A field investigation was carried out during winter season of 2011-12 and 2012-13 at IARI Regional Station, Karnal (Haryana) to evaluate the effect of pre and post emergence herbicides on weeds, seed yield and seed quality of garden pea cv. Pusa Pragati. The twelve treatments viz. imazethapyr 50, 75 and 100g ha-1 (20DAS), pendimethalin 0.75 and 1.50kg ha-1  (pre-emergence), trifluralin 1.00 and 1.50kg ha-1  (PPI), ready mixture of imazethapyr and imazamox 50, 70 and 90g ha-1  (20DAS), hand weeding twice (20 and 45 DAS) and unweeded check were tested in randomized block design with three replications. The treatments hand weeding twice and imazethapyr @ 75g and 100g ha-1 recorded significantly higher pods per plant, seeds per pod, pod filling, 100 seed weight and seed yield than other herbicidal treatments and unweedy check. These treatments also recorded lower weed dry weight and higher weed control efficiency than other treatments. It may be inferred from the present investigation that in addition to hand weeding twice, post emergence herbicide imazethapyr @ 75g ha-1 (20DAS) can be used effectively as an alternative for controlling weeds and in obtaining optimum seed yield and quality in garden pea under Karnal (Haryana) conditions.


Effect of pre and post emergence herbicides on weeds and  seed yield of garden pea

<div>Background: Herbicides are used in agriculture to reduce the density of weeds and improve the crop yield. Pendimethalin 30% EC is widely used pre-emergent herbicide to control annual grasses and certain broad leaf weeds; is no longer effective against established weeds like Cyperus and Commelina benghalensis, Acalypha indica and Phyllanthus spp. that are dominant in groundnut crop. Combination of Pendimethalin 30% and Imazethapyr 2% EC is a broad-spectrum herbicide that controls most broadleaf weeds and some annual grasses. The current study aimed to improve the profitability of farmers by effectively and economically by controlling the targeted weeds. 
 
Methods: A field experiment was conducted at Zonal Agricultural and Horticultural Research Station (ZAHRS), Babbur Farm, Hiriyur, Karnataka during Kharif 2018, 2019 and 2020, to study the efficacy of pre and post-emergence herbicides for weed management in groundnut. The trial comprised of nine treatments involving two pre-emergence herbicides (Pendimethalin 38.7 CS 1.0 kg/ha PE and Pendimethalin 30 EC+Imazethapyr 2 EC 1.0 kg/ha PE (ready mix)) alone and in combinations with post-emergence herbicides (quizalofop-p-ethyl 50 g/ha at 15-20 DAS (PoE)), along with pre-emergence herbicides super imposed with hand weeding at 30 DAS and compared with two inter cultural operation at 15 and 30 DAS followed by manual weeding for intra rows and weedy check. 
 
Result: The experimental results revealed that, among the different herbicides treatments, the higher net return (Rs. 92,835/ha) and B:C ratio (2.70) were noticed in Pendimethalin 30 EC+Imazethapyr 2 EC 1.0 kg/ha PE (ready mix)+manual weeding at 30 DAS as compared to control plot (Rs. 2620/ha and 0.96, respectively) this has effectively controlled most of the weed flora present in the experimental field.</div>

​Efficacy of Pre and Post-emergence Herbicides for Weed Management in Groundnut

<div>Background: Greengram crop is grown round the year as a catch crop in different cropping systems of the uplands of the Krishna Zone of Andhra Pradesh. The practice of application of pre emergence herbicide like pendimethalin is very popular with the farmers for the control of weeds in the uplands, both in kharif and rabi seasons. Further spraying of a selective post emergence herbicide is also practiced by farmers. However, some of the weeds of kharif viz., Phyllanthus maderaspatensis and rabi viz., Chrozophora rottleri could not be controlled with these herbicides due to their late emergence or due to development of partial resistance to these herbicides. Certain new pre (PE) and post emergence (PoE) herbicides viz., pendimethalin 30% + imazethapyr 2%, acifluorfen sodium 16.5% + clodinafop propargyl 8%, fomesafen 11.1% + fluazifop -p-butyl 11.1%, are recommended in crops like soybean and groundnut.&nbsp; However, there is need to test these herbicides available in market for their suitability to control the weeds in greengram.&nbsp; 
 
Methods: A field experiment was carried out at Regional Agricultural Research Station, Lam, Guntur, Andhra Pradesh, with an objective to evaluate selected PE and PoE herbicide mixtures in greengram managing the major weeds of greengram grown in vertisols of Krishna Zone of Andhra Pradesh during Kharif and rabi seasons of 2018 under upland conditions. 
 
Result: Among the two PE herbicides tested on greengram, pendimethalin 30% + imazethapyr 2% @ 0.75 + 0.05 kg/ha was found to be more effective in reducing the weed density and dry matter compared with pendimethalin 30% @ 0.75 kg/ha. The PoE herbicide mixtures tested viz., fomesafen 11.1% + fluazifop -p-butyl 11.1% @111g/ha, propaquizafop 2.5% + imazethapyr 3.75% @ 50+75 g/ha&nbsp; &nbsp;were on par with imazethapyr 10% @ 50g/ha in controlling the weed population without having any adverse affect on the growth and yield of greengram during kharif and rabi.</div>

Evaluation of Pre and Post Emergence Herbicides in Greengram (Vigna radiata L.) during Kharif and Rabi Seasons in the Uplands of Krishna Zone of Andhra Pradesh

<div style="text-align:justify">A 6-row pre-emergence herbicide strip-application system was designed and developed at ICAR-CIAE, Bhopal as an attachment to inclined-plate planter to apply herbicide at the time of sowing in widely spaced crops to control weeds along the crop rows, often not possible in mechanical weeding. It consisted of a frame on which 6 flat fan spray nozzles were mounted by means of clamps, a single action piston pump with 9 l/min capacity, pressure regulator valve and pressure gauge and pressure pipes. The spacing between the spray nozzles, angle and height of spray nozzles can be varied by adjusting the clamps. The developed system has ability of strip as well as blanket application of herbicide. The same machine can be used as post-emergence herbicide/pesticide applicator after the removal of furrow openers and increasing the height of nozzles from the ground. The machine was tested and evaluated during Kharif season for soybean and pigeon pea crops. The field capacity of the developed system was found to be 0.4 ha/h. The operating cost of the pre-emergence herbicide applicator with inclined plate planter was worked out as Rs 1350/- per ha. It can save about 40-50% herbicide.</div>

<div style="text-align:justify">&nbsp;</div>

​Weed Control using Pre-emergence Herbicide Strip Application System Along with Sowing/Planting Devices

<div>Background: Blackgram (Phaseolus mungo L.), a major pulse crop of Andhra Pradesh grown in an area of 3.52 lakh ha with a production of 2.93 lakh tons during rabi season (Anonymous, 2019). One of the major characteristics for selection of blackgram varieties for rabi season under conditions of receding soil moisture in black soils is their early vigour and good weed smothering capability. Early varieties due to their early growth habit can cover the land and thus can smother weeds better than late maturing varieties. Further some variations are observed to be more tolerant to post emergence herbicide application. Hence, there is need to evaluate the promising blackgram varieties for their weed competitiveness and tolerance to pre and post emergence herbicidal application. 
 
Methods: A field experiment was carried out at Regional Agricultural Research Station, Lam, Guntur, Andhra Pradesh, with an objective to find out the competitive ability of blackgram varieties to smother weeds during rabi season of 2015-16 and 2016-17 under upland conditions. The experiment was laid out in split plot design with three replications. The treatments consisted of five methods of weed control as main plots, viz., pendimethalin 1.0 kg ha-1 PE, imazethapyr 50 g ha-1 PoE, pendimethalin 1.0 kg ha-1&nbsp;PE fb imazethapyr 50 g ha-1, PoE, manual weeding at 20 and 40 days after sowing (DAS) along with inter cultivation at 30 DAS and unweeded; four blackgram varieties, viz., GBG 1, PU 31, LBG 787, LBG 752, as sub treatments which were replicated thrice. 
 
Result: Weed dry matter recorded at 45 days was lower and weed control efficiency (WCE) was higher with pendimethalin 1.0 kg ha-1 PE fb imazethapyr 50 g ha-1 PoE and was on par with manual weeding with inter cultivation. All the varieties were comparable and equally effective in controlling weed dry matter. Yield of variety GBG 1 was higher due to higher yield attributes viz., no. of pods per plant and 100 seed weight. Among the weed control methods manual weeding treatment with inter cultivation recorded significantly higher yield followed by a combination of pendimethalin 1.0 kg ha-1 PE fb imazethapyr 50 g ha-1 PoE. Further, varieties GBG 1 and PU 31 performed better in manual weeding treatment with intercultivation and without any herbicide use.</div>

<div>Response of Blackgram (Phaseolus mungo L.) Varieties to Weed Competition and to Pre and Post Emergence Herbicide Application during Rabi</div>

<div>Background: Proper biodiversity conservation and strategies for sustainability in environmental and public health are essential measures for addressing the problems of water-related and zoonotic-caused pandemics. It is generally assumed that a resurgence in an epidemic disease is directly linked to negligence in environmental protection policies, but there are sparse scientific publications supporting the claim.&nbsp; 
 
Methods: To address this issue, we collected data on the global pre- and post- industrialization scenarios and subjected it to multivariate analyses to investigate the relationship between the lack of proper environmental protection and the emergence of new diseases.&nbsp; 
 
Result: Our investigations found a statistically significant association between the loss of wildlife habitat and the emergence of novel diseases. The study also revealed that wildlife-related zoonotic disorders caused more than 220 million deaths amongst global pandemics. More than 30 million deaths were attributed to waterborne diseases due to improper waste management and wastewater treatment. Thus, it is recommended that other environmental parameters (e.g., pollution phase) need to be investigated to fully understand the complex relationship between environmental protection and emergence of new zoonotic diseases.</div>

Environmental Protection Policy and the Emergence of New Diseases: A Global Empirical Analysis of the Pre- and Post-industrial Era

Background: Weeds are major constraints in chickpea production. This crop is highly susceptible to weed competition owing to slow initial growth thus weeds cause up to 75% yield loss.&nbsp;&nbsp; 
 
Methods: Treatments comprised of imazethapyr 50 g/ha as PE (pre emergence), imazethapyr 70 g/ha as PE, imazethapyr 50 g/ha as PoE (post emergence), imazethapyr 70g/ha as PoE, imazethapyr + imazamox ready mix (RM) 50 g/ha as PE, imazethapyr + imazamox (RM) 70 g/ha as PE, imazethapyr + imazamox (RM) 50 g/ha as PoE, imazethapyr + imazamox (RM)70 g/ha as PoE, pendimethalin 1 kg/ha PE, imazethapyr + pendimethalin (RM) 1 kg/ha PE, hoeing at 20 and 40 DAS and weedy check.&nbsp; 
 
Result: Application of imazethapyr + pendimethalin (RM) 1 kg/ha as pre emergence recorded maximum plant dry matter accumulation at 60, 90, 120 DAS and at maturity stage and also higher CGR at 60-90, 90-120 and120 DAS - maturity of crop. Application of imazethapyr + pendimethalin (RM) 1 kg/ha as pre emergence was most effective in producing higher seed yield (1749 kg/ha), weed control efficiency (87.28%), net return (` 77,136), reduced weed management index 5.15 and 3.90 at 30 and 60 DAS respectively.

Efficacy of Pre and Post Emergence Application of Imazethapyr and its Ready Mix Herbicides on Growth, Weed Dynamics and Productivity of Chickpea (Cicer arietinum L.)

<div style="text-align: justify;">The study was conducted at Agricultural Research Station, Mandor, Jodhpur during 2016-17 (rabi). The experiment was laid out in randomized block design (RBD) with 16 treatments and replicated thrice. The treatments were two doses of each herbicides i.e. pendimethalin (0.40 and 0.60 kg a.i./ha), oxyfluorfen (100 and 200 g a.i./ha) and imazethapyr (40 and 60 g a.i./ha) with their combinations as pre and post-emergence including weedy check and weed free. Among the herbicidal treatments, sequential application of pre and post-emergence herbicides i.e. pendimethalin @ 0.60 kg a.i./ha (PE) + imazethapyr @ 60 g a.i./ha at 20 DAS (W12) recorded significantly higher seed yield with higher weed control efficiency and weed index and established its superiority over other weed management treatments. However, it remained at par with pre and post-emergence herbicides i.e. pendimethalin @ 0.60 kg a.i./ha (PE) + imazethapyr @ 40 g a.i./ha at 20 DAS (W11) at all growth stages of crop. Although, weed free recorded higher seed yield and showed significant superiority over rest of the weed management treatments, but it was statistically at par with W12 and W11.&nbsp;</div>

<div style="text-align: justify;">Efficacy of pre and post-emergence herbicides on weed control in chickpea&nbsp;(Cicer arietinum L.)</div>

Background: Uncontrolled weed growth reported to reduce rice yields by 33 to 45%, while manual weeding is labor-intensive, time-consuming and costly. Pre-emergence herbicides prevent weed establishment and post-emergence herbicides target established weeds, offering effective and less costly weed control. However, an integrated approach to weed management is crucial to ensure long-term agricultural sustainability and minimize environmental impacts and weed resistance development. 
&nbsp; 
Methods: An experiment was conducted at Post Graduate Research farm, M.S. Swaminathan School of Agriculture, Centurion University, Paralakhemundi, Odisha during the kharif season of 2023 in randomized block design with fourteen treatments viz., Pyrazosulfuron ethyl 10% WP @ 200 g/ha at 1-3 DAT(T1), Bispyribac sodium 10%SC @ 250 ml/ha at 25 DAT(T2), Penoxsulam 21.7%SC @ 166 ml/ha at 25 DAT (T3), Metsulfuron methyl 10% + Chlorimuron ethyl 10%WP @ 4 g/ha at 25 DAT (T4), Florpyrauxifen-benzyl 1.31% + Penoxsulam 2.1% @2027ml/ha at 25 DAT (T5), Pyrazosulfuron followed by Bispyribac sodium at 25 DAT (T6), Pyrazosulfuron followed by Penoxsulam at 25 DAT (T7), Pyrazosulfuron followed by Florpyrauxifen-benzyl + Penoxsulam 25 DAT (T8), Pyrazosulfuron followed by Metsulfuron methyl 10%+ Chlorimuron ethyl 10% 25 DAT (T9), Triafamone20%+ Ethoxysulfuron 10% WG@ 225 g/ha at 20 DAT (T10), Pyriftalid 31.0% + Bensulfuron methyl15.7% @375ml/ha 20 DAT (T11), Pyrazosulfuron followed by one hand weeding at 25 DAT (T12), Hand weeding twice at 25 and 45 DAT (T13) and Weedy check (T14) which were replicated thrice. 
&nbsp; 
Result: At 30 and 60 DAT, the total weed density and dry weight was significantly low in hand weeding twice at 25 and 45 DAT over all other treatments. At 30 DAT, the weed control efficiency was higher in the treatment Hand weeding twice at 25 and 45 DAT (T13) followed by T8&nbsp;and T12&nbsp;where the efficiency was more than 90%. At 30 DAT, the dry matter was significantly higher with T13&nbsp;and T8 over all other treatments.The grain yield observed with T13&nbsp;was on par with that of T8&nbsp;and T10&nbsp;and significantly superior over all other treatments. For getting higher yield and net returns in transplanted rice, application of T8, T10, or T13&nbsp;is recommended for transplanted rice during kharif season. This paper is aligned with UN SDG 14.

Pre and Post Emergence Herbicides Influence on Productivity of Transplanted Rice

Blackgram is one of the most important pulse crop cultivated in India. It is a rich source of protein, carbohydrate, fat, amino acids and vitamins as human food and also serves as highly nutritive livestock feed. Despite of having multiple benefits poor agronomic and management practices viz., use of poor-quality seeds, poor crop establishment, moisture stress at critical stages of crop growth, low fertilizer input and inadequate weed management are responsible for low productivity of blackgram. Out of these poor weed management is one of the most important factors that needs focus of ongoing research and researchers to cut down the yield losses in blackgram. Weeds are the major biological constraint that leads to decline in crop yields. If not controlled in the early crop growth stage, they can reduce the yield up to 27-78 per cent. There are numerous weed control methods like cultural, physical/mechanical, biological and chemical available by which we can successfully controlled weeds. Out of these, the chemical weed control method is the most efficient way to control them by sequential application of pre-emergence and post-emergence herbicides in summer sown blackgram. Due to the availability of several herbicide molecules (chemical) in the market, its easy and very effective way to control weeds when applied in the right amount at the right time. Several weed scientists also suggest that allelopathy can be used to control and may offer substitute to chemical weed control or may lead to reduction in dose of herbicides applied. So, it can also be said that the integrated weed management method is the key to sustainable crop production worldwide and will continue to be the main pillar for weed control in blackgram. The present review paper is focussed on to get a clear understanding of the chemical method of weed control in black gram and has been undertaken to study the efficacy of pre-emergence application of herbicides followed by post-emergence application of herbicides in summer blackgram. 
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Weed Management in Summer Sown Blackgram (Vigna mungo L.) through Sequential Application of Pre and Post-emergence Herbicides: A Review