RM) provided effective control of grassy weed Echinochloa crus-galli in transplanted rice. Addition of ethoxysulfuron and chlorimuron+metsulfuron as tank-mix with bispyribac and in sequence with pretilachlor improved control of broadleaf weeds and sedges. Similarly, ready-mix treatments of pretilachlor + pyrazosulfuron 615 g/ha and triafamone + ethoxysulfuron 60 g/ha also provided effective control of grassy as well as broadleaf weeds and sedges. There was no phyto-toxicity of different herbicidal treatments on the crop.

All the herbicidal treatments except pyrazosulfuron fb chlorimuron+ metsulfuron (RM) produced effective tillers, grain yields and higher B: C ratio similar to weed free check.

PAU, Ludhiana

Pre-mix of triafamone+ethoxysulfuron, pretilachlor, pyrazosulfuron recorded poor control of I. rugosum. Tank-mix of bispyribac with ethoxysulfuron, and its sequential applications with pendimethalin or pre-mix of chlorimuron+ metsulfuron recorded complete control of all weeds (100% WCE) and recorded lowest depletion of N, P and K by weeds at harvest. Tank-mix of bispyribac with ethoxysulfuron and its sequential applications with pendimethalin or pre-mix of chlorimuron+ metsulfuron recorded the highest B: C ratio. The rice grain yield reduction in weedy check varied from 38 to 50%. All herbicides were safe to rice crop.

This study indicated that post-emergence application of tank-mix of bispyribac with ethoxysulfuron, and its sequential applications with pendimethalin or pre-mix of chlorimuron+ metsulfuron are best ways for controlling complex weed flora and enhancing productivity and profitability from transplanted rice.

OUAT, Bhubaneswar

The floristic composition of the experimental site was dominated with grasses like Digitaria ciliaris, Cynodon dactylon, Echinochloa colona and broadleaf weeds like Ageratum conyzoides, Cleome viscosa, Ludwigia parviflora, Physalis minima, Chrozophora rottleri. Dominant sedge was Cyperus rotundus. Preemergence application of pendimethalin followed by bispyribac-Na recorded significantly least weed density at all stages of observation. Weed free treatment recorded significantly lowest biomass of 1.8, 2.1 and 2.3 g/m2 at 30, 60 DAT and at harvest, respectively. At 30 DAT, application of pendimethalin + bispyribac recorded significantly lower biomass of 1.6 g/m2 which was at par with triafamone + ethoxysulfuron (1.7 g/m2) at later stages, also bispyribac + Almix treated plots exhibited lower values of biomass.

Application of pendimethalin+bispyribac recorded significantly higher grain yield of 4.8 t/ha and B:C ratio of 2.8 which was superior to application of triafamone + ethoxysulfuron (4.5 t/ha) and (2.7). Weed free plots recorded rice yield of 4.9 t/ha where as weedy treatment recorded the lowest yield(1.6 t/ha). Highest net return of 21,478/ha was obtained from post emergence application of pendimethalin+ bispyribac followed by triafamone+ ethoxysulfuron (20,713/ha).

NDUAT, Faizabad

Dominant weeds were Echinochloa colona and E. crus-galli among the grassy, Eclipta alba, Caesulia axillaris and Ammannia baccifera among broadleaved and Cyperus spp. and Fimbristylis spp. among sedges were recorded. Bispyribac-Na provided control of almost all type of the weeds but it was very effective against Echinochloa colonaand E. crus-galli. Pretilachlor at 750 g /ha applied at 0-3 DAT fb Almix also controlled grassy weeds very effectively but C. axillaris was controlled moderately. Tank mixing of Almix at 4 g/ha with bispyribac-Na further improved control of grassy and non-grassy weeds significantly over single application. However, among weed control measures, maximum WCE (%) was recorded with the combination of triafamone + ethoxysulfuron (RM) (88.2%). No herbicide combination caused the phyto-toxocity on the rice crop.

Maximum grain (5.80 t/ha) and straw (6.96 t/ha) yield were recorded with triafamone + ethoxysulfuron (RM) application which was at par with penoxsulam + cyhalofop (135 g/ha at 15-20 DAT), bispyribac + chlorimuron + metsulfuron (20+4 g/ha at 25 DAT 3-4 leaf stage). Triafamone + ethoxysulfuron (RM) treatment recorded maximum net return (57,646) and BCR (2.3) than other weed control measures

GBPUAT, Pantnagar

Experimental area was infested with E. colona (17.3%), E. crus-galli (28.8%), L. chinensis (11.5%) among the grasses, C. axillaris (15.4%), A. baccifera (11.5%) among broadleaved, C. difformis (9.7%) and F. miliacea (5.8%) among the sedges at 60 DAT.

Minimum population of grassy weeds was obtained with the combination of bispyribac-Na (25 g/ha)+ ethoxysulfuron (18.75 g/ha) applied as postemergence and ready mix of penoxsulam+ cyhalofopbutyl (135 g/ha) which was at par with sequential application of pendimethalin at 1000 g/ha (pre) fb bispyribac-Na at 25 g/ha (post). Among the herbicidal application, the lowest dry matter accumulation (2.5 g/m2) and highest weed control efficiency (98.8%) was obtained with the ready mix application of penoxsulam+ cyhalofop- butyl followed by pendimethalin 1000 g/ha as pre-emergence fb postemergence application of bispyribac-Na 25 g/ha.

Twice hand weeding (25 and 45 DAT) recorded 57.1% increase in grain yield over the weedy check, whereas, maximum increase (69%) in grain yield was recorded with the application of penoxsulam+cyhalofop-butyl (135 g/ha) and pendimethalin (1000 g/ha) fb bispyribac-Na (25 g/ha) over the weedy check. Ready mix application of penoxsulam+cyhalofop-butyl (135 g/ha) and pendimethalin (1000 g/ha) fb bispyribac-Na (25 g/ha) recorded the highest grain yield (7.1 t/ha) which was at par with alone application of penoxsulam at 22.5 g/ha (6.7 t/ha) and combination of bispyribac–Na+ ethoxysulfuron (6.8 t/ha) applied as post emergence

UAS, Bengaluru

In summer, 2015, major weed flora was, Scirpus sp., Fimbristylis miliacea (among sedges), Panicum triferon, Paspalum distichum, (among grasses), Spilanthes acmella, Rotala verticillaris, Marselia quadrifolia, Ludwigia parviflora, Gnaphalium polycoulon (among broad leaf weeds); which were higher than other weed species, indicated their dominance at 60 days after planting.

At 60 DAP, bispyribac 25 g/ha + ethoxysulfuron 18.75 g/ha -25 DAT, bispyribac 20 g/ha + chlorimuron + metsulfuron (Almix) 4 g/ha- 25 DAT, and pretilachlor 750 g/ha-3 DAT fb ethoxysulfuron 18.75 g/ha-25 DAT recorded lower weeds’ density and dry weight compared to application of single herbicides indicated the necessity of combination of herbicides to manage complex weed flora in transplanted rice. Hand weeding at 25 and 45 DAS had given significantly highest grain (5.9 t/ha) and straw yield (7.4 t/ha) followed by the plots treated with penoxsulam + cyhalofop 135 g/ha–15-20 DAT (5 t/ha) (6.7 t/ha), bispyribac 25g/ha + ethoxysulfuron 18.75 g/ha -25 DAT (5 t/ha) (7.3 t/ha). Unweeded control gave the lowest paddy grain yield (1.8 t/ha) and lowest B:C ratio (1.2) was due to severe competition from all types of weeds.

In Kharif, 2015, at 60 DAP, plots treated with herbicide combinations such as pretilachlor 750 g/ha- 3 DAP fb ethoxysulfuron 18.75 g/ha-25 DAP, bispyribac 20 g/ha + chlorimuron + metsulfuron (Almix) 4 g/ha-25 DAT and bispyribac 25 g/ha + ethoxysulfuron 18.75 g/ha-25 DAT recorded lower weeds’ density and dry weight compared to application of single herbicides indicated the necessity of combination of herbicides to manage complex weed flora in transplanted rice.

The plot treated with pretilachlor 750 g/ha-3 DAT fb ethoxysulfuron 18.7 g/ha-25 DAT recorded significantly higher paddy grain yield (5.15 t/ha) followed by bispyribac 20 g/ha + chlorimuron + metsulfuron (Almix) 4 g/ha-25 DAT (5 t/ha) and these were as par with the two hand weedings (25 and 45 DAP) (5.9 t/ha). Unweeded control gave the lowest paddy grain yield (1.8 t/ha). Bispyribac 20 g/ha + chlorimuron + metsulfuron (Almix) 4 g/ha-25 DAT (3.0), bispyribac 25 g/ha + ethoxysulfuron 18.75 g/ha -25 DAT (2.9) realised higher B:C ratio and hand weeding at 25 and 45 DAS (2.4) whereas, it was only 2.4 in hand weeded plots (Table 3.1.1.1).

KAU, Thrissur

Weeds in the experimental field were Echinochloa spp., Leptochloa chinensis, Cyperus sp., Monochoria vaginalis, Fimbristylis miliacea and Ludwigia parviflora. Weedy rice also occurred in moderate numbers in the field.

Bispyribac-sodium and penoxsulam were significantly effective in reducing the count of Echinochloa spp. Penoxsulam was also effective against Leptochloa chinensis, but bispyribac sodium was ineffective. Triafamone + ethoxysulfuron significantly reduced Leptochloa and Echinochloa spp. population. The second flush of these weeds which emerged after 30 DAT could not be controlled by ethoxysulfuron and almix. However, pendimethalin fb bispyribac-sodium reduced population of Echinochloa spp., though it failed with Leptochloa, which recorded even higher counts than weedy check. Pyrazosulfuron followed by Almix reduced population of Echinochloa spp. significantly as compared with unweeded control, but was not effective against Leptochloa chinensis. Against the broad leaved weed Ludwigia parviflora, combination of pretilachlor and pyrazosulfuron followed by Almix, and triafamone with ethoxy sulfuron were effective.

At 60 DAT, the best treatment to reduce weed population was triafamone combined with ethoxysulfuron. Treatments including penoxsulam and pyrazosulfuron-ethyl followed by Almix were on par with this. There were no phytotoxicity effect on the crop. Grain yield of rice was highest under hand weeding (6.92 t/ha), followed by triafamone combined with ethoxysulfuron (5.96 t/ha) and bispyribac-sodium combined with Almix (5.69 t/ha), which were on par with hand weeding. All treatments were significantly superior to unweeded control (1.29 t/ha). Triafamone + ethoxysulfuron recorded highest B:C ratio of 4.8 followed by bispyribac sodium + Almix (4.2).

PJNCARI, Karikal

Dominant weed flora was Echinochloa crus-galli, Leptochloa chinensis, Eclipta prostrata, Marselia quadrifoliata, Cyperus difformis and Cyperus iria. Application of triafamone+ ethoxysulfuron significantly reduced weed density (0.7 no./m2) and dry weight (0.9 g/m2) and resulted in higher rice yield (5 t/ha). Excellent control of grass, sedge and broadleaved weeds and in particular, deformed growth of Echinochloa sp. was observed due to the triafamone spray. This treatment was followed by the application of penoxsulam + cyhalofop and pretilachlor fb (chlorimuron + metsulfuron) in terms of weed control and rice yield. Post-emergence application of bispyribac-sodium was found ineffective in controlling Marselia quadrifoliata. Unweeded control accounted for 37.2% yield loss in coastal ecosystem. Application of triafamone + ethoxysulfuron was better in terms of B: C ratio (2.8), followed by pre-emergence application of pretilachlor fb chlorimuron + metsulfuron (2.6) and pyrazosulfuron fb chlorimuron + metsulfuron (2.6), respectively (Table 3.1.1.2).

Table 3.1.1.2 Effect of herbicide combinations on grain yield and economics in transplanted rice

UAS, Raichur

Predominant grassy weeds associated with transplanted rice were Echinochloa colona, Echinochloa crus-galli, Cynodon dactylon and Panicum repens, Cyperus iria, Cyperus difformis, Cyperus rotundus and Fimbristylis miliacea among sedges and Eclipta alba, Rotelia densiflora, Marsilea quadrifolia, Sphenoclea zeylanica, Ludwigia parviflora and Commelina benghalensis among broad leaved and aquatic weeds.

At 60 DAT, hand weeding (25 and 45 DAT) recorded lowest total weed density and dry weight (4.39 /m2 and 3.16 g/m2, respectively ) and it was found on par with pyrazosulfuron-ethyl 20 g/ha – 3 DAT fb chlorimuron-ethyl + metsulfuron- methyl 4 g/ha – 25 DAT (5.1 /m2 and 3.5 g/m2, respectively ) as compared to weedy check (11/m2 and 8.3 g/ m2), respectively. Hand weeding twice at 25 and 45 DAT recorded significantly highest total dry matter (83 g/plant), number of tillers (517/m2), number of panicles (389 m2), grain yield (5.1 t/ha), straw yield (6.2 t/ha) and lowest weed index as compared to weedy check but was found on par with treatments comprising of pyrazosulfuron-ethyl 20 g/ha – 3 DAT fb chlorimuron- ethyl + metsulfuron- methyl 4 g/ha – 25 DAT and bensulfuron methyl + pretilachlor 660 g/ha – 3 DAT + hand weeding- 25 DAT. Application of pyrazosulfuron- ethyl 20 g/ha – 3 DAT fb chlorimuron -ethyl + metsulfuron- methyl 4 g/ha –25 DAT recorded the highest benefit cost ratio (2.8).

RAU, Pusa

Lowest weed population, dry weight, highest weed control efficiency (75.9 %) and highest grain yield of rice (5.05 t/ha) were recorded under hand weeding at 25 and 45 DAT which was significantly superior and was at par with pendimethalin 750 ml/ha fb bispyribac-sodium 25 g/ha (4.84 t/ha). The highest weed control efficiency (75.9 %) was recorded under hand weeding at 25 and 45 DAS which There were not any phytotoxic effects on rice crop.The highest net return (` 42,525/ha) and B:C ratio (2.59) was recorded by the treatment pendimethalin 750 ml/ha fb bispyribac-sodium 25 g/ha which was found significantly superior over rest of the treatments.

WS 3.1.2 Herbicide combinations for management of complex weed flora in drum-seeded rice (Puddled)

Cooperating centres: Hyderabad, Bengaluru and Coimbatore

PJTSAU, Hyderabad

Major weed flora consisted of Echinochloa colona, Echinochloa crus-galli and Cyperus rotundus. Lowest weed density was observed during 60 and 90 DAS with hand weeding twice at 20 and 40 DAS except at 30 DAS where the lower weed density was observed with pre-emergence application of pyrazosulfuron-ethyl fb hand weeding at 40 DAS and it was on par with PE application of bensulfuronmethyl + pretilachlor fb HW, pretilachlor + safener fb azimsulfuron as post emergence at 25-30 DAS, pretilachlor + safener fb HW and pyrazosulfuronethyl fb azimsulfuron and was followed by post emergence application of azimsulfuron, bispyribac sodium fb HW, oxadiargyl fb HW and oxadiargyl fb azimsulfuron and similar trend was observed at 60 and 90 DAS.

Significant increase in grain yield was observed with hand weeding twice at 20 and 40 DAS and was on par with pre-emergence application of pyrazosulfuron-ethyl fb hand weeding at 40 DAS, bensulfuron-methyl + pretilachlor fbHW, pretilachlor + safener fb azimsulfuron as post-emergence at 25-30 DAS and pyrazosulfuron-ethyl fb azimsulfuron treatments. Pre-emergence application of pyrazosulfuron-ethyl 20 g fb hand weeding at 40 DAS was effective in efficient weed control and to get higher profit with B.C ratio of 1.4 over hand weeding twice due to reduced cost of cultivation.

UAS, Bengaluru

Drum-seeded rice (dry) Kharif, 2015

Major weed flora observed in the experimental plots was Fimbristylis miliacea and Cyperus difformis (sedge), Paspalum distichum and Echinochloa colona (among grasses). Whereas among broadleaf weeds, major weeds were Dopatrium junceum, Rotala verticillaris, Ludwigia parviflora, Gnaphalium polycoulon and Commelina benghalensis. Among the weed species, densities of E. colona, Fimbristylis miliacea and Commelina benghalensis were more than other weed species.

At 60 DAS, combination of herbicides bensulfuron-methyl 60 g/ha + pretilachlor 600 g/ha fbHW/ MW, bispyribac-sodium 25 g/ha fb HW/MW and oxadiargyl 80 g/ha fb HW/MW reduced the weeds’ density and dry weight comparable to hand weeding at 25 and 45 DAS. Bensulfuron-methyl 60 g/ha + pretilachlor fb HW/MW 600 g/ha (3.8 t/ha, 5.82 t/ha) and bispyribac-sodium 25 g/ha fb HW/MW (3.8 t/ha, 5.7 t/ha) followed by oxadiargyl 80 g/ha fb HW/MW (3.6 t/ha, 5.5 t/ha) recorded grain and straw yields on par with hand weeding (4.0 t/ha, 6.1 t/ha) but significantly higher yields compared to unweeded check and other herbicide treatments. Unweeded control resulted in the lowest paddy grain and straw yields (1.2 t/ha, 2.2 t/ha) owing to severe weed competition. The higher B:C ratio was obtained in pretilachlor 450 g/ha+ safener fb. HW (2.1) followed by pyrazosulfuron-ethyl 20 g/ha fb azimsulfuron 35 g/ha (2.0) compared to unweeded check (1.0).

Drum-seeded rice (dry) summer, 2015

Major weed flora observed in the experimental plots were Fimbristylis miliacea and Scirpus sp.; (sedge), Paspalum distichum and Echinochloa colona (among grasses). Whereas among broadleaf weeds, major weeds were Dopatrium junceum, Rotala verticillaris, Ludwigia parviflora, Gnaphalium polycoulon and Commelina benghalensis.

At 60 DAS, application of combination of bispyribac -sodium 25 g/ha -20 DAS fb hand weeding / mechanical weeding 40 DAS reduced the weed density and dry weight compared with hand weeding treatment whereas other herbicide combinations, viz. bensulfuron-methyl 60 g/ha+ pretilachlor 600 g/ha 5 DAS fb hand weeding /mechanical weeding 40 DAS, and pyrazosulfuron-ethyl 20 g/ha – 8-10 DAS fb hand weeding / mechanical weeding 40 DAS also reduced weed density and dry weight compared and found superior to azimsulfuron, 35 g/ha- 25-30 DAS alone and unweeded control (Table 3.1.2.1).

Bispyribac-sodium 25 g/ha -20 DAS fb hand weeding /mechanical weeding 40 DAS (3.5t/ha, 5.1 t/ha), bensulfuron-methyl 60 g/ha+ pretilachlor 600 g/ha 5 DAS fb hand weeding /mechanical weeding 40 DAS (3.4 t/ha, 4.9 t/ha) and oxadiargyl 80 g/ha – 8-10 DAS fb azimsulfuron 35 g/ha-25-30 DAS (3.3 t/ha, 4.3 t/ha) recorded grain and straw yield on par with hand weeding treatment (3.6 t/ha, 5.2 t/ha). Higher B:C ratio was obtained under pretilachlor + safener 450 g/ha- 3-5 DAS fb hand weeding – 40 DAS (2.1) as compared to unweeded check (1.0) (Table 3.1.2.2).

WS 3.1.3 Herbicide combinations for control of complex weed flora in direct-seeed rice (dry/wet)

Cooperating Centres:

• Dry seeded: Bhubaneswar, Bengaluru, Ranchi, Palampur, Jorhat, Dapoli, Raipur and Thrissur
• Wet seeded: Faizabad, Coimbatore and Pusa

OUAT, Bhubaneswar

The floristic composition of the experimental site was dominated with grasses like Digitaria ciliaris, Cynodon dactylon, Echinochloa colona and broadleaved weeds like Ageratum conyzoides, Cleome viscosa, Celosia argentea Oldenlandia corymbosa, Ludwigia parviflora, Physalis minima and Amaranthus viridis. The dominant sedges observed were Cyperus rotundus and Cyperus iria. Other weeds observed in lower density were Panicum repens, Sporobolus diander, Alternanthera sessils and, Eclipta alba.

Application of pendimethalin fb bispyribac fb manual weeding recorded significantly lowest density at 30 and 60 DAS, but at harvest oxadiargyl fb bispyribac treated plots recorded significantly lowest value of 5.6 per m² followed by pyrazosulfuron fb bispyribac (6.3) and pendimethalin fb bispyribac fb manual weeding (6.6). Application of pendimethalin fb bispyribac fb manual weeding exhibited significantly lowest weed biomass of 1.9, 2.2 and 4.6 g/m² 30,60 DAS and at harvest, respectively followed by oxadiargyl fb bispyribac treatment.

Significantly higher grain yield of 3.4t/ha was obtained with application of pendimethalin fb bispyribac fb manual weeding which was at par with oxadiargyl fb bispyribac (3.3 t), pyrazosulfuron fb bispyribac (3.2 t), pendimethalin fb bispyribac (3.1 t) and pendimethalin fb manual weeding (3.0 t/ha). Highest net return and B:C ratio of Rs.18900/ha and 2.7 were obtained respectively from application of pendimethalin fb bispyribac fb manual weeding followed by oxadiargyl fb bispyribac (Rs17600/ha and 2.7 ).

UAS, Bengaluru

In Kharif, 2015, major weed flora observed in the experimental plots was Cyperus rotundus (sedge), Digitaria marginata, E. colona (among grasses). Whereas, major broadleaved weeds were Phyllanthus niruri, Spilanthes acmella, Commelina benghalensis, Acanthospermum hispida and Portulaca oleracia. Among the weed species, the densities of C. rotundus, D. marginata, E. colona, S. acmella, E. geniculata and A. conyzoides C.benghalensis, O.canum and P.oleracia were more than other weed species indicating their dominance and competitiveness with the direct seeded rice.

Effective control of weeds was noticed at 60 DAS with application of oxadiargyl 100 g/ha – 2 DAS fb bispyribac-sodium 25 g/ha – 25 DAS followed by pendimethlain 1000g/ha (2 DAS) fb bispyribac 25 g/ha – 25 DAS. Three hand weedings (20,40 & 60 DAS) recorded significantly higher paddy grain (3.6 t/ha) and straw yield (6.5 t/ha) compared to all other treatments except pendimethlain 1000g/ha (2 DAS) fb bispyribac 25 g/ha – 25 DAS fb manual weeding – 45 DAS(3.5t/ha) (6.4t/ha), Oxadiargyl 100 g /ha – 2 DAS fb bispyribac-sodium 25 g/ha – 25 DAS(3.4t/ha) (6.1t/ha) (Table3.1.3.1).

In summer, 2015, major weed flora was Cyperus rotundus (sedge), Digitaria marginata, Echinolchloa colona (among grasses). Major broad leaf weeds were Spilanthes acmella, Commelina benghalensis, Ageratum conyzoides, euphorbia geniculata, Ocimum canum, Phyllanthus niruri etc. At 60 DAS, pre-emergence application of pendimethlain 1000g/ha (2 DAS) fb bispyribac 25 g/ha – 25 DAS fb manual weeding – 45 DAS, pendimethlain 1000g/ha (2 DAS) fb bispyribac 25 g/ha – 25 DAS and pyrazosulfuron-ethyl 20 g/ha – 3 DAS fb bispyribac-sodium 25 g/ha – 25 DAS reduced the weeds’ density and dry weight comparable to three mechanical weeding conoweeder. (Table 3.1.3.2).

AAU, Jorhat

Weeds appeared in the field nearly 10 days after sowing of rice and the first emerged species were Cynodon dactylon and Eleusine indica. At 30 DAS, altogether 5 grasses, 5 broadleaved species and one sedge (Cyperus rotundus) were recorded in the experiment. Out of these two other grasses were Digitaria setigera, Axonopus compressus and Panicum repens and the broadleaved weeds were Ageratum houstonianum, Borreria articularis, Commelina diffusa, Ludwigia linifolia and Sonchus wightianus. Weeds emerged nearly 30 to 50 days late and prevailed thereafter were mostly broadleaved viz. Amaranthus viridis, Impatians balsamona, Melochia corchorifolia, Mimosa diplitricha, Mimosa pudica and Phylanthus fraternus. However, amongst all these species, the grasses along with Ageratum and Melochia dominated the entire vegetation.

Weed density was lowest due to pendimethalin 1000 g/ha fb manual weeding (25DAS) and pendimethalin 1000 g/ha fb bispyribac-Na 25 g/ha + manual weeding (45 DAS) at 20 and 40 days after sowing. Pendimethalin 1000 g/ha fb manual weeding(25DAS) maintained a lower weed density up to the harvesting stage which was at par with weed free (hand weeding 20, 40 and 60 DAS) at 60 DAS and mechanical weeding 20, 40 and 60 DAS at 60 DAS and harvest. Weed dry weight also affected in similar manner and pendimethalin 1000 g/ha fb manual weeding (25DAS) was at par with mechanical weeding 20, 40 and 60 DAS and Weed free (hand weeding 20, 40 and 60 DAS) at all stages up to 60 DAS.

Taller plants, higher number of tiller, panicle number and panicle length and filled grain caused increased grain yield due to Pendimethalin 1000 g/ha fb manual weeding (25DAS) and pendimethalin 1000 g/ha fb bispyribac-Na 25 g/ha + manual weeding (45 DAS).

DBSKKV, Dapoli

During the first year of the experimentation (2012) the  use of pendimethalin fb manual weeding significantly reduced the growth of monocots as compared to use of bispyribic-Na, pendimethalin fb bispyribic-Na, pyrazosulfuron fb bispyribic –Na,  weedy check and remained at par with rest of the treatments, while, during the year 2013, 2014. 2015 and in pooled results, the use of pendimethaline fb manual weeding recorded significantly lowest weed growth than rest of the treatment except pendimethalin fb bispyribic-Na fb manual weeding and weed free check. Various weed control measures tried did not significantly influenced growth of BLWS during individual years as well as in pooled results at 60 DAS.

Weed free check produced significantly higher grain and straw yield (3.88 and 4.68 t/ha), respectively over rest of the treatments followed by use of pendimethalin fb manual weeding (3.67 and 4.38 t/ha) and pendimethalin fb bispyribic-Na fb manual weeding (3.58 and 4.39 t/ha) which were at par with each other.  Thus compared to best treatment of weed free check the percent reduction in the grain yield, (WCI) was found to be least in case of pendimethalin fb manual weeding (5.26%) followed by pendimethalin fb bispyribic-Na fb manual weeding (7.70 %). The highest net returns of Rs. 13,887/ha were obtained with the application of  pendimethalin (PE) fb manual weeding, followed by weed free check (HW at 20, 40 and 60 DAS) Rs. 10,698/ha with B:C ratio of 1.28 and 1.19, respectively.

 

KAU, Thrissur

In wet direct seeded rice, the major weeds were Sacciolepis interrupta, a grass, and various species of Cyperus, a sedge. Other weeds occurring in the field were Echinochloa spp., Cyanotis axillaris, Lindernia sp., Fimbristylis miliacea, and Ludwigia parviflora.  There was severe infestation of weedy rice in all the treatment plots, which contributed to low yield. Most herbicide combinations were ineffective in controlling Sacciolepis interrupta, while all were effective in controlling Cyperus spp. The main reason for ineffective control of Sacciolepis was its late emergence. Bispyribac-sodium, was ineffective against Sacciolepis. Only those treatments which included hand weeding at 45 or 60 DAS could control this weed. All treatments were superior to unweeded control in the control of Cyperus spp. The lowest dry matter production of weeds was in the hand weeded control, which was on par with application of pendimethalin followed by Bispyribac-sodium or hand weeding. Pendimethalin followed by manual weeding recorded the highest WCE (93.26%), followed by hand weeding (92.04%) and pendimethalin followed by bispyribac sodium followed by hand weeding (90.60%).

Highest grain yield of 33 t/ha was recorded in the hand weeding treatment. Treatments,  bispyribac -sodium , pyrazosulfuron- ethyl followed by Bispyribac- sodium  and Bispyribac- sodium + [chlorimuron ethyl + metsulfuron methyl] were significantly inferior. However lowest grain yield was recorded in unweeded control. There were no detectable phytotoxic effects on the crop. After hand weeding, lowest uptake of N, P and K by weeds were recorded in the treatment pendimethalin fb hand weeding (8.37, 1.62 and 1.26 kg/ha, respectively), which also recorded lowest dry matter production. This was followed by the treatment pendimethalin fb bispyribac sodium fb hand weeding. Highest B:C ratios of 2:1 were recorded in Bispyribac- sodium and oxadiargyl fb bispyribac -sodium. Hand weeding resulted in a B:C ratio of 1.1 The lowest value of 0.5 was recorded in the unweeded control.

UAS, Raichur

Predominant weed flora of dry direct seeded rice was grassy weeds viz., Dinebra retroflexa, Echinochloa colona, Panicum repens, Chloris barbata and Leptochloa chinensis. Among sedges Cyperus difformis, Cyperus iria and Fimbristylis miliaceae and among broadleaved weeds Ammania baccifera, Cyanotis axillaris, Eclipta alba, Phyllanthus niruri and Amaranthus viridis were present.

At 60 DAS, hand weeding thrice at 20, 40 and 60 DAS recorded lower total weed density and dry weight compared to all other treatments except with the treatment receiving pendimethlain 1000 g /ha (2 DAS) fb bispyribac 25 g/ha – 20 DAS fb manual weeding – 45 DAS. Herbicide combinations such as pyrazosulfuron- ethyl 20 g/ha – 3 DAS fb bispyribac-sodium 25 g/ha – 25 DAS, penoxsulam+ cyhalofop 135 g/ ha – 15 DAS, pendimethlain 1000 g /ha (2 DAS) fb bispyribac 25 g/ha – 25 DAS, mechanical weeding (passing conoweeder – 20, 40 & 60 DAS) and oxadiargyl 100 g/ha – 2 DAS fb bispyribac-sodium 25 g/ha – 25 DAS recorded lower weeds’ density and dry weight next to hand weeding thrice. While the treatments such as bispyribac-sodium 25 g/ha – 20 DAS + chlorimuron ethyl + Metsulfuron- methyl 4 g /ha -20 DAS, pendimethlain 1000 g /ha (2 DAS) fb manual weeding -25 DAS and butachlor 1250 g/ha- 6DAS fb bispyribac 25 g/ha – 25 DAS recorded on par weeds’ density and dry weight.

Three hand weedings (20, 40 & 60 DAS) recorded significantly higher paddy grain and straw yield (4.25 and 5.31 t/ha) compared to all other treatments except pyrazosulfuron ethyl 20 g ai/ha – 3 DAS fb bispyribac-sodium 25 g ai/ha – 25 DAS (4.16 and 5.20 t/ha), pendimethalin 1.0 kg/ha – 2 DAS fb bispyribac sodium 25 g ai/ha – 20 DAS with manual weeding – 45 DAS (4.04 and 5.05 ton/ha), penoxsulam+ cyhalofop 135 g/ ha – 15 DAS (3.99 and 4.98 ton/ha) and pendimethlain 1000 g ai/ha (2 DAS) fb bispyribac 10 SC 25 g ai/ha – 25 DAS (3.90 and 4.88 ton/ha) with which it was found on par.

Cooperating Centres: Ludhiana, Pantnagar, Kanpur, Faizabad, Palampur, Gwalior, Pusa, Ranchi, Anand, Parbhani, Bikaner, Dharwad and Jammu

PAU, Ludhiana

Phalaris minor, Medicago denticulata, Rumex dentatus and Chenopodium album were major weeds in wheat. Tank-mix of pendimethalin + metribuzin, pinoxaden + metribuzin, pre-mix of mesosulfuron + iodosulfuron, pendimethalin 0.75-1.0 kg fb sulfosulfuron 0.018 kg, metribuzin 0.21 kg/ha alone recorded >80% WCE, provided effective control of all the weeds and significantly reduced the weed dry matter, and nutrient depletion by weeds, as compared to unweeded control. All the weed control treatments except clodinafop 60 g/ha recorded significantly higher wheat grain yield and yield attributes than unweedeed control. Tank-mix application of pinoxaden+metsulfuron recorded the highest wheat grain yield and was at par with all other herbicidal treatments except pendimethalin 0.75 kg and clodinafop 0.06 kg/ha. This tank-mix also recorded the highest net returns and B:C which was comparable to tank-mix of pendimethalin 1.0 kg + metribuzin 0.175 kg/ha, pendimethalin 1.0 kg fb sulfosulfuron 0.018 kg/ha and metribuzin 0.21 kg /ha treatments. The study concluded that sequential/tank-mix application of pre- and or post-emergnece grass and broadleaf killers could be adopted for broad-spectrum control of weeds in wheat.

NDUAT, Faizabad

Dominant weeds in the weedy check plot viz., Phalaris minor, Chenopodium album, Melilotus alba, Anagallis arvansis, Vicia sativa, Fumaria parviflora  and Rumex  dentatus were recorded. Application of pendimethalin 1 kg  + metribuzin 0.175 kg/ha applied as pre-emergence followed by pendimethalin+ sulfosulfuron (1.0+0.018 kg/ha, PRE & POE), sulfosulfuron+metsulfuron  (0.03+0.002 kg/ha), pinoxaden+ metsulfuron (premix) (0.06+0.004 kg/ha, 5WAS), mesosulfuron+ iodosulfuron  (0.012+0.0024 kg/ha, 5WAS) and clodinafop+ metsulfuron (premix) (0.06+0.004 kg/ha) controlled all  types of weed very effectively as compared to single herbicide molecule application. Among the  different weed control measures maximum WCE was recorded (100%) under hand weeding treatment followed by pendimethalin 1.0 kg/ha + metribuzin 0.175 kg/ha (81.6%).

Highest grain and straw yield (4217 and 6140 kg/ha) was recorded with pendimethalin + metribuzin (1.0+0.175 kg/ha, PRE) application  which was at par with pendimethalin+ sulfosulfuron (1.0+0.018 kg/ha, PRE & PO), sulfosulfuron+metsulfuron  (0.03+0.002 kg/ha, 5WAS), pinoxaden+ metsulfuron (premix) (0.06+0.004 kg/ha, 5WAS), mesosulfuron+ iodosulfuron (0.012+0.0024 kg/ha, 5WAS) and clodinafop+ metsulfuron (Premix)  (0.06+0.004 kg/ha, 5WAS) treatments and significantly superior with sulfosulfuron (0.025 kg/ha, PO), metribuzin (0.21 kg/ha, PRE), pendimethalin (0.75 kg/ha, PRE) and clodinafop (0.06 kg/ha, PO) treatments. Pendimethalin + metribuzin (1.0 + 0.175 kg/ha, PRE) treatment recorded maximum BCR (Rs. 1.96) than other weed control measures.

 

RVSKKV, Gwalior

Weed flora in the experimental field comprised of grassy weeds Phalaris minor, Cyperus rotundus and broad leaves weeds Chenopodium album,  Spergula arvensis,  Convolvulus arvensis and Rumex dentatus. Lowest weed dry weight was recorded in 2 HW and it was at par with all the weed control treatments.  The highest weed control efficiency was achieved under 2 HW (91.74%) followed by mesosulfuron + idosulfuron 0.012 + 0.0024 kg/ha (87.61%), pinoxaden + metsulfuron   0.06 + 0.004 kg/ha (87.15%) and sulfosulfuron + metsulfuron 0.03 + 0.002 kg/ha (86.23%). Among alone application of herbicides sulfosulfuron gave highest WCE of 79.82%.

Highest grain yield of 5.03 t/ha was recorded in 2 HW followed by pinoxaden + metsulfuron (0.06 + 0.004 kg/ha), sulfosulfuron + metsulfuron (0.03 + 0.002 kg/ha) and mesosulfuron + iodosulfuron (0.012 +0.0024) and they were at par to each other. Two hand weedings at 30 and 60 DAS yielded 62.8% higher grain yield over weedy check. Among the alone application of herbicide sulfosulfuron gave significantly higher grain yield as compared to pendimethalin,  metribuzin and clodinafop.  Highest net income and B:C ratio of Rs. 71182/ha and 3.69 was obtained in treatment pinoxaden + metsulfuron (pre mix) followed by sulfosulfuron + metsulfuron (Rs. 70128/ha and 3.67) and metsulfuron + iodosulfuron (Rs. 68961/ha and 3.53).

 

AAU, Anand

Major monocot weeds observed in the experimental fields were Phalaris minor, Avena fatua, Asphodelus tenuifolius, Setaria tomentosa and Cyperus iria. The dicot weeds were Chenopodium album, Chenopodium murale, Melilotus indica, Amaranthus viridis, Oldenlandia umbellata and Digera arvensis. Among weed management practices, the treatment hand weeding carried out at 30 and 60 DAS and pre-emergence application of pendimethalin fb sulfosulfuron showed significantly the lower total weed density and weed dry biomass. The highest grain (4454 kg/ha) and straw (7035 kg/ha) yield were recorded under hand weeding carried out at 30 and 60 DAS, but it was at par with clodinafop + metsulfuron, sulfosulfuron + metsulfuron, pinoxaden + metsulfuron, pendimethalin fb sulfosulfuron, sulfosulfuron, clodinafop and mesosulfuron + iodosulfuron. Nutritient depletion by the weeds in unweeded control treatment to the tune of 57.63 kg N, 51.03 kg P and 130.87 kg potash was recorded at harvest.

RAU, Pusa

Dominant weed species observed in the experimental field were, Avena fatua, Cynodon dactylon, Phalaris minor, Cyperus rotundus, Anagalis arvensis, Chenopodium album, Cirsium arvense, Convolvulus arvensis, Eclipta alba, Fumaria parviflora, Lathyrus aphaca, Launia pinnatifida, Melilotus alba, Physalis minima, Rumex dentatus and Vicia hirsute.

Lowest weed density (19/m²) and weed dry weight (8.83 g/m²) were recorded by sulfosulfuron 0.03 kg/ha +metsulfuron 0.002 kg/ha at 5 WAS which were statistically at par with clodinafop 0.06 kg/ha + metsulfuron (Premix) 0.004 kg/ha at 5 WAS, pinoxaden 0.06 kg/ha + metsulfuron 0.004 kg/ha (premix) at 5 WAS and pendimethalin 1.0 kg/ha (PE) fb sulfosulfuron 0.018 kg/ha (POE) and significantly superior over rest of the treatments. Among different herbicide combinations, the highest grain yield of wheat was recorded by sulfosulfuron 0.03 kg/ha +metsulfuron 0.002 kg/ha at 5 WAS (4.58 t/ha) which was statistically at par with pendimethalin 1.0 kg/ha (PE) fb sulfosulfuron 0.018 kg/ha (POE) (4.42 t/ha), pinoxaden 0.06 kg/ha + metsulfuron 0.004 kg/ha (Premix) at 5 WAS (4.37 t/ha) and clodinafop 0.06 kg/ha + metsulfuron 0.004 kg/ha (Premix) at 5 WAS (4.44 t/ha) and found significantly superior over rest of the treatments. Highest B:C ratio (3.26) was recorded by sulfosulfuron 0.03 kg/ha +metsulfuron 0.002 kg/ha at 5 WAS which was statistically at par with clodinafop 0.06 kg/ha + metsulfuron 0.004 kg/ha (Premix) at 5 WAS (3.14).

BAU, Sabour

Major weed flora in experimental field was Chenopodium album, Rumex dentatus, Medicago denticulate, Anagallis arvensis, Coronopus didymus and Fumaria parviflora. Polypogon monosplensis and Phalaris minor were dominant grassy weeds. Among the herbicidal treatments, maximum weed dry matter at 60 DAS was recorded with sulfosulfuron 25 g/ ha as post emergence, while minimum weed dry matter was recorded with pinoxaden 0.06 kg / ha + metsulfuron (Premix) 4 g/ ha as PoE followed by clodinafop 60 g / ha + metsulfuron (Premix) 4 g/ ha as PoE. Maximum grain yield of wheat (4.12 t/ha) was also recorded with application of pinoxaden 0.060 g/ ha + metsulfuron (Premix) 4 g / ha as PoE followed by clodinafop 60 g/ ha + metsulfuron (Premix) 4 g/ ha as PoE . Maximum B: C ratio of 3.00 was obtained with pinoxaden 60 g/ ha + metsulfuron (Premix) 4 g / ha as PoE.

WS 3.3.1 Integrated weed management with pre- and post-emergence herbicides in turmeric

Cooperating centres: Hisar, Palampur, Faizabad, Pusa, Jorhat, Ranchi, Bengaluru, Pantnagar, Raipur and Puducherry

CCSHAU, Hisar

Weed flora of the field consisted of Dactyloctenium aegyptium, Brachiaria reptans, Digitaria reptans, Eragrostis tenella among grasses; Trianthema monogyna among broadleaf weeds (BLW); and Cyperus rotundus among sedges. Treatments with straw mulch were found most effective against all type of weeds particularly against broadleaf weeds and sedges. Fenoxaprop provided effective control of grassy weeds as post-emergence herbicide. Glyphosate at 7.5 ml/litre of water (directed spray) provided effective control of most of the weeds at the time of application. Metribuzin or pendimethalin or atrazine fb mulching + one hand weeding provided excellent control of weeds and crop growth was also visibly better under these treatments. Hence, metribuzin 700 g/ha or pendimethalin 1000 g/ha or atrazine 750 g/ha fb mulching+ hand weeding at 75 DAS were realized to be the best options for effective weed control in turmeric.

NDUAT, Faizabad

Weed flora of the experimental field consisted of Echinochloa species, Dactyloctenium aegyptium and Eleusine indica among grasses Ludwigia sp., Commelina benghalensis, Ammannia baccifera, Ageratum conyzoides and Solanum nigrum among broad leaf weeds and Cyperus rotundus and Fimbristylis among sedges. At 60 DAP stage, PE metribuzin at 0.7 kg/ha fb straw mulch of 10 t/ha on 10 DAP fb one HW on 75 DAP, PE pendimethalin at 1.0 kg/ha fb straw mulch at 10 t/ha on 10 DAP fb one HW on 75 DAP, POE glyphosate at 7.5 ml/lit on 25 DAP fb two HW on 45 and 75 DAP and PE oxyfluorfen at 0.30 kg/ha fb two HW on 45 and 75 DAP in treatments provided very good control of all type of weeds in turmeric. However, atrazine + straw mulch + HW also provided effective control of weeds but it showed phytotoxicity on the crop. Oxyfluorfen 30 g and oxadiargyl 25 g/ha fb 2 HW proved very effective control to all the weeds and showed no phytotoxicity on the crop.

AAU, Jorhat

Grasses like Panicum repens and to some extent Saccharum spontaneum and broadleaved weed Scoparia dulcis appeared as the most troublesome weeds. Other grasses of this crop were Cynodon dactylon, Eleusine indica and Digitaria setigera. Broadleaved species, Mimosa diplotricha var. innermis, Borreria articularis and Ageratum houstonianum were rather common than Alternanthera sessilis, A. philoxeroides, Cuphea balsamina and Spilanthes paniculata. Sedges, Cyperus brevifolius and Fimbristylis bis-umbellata were seen during the rainy days only. Among these, B. articularis, E. indica and M. diplotricha were the early emerged species in the field.

Lowest density and dry weight of weeds were found with pendimethalin 1000 g/ha fb straw mulch 10 t/ha fb hand weeding 75 DAP. These treatments were at par with hand weeding 25, 45 and 75 DAP. The highest rhizome yield was obtained from pendimethalin 1000 g/ha fb straw mulch 10 t/ha fb hand weeding 75 DAP closely followed by metribuzin 700 g/ha fb straw mulch 10 t/ha fb hand weeding 75 DAP (Table 3.3.1.1).

BAU, Ranchi

Broadleaved weeds accounted maximum number (906/m2) followed by narrow (367/m2) and sedges (159/m2) in weedy check treatment at 90 DAP. Total weed density and dry matter accumulation was reduced with application of glyphosate 7.5 ml/lit 25 DAP fb 2 hand weeding (45 and 75 DAP) similar to oxyfluorfen fb 2 hand weedings (45 and 75 DAP), oxadiargyl fb 2 hand weedings (45 and 75 DAP), glyphosate 25 DAP fb 2 hand weeding (45 and 75 DAP) and hand weeding (25, 45 and 75 DAP) at 30 DAP, while at 90 and 150 DAP application of metribuzin fb fenoxaprop + metsulfuron (45 DAP) significantly reduced total weed density and dry matter accumulation compared to rest of the treatments except pendimethalin fb fenoxaprop + metsulfuron.

UAS, Bengaluru

Major weed flora was Cyperus rotundus, Scirpus sp. (among sedges), Cynodon dactylon, Echinochloa colona (among grasses); Spilanthes acmella, Portulaca oleracea, Parthenium hysteropnorus, Phyllanthus niruri, Euphorbia geniculata (broadleaf weeds) were higher than other weed species, indicated their dominance from the beginning of the crop cycle.

At 75 DAP pendimethalin 0-5 DAP fb 2 HW 45 and 75 DAP, oxyfluorfen 0-5 DAP fb two HW 45 and 75 DAP, atrazine 0-5 DAP fb two HW45 and 75 DAP, metribuzin fb 2 hand weeding 0-5 DAP fb two HW45 and 75 DAP and oxadiargyl 0-5 DAP fb two HW45 and 75 DAP reduced the weeds density and dry weight significantly and the herbicide treatments were superior to unweeded control with regards to weed density and dry weight.

Higher rhizome yield was obtained with application of pendimethalin fb 2 HW 45 and 75 DAP (23.2 t/ha), oxyfluorfen fb two HW 45 and 75 DAP (22.5 t/ha). Unweeded control gave the lowest fresh rhizome yield (6.4 t/ha). Higher B:C ratio was obtained under pendimethalin fb 2 HW 45 and 75 DAP(2.7), oxyfluorfen fb two HW 45 and 75 DAP (2.6) and atrazine fb two HW 45 and 75 DAP (2.6 each), whereas , B:C ratio was 2.4 in hand weeding treatment due to higher cost of cultivation. Unweeded check failed to realize any benefit (-0.9) (Table 3.3.1.2).

GBPUAT, Pantnagar

Dominant weed species in the weedy plot at 75 DAP were E. colona (8.2%), D. sanguinalis (17%), D. aegyptium (6.9%), E. indica (11.3%), T. monogyna (2.5%) and C. rotundus (54.1%). Least total dry matter accumulation of grassy weeds was recorded with application of pendimethalin fb straw mulch at 10 t/ha fb 1 HW at 75 DAP which was at par with the application of metribuzin at fb straw mulch at 10.0 t/ha fb 1 HW at 75 DAP and atrazine fb straw mulch at 10 t/ha fb 1 HW at 75 DAP. Among all the weed management practices, highest weed control efficiency was recorded with pendimethalin fb straw mulch at 10 t/ha fb hand weeding at fb followed by metribuzin fb straw mulch fb1 HW at 75 DAP.

 Application of pendimethalin fb straw mulch 10 t/ha supplemented with 1 HW at 75 DAP attained highest turmeric yield (33 t/ha) which was significantly superior to all other combination treatments except application of metribuzin at fb straw mulch at 10 t/ha supplemented with 1 HW at 75 DAP. However, the highest gross return (` 6,60,000 /ha), net return (` 5,39,236/ha) and B:C ratio of 4.4 was obtained with application of pendimethalin fb straw mulch at fb10 t/ha along with 1 HW followed by metribuzin at fb straw mulch at fb 10 t/ha supplemented with 1 HW at 75 DAP.

RAU, Pusa

Lowest weed dry weight (7.1 g/m2) was recorded under hand weeding thrice (HW at 25, 45 and 75 DAP) which was significantly superior over rest of the treatments except metribuzin 0.7 kg/ha at 0-5 DAP fb 2 hand weeding at 45 and 75 DAP. The highest weed control efficiency (89.9%) was recorded with hand weeding thrice (HW at 25, 45 and 75 DAP) which was closely followed by metribuzin 0.7 kg/ha fb 2 hand weeding (HW at 45 and 75 DAP) (87.4%), metribuzin 0.7 kg/ha fb fenoxaprop + metsulfuron 67+4 g/ha at 3 DAP fb 45 DAP (78.1%). There were no phytotoxic effects on the crop. The highest rhizome yield of turmeric (47.7 t/ha) was recorded under the treatment hand weeding thrice at 25, 45 and 75 DAP which was statistically at par with metribuzin fb 2 hand weedings at 45 and 75 DAP (46.8 t/ha), metribuzin fb fenoxaprop + metsulfuron at 3 DAP fb45 DAP (46.34 t/ha). Highest net return (` 2,20,708/ha) and B:C ratio(3.1) were recorded by metribuzin 0.7 kg/ha fb fenoxaprop + metsulfuron at 3 DAP fb 45 DAP which were statistically at par with metribuzin followed by two hand weedings.

WS 3.3.2 Integrated control of complex weed flora in garlic

Cooperating centres: Ludhiana, Pantanagar, Faizabad, Anand. Bengaluru and Raipur

PAU, Ludhiana

Rumex dentatus, Coronopus didymus, Oenothera laciniata, Phalaris minor and Medicago denticulata were major weeds in gralic. Uniform spreading of paddy straw mulch at 5 t/ha significantly reduced density of M. denticulata, C. didymus, P. minor and O. laciniata, and weed biomass compared to without mulch. Straw mulch at 7.5 t/ha further reduced weed density and biomass significantly compared to mulch 5 t/ha. The WCE at mulch 5 and 7.5 t/ha was 20 and 66%, respectively, compared to without mulch. Similar results were recorded for nutrient depletion by weeds at harvest.Among weed control treatments, pendimethalin oxyfluorfen and 2 hand hoeing significanlty reduced population of all weeds and weed biomass compared to weedy check. The WCE under these three treatments was >93%.

Mulch at 7.5 t/ha recorded significantly higher garlic clove yield and economic returns than 5 t mulch/ha. B:C ratio varied from 0.7 under without mulch to 1.0 under 5 t and 1.5 under 7.5 t mulch/ha. Among weed control treatments, pendimethalin, oxyfluorfen and 2 hand hoeings significantly improved garlic yield, yield attributes and economic returns than weedy check. Garlic clove yield under herbicides and hand hoeing treatments were at par, however, the economic return under herbicides treatments were higher compared to hand hoeing owing to higher cost of manual labor. The integration of herbicides or hand hoeings with 7.5 t mulch/ha recorded significantly higher garlic yield compared to when these were integrated with 5 t mulch/ha or without mulch.

GBPUAT, Pantnagar

Dominant weed species in the experimental plot were P. minor (18.6%), A. ludoviciana (3.0%), P. monspeliensis (14.7%) among grassy weeds, M. denticulata (6.6%), M. alba (6.3%), C. didymus (25.6%), P. plebeium (12.5%), C. album (3.4%), A. arvensis (1.7%), R. acetocela (2.0%), F. parviflora (1.3%) among BLWs and C. rotundus (4.4%) as sedge at 75 DAS.

Population of all grassy as well as non-grassy weeds except R. acetosela, F. parviflora and C. rotundus were significantly reduced by the application of rice straw mulch at 5 t/ha over without mulch. There was complete control of P. minor and A. ludoviciana with twice hand weeding whereas P. monspeliensis was completely controlled with application of pendimethalin applied at 1 kg/ha. Pendimethalin and oxyflurofen at as pre-emergence provided effective control of P. plebeium and R. acetocela. Highest and significantly high yield (29.5 q/ha) and yield attributing characters like number of bulb (19.5/m2), diameter of bulb (8.4 cm) and bulb weight (13.4 g) were achieved with the application of mulch material (5 t/ha) over without straw mulch Both the recommended herbicides were found comparable in achieving the bulb yield of garlic crop.

NDUAT, Faizabad

Application of mulch at 10 t/ha reduced the weed population and recorded significantly lower weed density, dry weight, weed control efficiency and highest growth and yield of garlic as compared to without mulch plot. Maximum weed control effeciency (71.6%) was recorded with 10 t/ha mulch treatment followed by 5 t/ha. Application of oxyflurofen 0.223 kg/ha recorded significantly lower weed count, weed dry weight, higher weed control efficiency, growth and yield of garlic than weedy check but this was at par with pendimethalin 1 kg/ha application. Maximum BC ratio (1.4) was recorded under the paddy straw mulch 10 t/ha + pendimethalin 1 kg/ha pre-emergence treatments followed by paddy straw mulch 10 t/ha + oxyflurofen 0.223 kg/ha pre-emergence (1.3), respectively. No herbicide caused phytotoxicity on garlic crop.

AAU, Anand

The major dicot weeds of experimental field were Chenopodium album, Chenopodium murale, Digera arvensis, Melilotus indica, Oldenlandia umbellata, Phylanthus niruri and Boerhavia repanda. Monocot weeds were Dactyloctenium aegyptium, Commelina benghalensis, Digitaria sanguinalis, Eleusine indica, Phyllanthus niruri, Cyperus iria and Cyperus rotundus.

Weed density and weed dry biomass was lower in paddy straw mulch 5.0 t/ha. While these were significantly lowest in manual weeding carried out at 20 and 40 DAP, but remained at par with preemergence application of oxyfluorfen for dicot weed dry biomass. Bulb yield of garlic was significantly influenced by weed management treatments and the highest bulb yield of garlic (10.4 t/ha) was obtained in manual weeding at 20 and 40 DAP. Interaction effect of mulching and weed management practices was found significant and the highest bulb yield of garlic was obtained in the combination of manual weeding at 20 and 40 DAP with no paddy straw mulch, but it was at par with the combination of mulching with manual weeding at 20 and 40 DAP and oxyfluorfen. Highest B:C ratio was obtained with mulching (5.0), hand weeding at 20 and 40 DAP (6.4) and interaction of paddy straw mulch 5.0 t/ha and hand weeding at 20 and 40 DAP (6.5). NPK uptake by weeds was lowest in the manual weeding carried out at 20 and 40 DAP treatment followed by oxyfluorfen .

UAS, Bengaluru

Major weed flora was Cyperus rotundus, (among sedges), Echinochloa crus-galli, Cynodon dactylon (among grasses), whereas, among broad leaf weeds, major weeds were Ageratum conyzoides, Acanthospermum hispidum, Borrearia articularis, Euphorbia hirta at 75 DAP.

At 75 DAP, hand weeding treatment recorded significantly lower weed density and weed dry weight followed by oxadiargyl 140 g/ha, oxyflurofen 0.223 kg/ha pre-emergence and pendimethalin 1.0 kg/ha pre-emergence herbicide treatments. Significantly higher bulb yield was obtained under oxadiargyl 140 g/ha (6.2 t/ha) which were on par with manual weeding (6.0 t/ha). The bulb yield (0.6 t/ha) was very low in weedy check plots. Use of herbicides was cheaper than hand weeding. It was observed that higher B:C ratio was obtained in oxadiargyl with and without paddy straw mulch (4.3 and 4.2) followed by oxyfluorfen (3.9) as compared to weedy check (0.4).

WS 3.3.3. Integrated weed management in ginger

Cooperating centres: Thrissur, Ranchi, Bhubaneaswar, Pusa, Jorhat, Faizabad and Raipur

BAU, Ranchi

Broadleaved weed population was maximum (101/m²) followed by narrow (74/m²) and sedges (47/m²) in weedy check treatment. Two years study revealed that glyphosate 0.80 kg/ha + oxyfluorfen 0.2 kg/ha applied just before emergence of sprouts of ginger (T7) was more effective in controlling weeds (weed control efficiency 90%) of ginger in all the growth stages of ginger as a result it produced maximum ginger rhizome yield (29 t/ha), net return (Rs 9, 52,230 /-) and B:C ratio (4.59 ).

OUAT, Bhubaneswar

Application of glyphosate fb pendimethalin recorded lowest weed population at all the growth stages followed by glyphosate fb oxyfluorfen. Weed free treatment (HW at 20, 40, 60 and 90 DAS) recorded significantly highest yield of 27.5 t/ha where as weedy check treatment recorded the lowest yield (11.5 t/ha). Among different herbicide combinations, significantly higher grain yield of 27.2 t/ha was obtained with application of glyphosate fb pendimethalin which was at par with glyphosate fb oxyfluorfen (26.7 t/ha). Highest net return and B:C ratio of Rs.185426/ha and 3.78 were obtained respectively from application of oxadiargyl fb bispyribac weeding followed by pendimethalin fb bispyribac (Rs17600/ha and 2.72 ).

AAU, Jorhat

Scoparia dulcis and Mimosa diplotricha were the most troublesome weeds in the experiment almost all along the cropping period. Mimosa pudica, Cuphea balsamona, Ageratum houstonianum and Borreria articularis appeared late but prevailed in the field till harvest of the crop. Problematic grasses were Panicum repens, Cynodon dactylon and Digitaria setigera and sedges were Cyperus rotundus and Cyperus tenuispica.

Lowest weed density and dry weight were recorded with pendimethalin 1.5 kg/ha fb hand weeding 30-35 DAP followed by oxyfluorfen 0.20 kg/ha fb hand weeding 30-35 DAP. These two treatments brought about significantly lower weed density till 60 days after planting as compared to hand weeding twice. At harvest, there was no significant difference among the treatments in respect of weed density. Plant growth characteristics like plant height, number of tillers, number of leaves and yield attributes like number of fingers and rhizome length were highest due to pendimethalin 1.5 kg/ha fb hand weeding 30-35 DAP , Hand weeding 30 and 60 DAP and oxyfluorfen 0.20 kg/ha fb hand weeding 30-35 DAP. Better growth and yield attributes were reflected in achieving higher rhizome yield under these three treatments.

RAU, Pusa

Lowest weed dry weight was recorded under hand weeding twice (HW at 30 and 60 DAP) treatment which was statistically at par with glyphosate 0.80 + pendimethalin 1.5 kg/ha and glyphosate 0.80 + oxyfluorfen 0.2 kg/ha at Just before emergence of sprouts of ginger and significantly superior over rest of the treatments. The highest rhizome yield (22.4 t/ha) was recorded by hand weeding twice at 30 and 60 DAP which was statistically at par with glyphosate 0.80 + oxyfluorfen 0.2 kg/ha (21.32 t/ha), glyphosate 0.80 + pendimethalin 1.5 kg/ha at just before emergence of sprouts of ginger (19.95 t/ha). The highest B:C ratio (2.07) was recorded by glyphosate 0.80 + oxyfluorfen 0.2 kg/ha at just before emergence of sprouts of ginger which was statistically at par with, hand weeding twice (HW at 30 and 60 DAP) (2.00), glyphosate 0.80 + pendimethalin 1.5 kg/ha at Just before emergence of sprouts of ginger (1.93) and Pendimethalin 1.5 kg/ha after planting but before mulching fb hand weeding at 30-35 DAP (1.76).

CAU, Pasighat

Major weeds observed in experimental field were Cynodon dactylon, Digitaria sanguinalis, Panicum sp., Echinochloa spp., Eleusine indica, Cyperus spp., Commelina benghalensis, Murdania kiosak, Urena lobata, Ageratum conyzoids, Spilanthes acmella, Sida acuta, etc. Application of oxyfluorfen supplemented with hand weeding at 30 DAP fb mulching showed a reduction in weed dry weight and increased WCE (59.4%).Hand weeding twice at 30 DAP and 60 DAP resulted in significantly higher number of fingers per rhizome which was at par with application of oxyfluorfen alone fb mulching, application of pendimethalin supplemented with one hand weeding at 30 DAP fb mulching, application of  oxyfluorfen supplemented with one hand weeding at 30 DAP fb mulching and application of glyphosate + pendimethalin. Hand weeding twice at 30 DAP and 60 DAP recorded significantly higher fresh rhizome yield (9.4 t/ha) than un-weeded control and application of pendimethalin alone fb mulching. It was statistically at par with remaining other weed control treatments. Ginger crop performs well under Arunachal Pradesh conditions if planting is completed by mid May. Due to late planting, crop produced low yield than average yield (8.4 t/ha) of the state. No any visual phytotoxicity was observed.

Higher net return of Rs 58700 was recorded in plots hand weeded twice at 30 DAP and 60 DAP followed by pendimethalin + hand weeding fb mulching and oxyfluorfen fb mulching. Higher benefit cost ratio of 1.7 was recorded with all weed control treatments except pendimethalin alone fb mulching and oxyfluorfen supplemented with one hand weeding fb mulchin

Not reported: Faizabad

3.4.1 Studies on time of application of imazethapyr and its ready mix combination with imazamox (Odyssey) against weeds in blackgram/greengram and its residual effect on the succeeding mustard crop.

Cooperating centres: Gwalior, Hisar, Ludhiana, Palampur, Anand, Faizabad, Pantnagar, Meerut, Bhubaneswar and Coimbatore

RVSKVV, Gwalior

Major weed flora in blackgram during kharif 2014 & 2015 was Cyperus rotundus, Echinochloa crusgalli, Dactyloctenium aegyptium, Acrachne racemosa, Commelina benghalensis, Digera arvensis, Rumex dentatus and Phyllanthus niruri. Hand weeding twice at 20 and 40 DAS proved effective in reducing weed density and dry weight of weeds followed by post and pre-emergence application of pre mix herbicides imazethapyr + imazemox at 70 & 80 g/ha and pendimethalin + imazethapyr (pre mix) at 1000 g/ha as PE, respectively. Pre mix herbicide was found more or less equally effective as two hand weeding treatment. Lowest weed population and weed dry weight was noted with two hand weedings at 20 and 40 DAS which was significantly higher to other weed control treatments. Whereas, pre mix herbicides imazethapyr + imazamox 70 & 80 g/ha as PoE followed by pendimethalin + imazethapyr  1000 g/ha as PE were found significantly effective than remaining other herbicide treatments. Pos- emergence application was found more effective than pre-emergence application in case of imazethapyr alone as well as pre mix herbicide. Alone application of pendiemthalin  1000 g/ha as PE and imazethapyr as PE was less effective than other treatments but significantly superior to weedy check. The highest weed control efficiency (95.4%) was recorded with two hand weeding at 20 and 40 DAS followed by imazethapyr + imazamox  80 g/ha as PoE (93.4%) and pendimethalin + imazethapyr 1000 g/ha as PE (90.0%). Phytotoxicity was not observed at 15 and 30 DAS stage of blackgram crop under any herbicidal treatments.

 On the basis of two year data it was concluded that in blackgram two hand weeding at 20 & 40 DAS gave maximum seed yield (924 kg/ha) followed by pre-mix herbicides i.e. imazethapyr + imazamox 80 g/ha as PoE (905 kg/ha) and pendimethalin + imazethapyr 1000 g/ha as PE (879 kg/ha). Whereas, net return & BC ratio were higher in pendimethalin + imazethapyr 1000 g/ha PE (3.32) followed by application of  imazethapyr + imazamox  80 g/ha PoE (3.11).

 Population of C. rotundus, A. arvensis and C. arvensis were not influenced significantly by any weed management practices on succeeding mustard crop at 60 DAS. In case of C. album all the treatments except imazethapyr 70 g/ha PE significantly affected the weed population as compared to weedy check. Lowest weed population was recorded in 2 HW followed by imazethapyr + imazamox 80 g/ha and pendimethalin + imazethapyr 1000 g/ha PE. Highest WCE was recorded in 2 HW (78.8%) followed by pendimethalin + imazethapyr  1000 g/ha PE (60.61%) and imazethapyr + imazamox 80 g/ha PoE (59.5%). On the basis of visual observation on 0-10 point scale none of the herbicide treatments applied on blackgram observed any phytotoxic effect on mustard crop. Maximum seed yield was recorded in treatment 2 HW (1.37 t/ha) followed by pendimethalin + imazethapyr 1000 g/ha (1.36 t/ha) and imazethapyr + imazamox 80 g/ha PoE (1.33 t/ha), but it could not reach the level of significance as compared to weedy check (1.1 t/ha).

CCSHAU, Hisar

Weed flora in greengram was dominated by Trianthema portulacastrum constituting 42.6% of total weed flora. Other weeds present in experimental field were D. aegyptium, E. crusgalli and Cyperus rotundus. All PPI and pre-emergence herbicide treatments proved effective against predominant weed T. portulacastrum. Post emergence application of imazethapyr and its combination with imazamox were very effective against grassy weed E. crusgalli but their efficacy against T. portulacastrum was very poor with only stunted plants. PPI and PRE use of imazethapyr  and its combination both at 70 and 80 g/ha provided good control of C. rotundus where as pendimethalin was not at all effective against this weed. Post emergence application of imazethapyr at 70 & 80 g/ha and imazethapyr + imazamox (RM) at 60-80 g/ha proved less effective in minimizing density and dry weight of weeds. Although post emergence application of both these herbicides caused suppression in Trianthema growth but pre-emergence treatments of pendimethalin in combination with imazethapyr, imazethaypr (PRE) and its pre-plant incorporation at 70 & 80 g/ha were very effective to minimize Trianthema population. None of PPI or PRE herbicide treatments caused suppression in crop growth since initial stages of crop growth. Seed yield was maximum (1003 kg/ha) in weed free treatment which was significantly higher than all treatments. Among herbicides, maximum seed yield (785 kg/ha) was obtained with PPI application of imazethapyr at 80 g/ha which was at par to its lower dose 70 g/ha (PPI), 80 g/ha (PRE), two hoeing employed at 20 & 40 DAS and pendimethalin 30 % EC+imazethapyr 2% (RM) at 1000 g/ha but higher than all post emergence treatments. Maximum B:C ratio of 2.49 was obtained with  PPI use of imazethapyr at 80 g/ha.

 All herbicide treatments except pendimethalin and its ready mixture with imazethapyr caused less or more residual toxicity on mustard. Visual toxicity on mustard was more in PPI treatments (90-95%) but less in PRE and POST applications of various herbicides. Mustard crop in these treatments showed significant variation in plant height, germination  percentage, number of leaves per plant as compared to untreated check, weed free and two hoeings. Maximum seed yield of mustard (2664 kg/ha) was obtained with weed free conditions imposed by hoeing and pulling in green gram which was at par with all treatments given in green gram except PPI application of imazethapyr at  both use rates and its  PRE and post emergence use at  80 g/ha.

 

PAU, Ludhiana

Cyperus rotunuds, Trianthema portulacastrum, Mollugo nudicalis, Acrachne racemosa and Digitaria ciliaris were the major weeds in blackgram crop. All herbicides, except pendimethalin as pre-emergence and imazethapyr as post-emergence, significantly reduced population of all weeds and weed biomass as compared to weedy check. Imazethapyr as pre-emergence was more effective against T. portulacastrum and as post-emergence against C. rotunuds; pendiemthalin did not control C. rotundus. All the weed control treatments recorded significantly higher black gram seed yield compared to weedy check and were at par with hand weeded control. The pre-emergence applications of imazethapyr 80 g, pre-mix of imazethapyr + imazmox 70-80 g and of imazethapyr + pendimethalin 1000g /ha recorded highest net returns and B: C ratio. All herbicides were safe to blackgram crop. The study indicated that pre- emergence application of imazethapyr alone or its pre-mix with pendimethalin/imazamox, depending on weed flora in the field, could be adopted for weed control in blackgram.

All the herbicides applied in blackgram did not show any residual effects on germination, growth and seed yield of succeeding Indian mustard indicating that all these herbicides could be adopted for weed control in blackgram- Indian mustard based cropping sequences.

AAU, Anand

The major monocot weeds observed in the greengram crop were Eragrostis major, Eleusine indica, Digitaria sanguinalis, Commelina benghalensis, Dactyloctenium aegyptium and Cyperus iria. Dicot weeds were Digera arvensis, Phyllanthus niruri, Euphorbia hirta, Oldenlandia umbellate, Amaranthus viridis, Boerhavia repanda and Vernonia cinerea. Significantly lowest density of monocot and total weeds were recorded at 40 DAS in pre-emergence application of imazethapyr + pendimethalin and remained at par with hoeing at 20 & 40 DAS. Whereas, lowest weed density and weed dry biomass of dicot weeds were recorded in post emergence application of imazethapyr + imazamox at 80 g/ha. Weed control efficiency varied between 80 to 93 % recorded at 40 DAS. Phytotoxic effect of imazethapyr and imazethapyr + imazamox (RM) was observed on greengram. Residual effect on succeeding mustard crop was evaluated and major dicot weeds observed in mustard crop were Chenopodium album, Chenopodium murale, Digera arvensis, Melilotus indica Oldenlandia umbellate Phyllanthus niruri and Boerhavia repanda. The monocot weeds were Dactyloctenium aegyptium, Commelina benghalensis, and Eleusine indica.

There was no carry over /residual phytotoxic effect observed on succeeding mustard crop. Seed and stalk yield of mustard showed non-significant effect of different weed management practices in greengram on succeeding mustard crop.

NDUAT, Faizabad

Blackgram crop was mainly infested with Eleusine indica, Echinochloa sp.,Panicum maxicum, Digitaria sanguinalis and Dactyloctenium aegyptium among grasses; Celosia argentia, Solanum nigrum, Trianthema monogyna, Cleome viscosa and Digera arvensis among broadleaved weeds (BLWs). However, Cyperus rotundus was the only sedge dominating among the total weed population.

Pre-mix combination of imazethapyr + imazamox at 70 and 80 g/ha (PE) and imazethapyr + pendimethalin 1000 g/ha applied as pre-emergence was found more effective in reducing density of weeds as compared to alone application of imazethapyr at 70 and 80 g/ha applied as pre and post emergence application. However, alone application of imazethapyr at 80 g/ha applied as post -emergence recorded less weed dry weight and WCE to the extent of 60.2%. Ready mix formulation of imazethapyr + pendimethalin 1000 g/ha was at par with imazethapyr + imazamox 80 g/ha and recorded significantly highest seed yield over other herbicide treatments. However, imazethapyr + imazemox at 80 g/ha applied as post-emergence, and pendimethalin 1000 g/ha (PE) also recorded fairly good yield of black gram. Uncontrolled growth of weeds (weedy check) resulted in 61.4 % reduction in seed yield of black gram over twice hoeing. The prominent weed species in mustard were P. minor, C. album, M. alba, F. parviflora, C. rotundus. There was no residual effect of herbicides applied in blackgram on mustard crop.

GBPUAT, Pantnagar

Prominent weed species in blackgram were E. colona (5.8%), E. indica (19.4%), D. aegyptium (9.3%) and D. sanguinalis (9.3%), among the grasses. C. argentia (12.9%), T. monogyna (13.6%), C. viscosa (2.5%), P. niruri (3.6%), and D. arvensis (5.0%) among broadleaved and C. rotundus (18.7%). Total dry matter accumulation of weeds was found minimum with twice hoeing at 20 & 40 DAS which was at par with ready mix application of Imazethapyr + pendimethalin as pre emergence at 1000 g/ha only. Highest weed control efficiency (100%) was achieved with twice hoeing at 20 and 40 DAS followed by ready mix application of Imazethapyr + pendimethalin as pre emergence at 1000 g/ha (97.9%). Ready mix application of Imazethapyr + pendimethalin at 1000 g/ha obtained maximum seed yield of black gram (1407 kg/ha) which was significantly higher to all other treatments except ready mix application of Imazethapyr +  imazamox as pre emergence at 80 g/ha and twice hoeing at 20 and 40 DAS.

TNAU, Coimbatore

In blackgram, Dinebera reteroflexa, Setaria verticilliata under grasses, Trianthema portulacastrum, Digera arvensis, Parthenium hysterophorus, Amaranthus viridis, Boerhaavia diffusa under broadleaved weeds and Cyperus rotundus and Cyperus iria under sedges were the predominant weeds. Imazethapyr + imazamox (RM) 80 g/ha recorded significantly lower weed density (11.2 /m²) at 40 DAS followed by hoeing twice on 20 and 40 DAS (13.2/m²) and it was comparable with EPOE imazethapyr + imazamox (RM) 70 g/ha Lower weed dry weight (7.0 g/m²) was recorded with EPOE imazethapyr + imazamox (RM) 80 g/ha followed by hoeing twice on 20 and 40 DAS (8.5 g/m²) and it was comparable with EPOE imazethapyr + imazamox (RM) 70 g/ha at 40 DAS. Higher weed control efficiency of more than 76.4% was recorded with EPOE imazethapyr + imazamox (RM) 80 g/ha. EPOE application of imazethapyr + imazamox (RM) 70 g/ha recorded next higher weed control efficiency of 72.3 %, which was followed by hoeing (20 and 40 DAS). Higher pod yield of 597 kg/ ha was recorded with PE imazethapyr + imazamox (RM) 80 g/ha. PE imazethapyr + imazamox (RM) 70 g/ha (550 kg/ha), EPOE imazethapyr + imazamox (RM) 80 g/ha (523 kg/ha), EPOE imazethapyr + imazamox (RM) 70 g/ha (520 kg/ha) and hoeing on 20 and 40 DAS (545 kg/ha) recorded comparable pod yield. PE imazethapyr + imazamox (RM) 80 g/ha received higher net returns (Rs.24,880 /ha) and B:C ratio (3.55) followed by PE imazethapyr + imazamox (RM)
70 g/ha (Rs.21,920).

Phytotoxicity symptoms were not observed in blackgram with application of pendimethalin, imazethapyr and imazamox or its combination during both pre and post emergence application. There was no reduction in the number of nodule formation in blackgram after application of imazethapyr, imazomox and pendimethalin in combination and/or alone.

Population of bacteria, diazotrophs and phosphobacteria were dropped slowly upto 7^th day in the treatments imposed with either PE or EPOE herbicides compared with hoeing and weedy check. However, it was increased from 15^th day onwards in the treatments imposed with either PE or EPOE herbicides. Imazethapyr + imazomox 80 g/ha showed maximum number of total bacteria (109.8 x 10⁶ cfu/g of soil), diazotrops (42.7×10⁴ cfu/g of soil) and phosphobacteria (34.57×10⁴ cfu/g of soil) at 30 days after herbicide application followed by imazethapyr + imazomox 70 g/ha. Similar trend was observed in the EPOE herbicides viz., imazethapyr + imazomox as well. In case of fungi and actinobacteria, there was no reduction in the population even after application of PE or EPOE herbicides compared with hoeing and weedy check. Imazethapyr in combination with imazamox either as PE or EPOE showed maximum fungi and actinomycetes population when compared to weedy check.

Cooperating centres: Hyderabad, Anand, Dharwad, Bengaluru, Hisar, Ludhiana, Coimbatore and Akola

AAU, Anand

Experiment on cotton was conducted to study the bio-efficacy of combination of herbicides against complex weed flora, their effects on growth and yield of cotton along with to study the phytotoxic effects on the crop.The major dicot weeds observed in the experimental field were Digera arvensis, Phyllanthus niruri, Oldenlandia umbellata and Boerhavia repanda. The monocot weeds were Dactyloctenium aegyptium, Digitaria sanguinalis, Commelina benghalensis, Eleusine indica, CyperusiriaandCyperusrotundus.

The highest plant height of cotton was recorded due topendimethalin fb directed spray of glyphosate at 45 DAS and remained at par with weedy check due to competition of crop with weeds. Weed density at 90 DAS were recorded lowest due to pre-emergence application of pendimethalin 1000 g/ha fb pyrithiobac-sodium 62.5 g/ha but remained at par with T_7, T₉ and T₃ treatments. Weed control efficiency was varies between 9 to 92 % compared to weedy check (table 3.5.1). Significantly higher seed cotton yield was recorded due to pre-emergence application of pendimethalin fb 2 HW carried out at 20 and 50 DAS (T₁) treatment which found at par with post-emergence application of pyrithiobac-sodium + quizalofop-p-ethyl fb directed spray of glyphosate 2000 g/ha at 60 DAS (T₇). Benefit cost ratio was the highest (2.57) in pre-emergence application of pendimethalin fb 2 hand weeding carried out at 20 and 50 DAS (T₁) followed by post-emergence application of pyrithiobac-sodium + quizalofop-p-ethyl fb directed spray of glyphosate at 60 DAS (2.47).

CCSHAU, Hisar

Experimental field was pre-dominantly infested with natural population of jungle rice (Echinochloa colona L.) and carpet weed (Trianthema portulacastrum.) to the extent of 71 & 29% at 90 DAS and 74 & 26 per cent at harvest, respectively.  Pendimethalin 1.0 kg/ha as pre-emergence provided effective control of Trianthema portulacastrum and Echinochloa colona and this effect remained consistent up to 90 DAS. Application of pendimethalin at 1.0 kg/ha supplemented with two hoeings  at 30 & 60 DAS, one hoeing and post emergence application of quizalofop-p-ethyl at 60 g/ha or propaquizafop-p-ethyl at 62.5 g/ha at 60 DAS caused significant reduction in density and dry weight of weeds as compared to weedy check up to harvest. Treatments involving use of parthiobac at 20 DAS were not effective as at 20 DAS, due to less moisture and higher temperature at that time.

Protected spray of glyphosate (0.5%) integrated with pendimethalin and paraquat (0.3%) with  parthiobac Na fb quizalofop-p-ethyl being at par with three mechanical weeding helped to reduce the population and dry weight of weeds at 90 DAS significantly over weedy check. Pendimethalin integrated with non-selective herbicides (paraquat or glyphosate) proved superior over application of pendimethalin fb quizalofop-p-ethyl or parthiobac Na fb quizalofop-p-ethyl against both type of weeds as shown by weed control efficiency. Treatments involving directed spray of paraquat caused 5-8 % toxicity to cotton crop. Weed control efficiency in all treatments except pendimethalin fb quizalofop-p-ethyl or parthiobac Na fb quizalofop-p-ethyl varied between 60.3- 83.2 % both at 90 DAS and at harvest. Number of bolls/plant were maximum (46) in weed free treatment which were significantly higher than all treatments except three mechanical weedings and parthiobac Na fb quizalofop-p-ethyl fb directed spray of  glyphosate. Weedy condition throughout crop growth period caused 47.2% reduction in seed cotton yield.

 

PAU, Ludhiana

Cyperus rotundus, Dactyloctenium aegyptium, Trianthema portulacastrum and Acrachneracemosa were major weeds in experimental plots. All treatments significantly reduced population and biomass of grass and broadleaf weeds compared to weedy check, however, glyphosate or hand weeding was required for significant reduction in sedges biomass. Sequential application of pendimethalin and pyrithiobac+quizalofop was more effective than pendimethalin fb pyrithiobac or pyrithiobac+quizalofop alone, with respect to control of grass weeds. Pendimethalin fb pyrithiobac + quizalofop recorded the highest seed cotton yield and B: C and it was followed immediately by pendimethalin integrated with glyphosate and pyrithiobac+quizalofop integrated with paraquat/glyphosate and 3 hand hoeings. All weed control treatments recorded significantly higher seed cotton yield than weedy check and prevented nutrient depletion by weeds. All the herbicides were safe to cotton.

UAS, Bengaluru

Major weed flora observed in the experimental plots were Cyperus rotundus, Digitaria marginata, Dactyloctenium aegyptium, Echinochloa crus-galli, Cynodon dactylon whereas, among broad leaf weeds, major weeds were Spilanthes acmella, Ageratum conyzoides, Alternanthera sessilis, Acanthospermum hispidum, Borreria articularis, Euphorbia hirta, Commelina benghalensis at 90 DAP and at harvest. At 90 DAS and harvest, the herbicides treatments were significantly superior compared to unweeded control with regards to weeds’ density and dry weight. Among herbicides the combination of pendimethalin 1000g/ha PRE fb 2 HW–20&50 DAS, pendimethalin 1000g/ha PRE fb pyrithiobac-sodium 62.5g/ha-20 DAS + quizalofop- p- ethyl 50g–20 DAS, pyrithiobac-sodium 62.5g/ha-20 DAS + quizalofop –p- ethyl 50g 20 DAS, fb directed spray of glyphosate 2000g/ha -60DAS, pyrithiobac-sodium 62.5g/ha-20 DAS + quizalofop- p- ethyl 50g 20 DAS, fb manual weeding-50DAS and Pyrithiobac –sodium 62.5g/ha-20 DAS + quizalofop –p- ethyl 50g 20 DAS fb directed spray of paraquat 600g/ha -60DAS recorded lower weed density and weed dry weight compared to other treatments indicating the necessity of combination of herbicides to manage complex weed flora in cotton.

Plot treated with herbicides recorded significantly higher cotton yield compared to all other treatments which were on par with the hand weeding treatment. Herbicides or herbicide mixtures were cheaper than hand weeding. Higher B:C ratio was obtained in ppendimethalin 1000g/ha PRE fb pyrithiobac-sodium 62.5g/ha-20 DAS + quizalofop- p- ethyl 50g–20 DAS (3.88), Pyrithiobac-sodium 62.5g/ha-20 DAS + quizalofop –p- ethyl 50g 20 DAS, fb directed spray of glyphosate 2000g/ha -60DAS (3.73) and it was only 2.44 in three mechanical weeding treatment.

PJTSAU, Hyderabad

No phytotoxicity was observed on cotton crop with application of any of the pre and post emergence herbicide. Glyphosate and paraquat were applied as directed spray.

The important monocotyledonous weeds observed in the experimental plots during crop growing season were Cyperus rotundus, Cynodon dactylon, Dactyloctenium aegyptium, Digera muricata, Digitarias anguinalis, Dinebra retroflexa, Panicum spp while common dicotyledonous weeds observed were Amaranthus polygamus, Commelina benghalensis, Parthenium hysterophorus and Trianthema portulacastrum. During crop growing season a steady decrease in weed dry matter was observed up to 90 DAS and there after slight increase in weed dry matter was observed. Significantly lower weed dry matter was observed with mechanical weeding thrice at 20,40 and 60 DAS at all the growth stages and was on a par with PE application of pendimethalin fb 2 HW, pendimethalin fb pyrithiobac-sodium + quizalofop- p- ethyl and pendimethalin fb glyphosate directed spray at 30 DAS, pendimethalin fb 2 HW and pyrithiobac-sodium + quizalofop- p- ethyl fb manual weeding at 60 DAS, pendimethalin fb 2 HW at 20 and 50 DAS at 90 DAS, however at 120 DAS in addition to T₁treatment early post emergence application of pyrithiobac -sodium + quizalofop –p- ethyl fb directed spray of paraquat and pyrithiobac-sodium + quizalofop –p- ethyl fb directed spray of glyphosate treatments showed on par weed dry matter with mechanical weeding thrice at 20,40 and 60 DAS treatment. Continued decrease in weed control efficiency was observed with advancement of crop growth stage. Similar trend was observed as that of weed dry matter. Plant height did not differ significantly at 90 and 120 DAS. However more plant height was observed with mechanical weeding thrice at 20, 40 and 60 DAS treatment at 30 and 60 DAS and was on par with PE application of pendimethalin fb 2 HW and Pendimethalin fb pyrithiobac-sodium application at 30 DAS. However at 60 DAS it was on par with early post emergence application of pyrithiobac-sodium + quizalofop- p- ethyl fb manual weeding at 50 DAS.

It is concluded that, either mechanical weeding thrice at 20, 40 and 60 DAS or pre emergence application of pendimethalin fb 2 HW at 20 and 50 DAS was found to be more economical to get higher kapass yield and net returns.

TNAU, Coimbatore

Dinebera reteroflexa and Setariaverticilliataunder grasses Trianthem aportulacastrum, Digeriaarvensis, Parthenium hysterophorus, Amaranthus viridis and Boerhaavia diffusaunder broad leaved weeds and Cyperus rotundusunder sedge were the predominant weed flora in the xperimental field.

At 90 DAS, EPOE pyrithiobac-sodium + quizalofop–p-ethyl (62.5+50 g/ha) at
20 DAS fb directed spray of glyphosate 2000 g/ha at 60 DAS recorded lower total weed density (5.1/m²) and total weed dry weigh (4.9 g/m²) followed by POE Pyrithiobac+quizalofop-p-ethyl (62.5 + 50) g/ha fb directed spray of paraquat 600 g/ha at 60 DAS (9.2/m²). At 90 DAS, higher weed control efficiency of 96 % was recorded in EPOE pyrithiobac-sodium + quizalofop –p-ethyl (62.5 + 50 g/ha) at 20 DAS fb directed spray of glyphosate 2000 g/ha at 60 DAS. At 90 DAS, higher plant height (92.3 cm) was recorded with PE pendimethalin 1000 g/ha at 3 DAS fb POE pyrithiobac-sodium + quizalofop –p-ethyl (62.5 + 50 g/ha) at 20 DAS. At 90 DAS, significantly higher DMP (3281 kg/ ha) of cotton was recorded in EPOE pyrithiobac-sodium + quizalofop –p-ethyl (62.5 + 50 g/ha) at 20 DAS fb directed spray of glyphosate 2000 g/ha at 60 DAS. The phytotoxicity symptoms were observed up to 21 days after herbicide spar due to directed spray of glyphosate 2000 /ha at 45 or 60 DAS.

PDKV, Akola

Cynodon dactylon, Cyperus rotundus, Commelina benghalensis, Ischaemum pilosum, Digitaria sanguinalis were dominant among monocot weeds and Digeraarvensis, Lagascamollis, Euphorbia geniculata, Tridex procumbense, Parthenium hysterophorus, Celosia argentea were dominant amongdicot weeds in the experimental field.

At 30 DAS, 3 HW at 20, 40, and 60 DAS recorded lowest weed count, weed dry matter and highest weed control efficiency but statistically found at par with pendimethalin PE 1.00 kg/ha fb 2 HW at 20 & 50 DAS, pendimethalin PE 1.00 kg/ha fb pyrithiobac sodium 0.062 kg /ha PoE 20 DAS and pendimethalin PE 1.00 kg/ha fb pyrithiobac sodium 0.062 kg/ha + quizalofop ethyl 0.050 kg/ha PoE 20 DAS (Tank mix). This might be due to better effect of pre emergence herbicide used alone or with combination of post emergence herbicide. While lowest weed index was noticed in pyrithiobac sodium 0.062 kg/ha + quizalofop ethyl 0.050 kg /ha PoE 20 DAS (Tank mix) fb directed spray of glyphosate 2.00 kg/ha 60 DAS (Table 3.5.2).This might be due to effective weed control in treated plot which resulted increase in yield. Herbicide combination in T₆, T₇ and T₈ showed some phytotoxicity symptoms on the lower leaves of cotton due to directed spray of non selective herbicide, no harmful effect on growth of plant were recorded. Number of monopodial branches was not affected by any treatment. The weedy check recorded lowest values of all the growth character. Weed control practices caused significant variation on seed cotton yield. The highest seed cotton yield (2.10 t/ha) was registered with 3 HW at 20, 40 and 60 DAS which was at par with pyrithiobac sodium 0.062 kg/ha + quizalofop ethyl 0.050 kg/ha PoE 20 DAS (Tank mix) fb HW 50 DAS, pyrithiobac sodium 0.062 kg/ha + quizalofop ethyl 0.050 kg/ha PoE 20 DAS (Tank mix) fb directed spray of paraquat 0.60 Kg/ha 60 DAS. Thus, the directed spray at 45 DAS was found most effective in controlling weeds and increasing seed cotton yield.