Abundance

Distribution

Occurrence

Rice

Sacciolepis interrupta

A survey was conducted in major rice tracts of Kerala i.e. Kole, Kuttanad and Palakkad during 2018 and 2019 to assess the distribution and occurrence of Sacciolepis interrupta. In Palakkad and Kole tract the highest density, frequency, abundance, relative density, relative frequency, and summed dominance ratio of Sacciolepis was recorded whereas, in Kuttanad tract it was Echinochloa crusgalli followed by Sacciolepis. Weed vegetation analysis indices were lowest in Palakkad compared to Kole and Kuttanad tract showing a high degree of domination of one species in Palakkad and larger diversity of weed species in other two tracts. The cluster analysis classified Sacciolepis types into 6 groups at 66.67% similarity level, and using principal component analysis these morphotypes were clustered into 3 groups A, B and C based on morphological characters. Association between Sacciolepis types and soil nutrient parameters indicated that Group A was abundant in less fertile saturated soils whereas group B and C were dominant in nutrient rich submerged soils of Kole and Kuttanad. The study concludes that Sacciolepis interrupta is a serious weed problem in direct seeded rice of Palakkad tract and is fast attaining the status of a dominant weed in other rice tracts also, thereby becoming a major menace in rice fields of Kerala.

Herbicides

Penoxulam + butachlor

Ready-mix

Transplanted rice

Weeds 

A field experiment was conducted to evaluate the efficacy of penoxsulam 0.97%w/w (1.0%w/v) + butachlor 38.8% w/w (40% w/v) 41% SE applied as pre-emergence( 0-7DAT) spray in standing water against complex weed flora in transplanted rice at CCS HAU Regional Research Station, Karnal during rainy (Kharif) seasons of 2015 and 2016. The crop was infested mainly with Echinochloa crus-galli (~15%), Ammannia baccifera (~70%), and Cyperus difformis, Cyperus rotundus and other sedges (~15 %). Penoxsulam + butachlor 41% SE at 820 g/ha being as good as weed free check provided almost complete control (98.1-98.5% WCE) of complex weed flora during both the years, and it was better than penoxsulam 22.5 g/ha (87-88%), butachlor 1500 g/ha (90%) and pretilachlor 1000 g/ha (91%). Penoxsulam + butachlor 820 g/ha resulted into the highest number of effective tillers and grain yield (5.43 t/ha in 2015 and 6.06 t/ha in 2016). It was superior to its lower doses (615 and 718 g/ha) and penoxsulam 22.5 g/ha during both the years, and butachlor 1500 g/ha during 2016. There was no crop phyto-toxicity of penoxsulam + butachlor 41% SE at 820 g/ha (X) and 1640 g/ha (2X). Weeds allowed to grow throughout the crop season reduced the grain yield to the extent of 27.3 and 32.9% during 2015 and 2016, respectively.

Kharif

Method

Rice

Weed

Yield

The field experiment was conducted at Agronomy Department Farm, College of Agriculture, Dapoli, during Kharif (rainy) seasons 2016 and 2017 to study the effect of established by different methods of rice establishment on weeds. The field experiment was laid out in a strip plot design comprising of twenty five treatment combinations replicated thrice. The horizontal strips comprised five rice establishment methods, viz. sowing of dry seeds by drum seeder at onset of monsoon, sowing of sprouted seeds (Rahu) by drum seeder in puddled field, broadcasting of sprouted seeds (Rahu) in puddled field, system of rice intensification (SRI) method and conventional transplanting. The vertical strips consisted five weed management practices, viz. need based two hand weedings at 20/30 and 40/60 DAS/DAT, pre-emergence application of oxadiargyl 80 WP 100 g/ha + 1 hand weeding at 20/30 DAS/DAT, pre-emergence application of oxadiargyl 80 WP 100 g/ha + 1 hand weeding at 40/60 DAS/DAT, pre-emergence application of oxadiargyl 80 WP 100 g/ha + post-emergence application of Almix 20 WP 4 g/ha and unweeded control. SRI method with two hand weedings carried out at 20 and 40 DAT recorded highest grain and straw yield of rice and lowest weed density and dry weight of weeds as compared to remaining treatment combinations during both the seasons.

Climate resilient rice

Invasive alien weeds

Integrated weed management

The present investigation was conducted to evolve a suitable weed management practice for invasive alien weeds in transplanted rice at Annamalai University Experimental Farm, Annamalainagar, during samba seasons of consecutive years (2015 and 2016). The experiments were laid out in a split plot design with the conventional rice and submergence tolerant rice varieties compared in main plot. Weed management practices, viz. unweeded control, twice hand weeding (at 30 and 45 DAT), butachlor 1.5 kg/ha, bensulfuron-methyl 0.06 + pretilachlor 0.6 kg/ha and oxadiargyl 0.07 kg/ha were compared in sub treatments. The results indicated that submergence tolerance as a biological or genetic trait in crops helped suppressing invasive alien weeds like Leptochloa chinensis and Marsilea quadrifolia, offering biotic resistance to invasion by alien weeds and when integrated with weed control measures. Hence, weed control in submergence tolerant rice with the application of bensulfuron-methyl 0.06 + pretilachlor 0.6 kg/ha could be suggested as an efficient weed control programme for monsoon transplanted rice crop.

Cropping Sequence

Diversification

Rice-wheat

Weed Density

Weed Dry Weight

Economic Yield

Effects of ten diversified rice based cropping sequences on weed dynamics were evaluated at Banaras Hindu University, Varanasi (Uttar Pradesh) in different season during 2016-17 and 2017-18. The results revealed that density of Cyperus spp., Cynodon dactylon and Digitaria sanguinalis was significantly lowest in rice-potato-greengram sequence but it remained at par with rice-berseem-cowpea fodder, rice-cabbage-cowpea fodder and rice-potato-cowpea fodder during second year in rainy season. Dry weight of Digitaria sanguinalis was significantly lowest under rice-potato-greengram sequence. During winter season, significantly lower density and dry weight of Medicago denticulata, Chenopodium album as well as total weeds were recorded in mustard (rice-mustard-cowpea fodder), though it was found similar with mustard (rice-mustard-sudan grass fodder), potato (rice-potato-greengram and rice-potato-cowpea fodder) and wheat (rice-wheat, rice-wheat-greengram and rice-wheat-cowpea fodder). While, density of Cynodon dactylon was markedly lower in wheat (rice-wheat) it was on a par with mustard (rice-mustard-sudan grass fodder), potato (rice-potato-green gram, rice-potato-cowpea fodder) and wheat (rice-wheat-greengram, rice-wheat-cowpea fodder). During summer season, cowpea grown in rice-cabbage-cowpea fodder recorded significantly lower density as well as dry weight of Cyperus rotundus, Cynodon dactylon as well as total weeds. Grain yield of rice was significantly higher in rice-berseem-cowpea fodder. During winter season, berseem in rice-berseem-cowpea fodder sequence out yielded all the other crops. However, in summer, sudan grass in rice-mustard-sudan grass fodder produced the highest green fodder yield.

Bio-efficacy

Crop resistance index

Herbicide efficiency index

Phytotoxicity

Readi-mix herbicide

Weed control index

A field experiment was conducted during 2015-16 and 2016-17 at Rajasthan College of Agriculture, Udaipur, India to evaluate the bio-efficacy of readi-mix herbicides in late sown wheat. The experiment consisting of fifteen treatments was laid out in randomized block design with four replications. The results revealed that Readi-mix application of sulfosulfuron + metsulfuron (32 g/ha)) and mesosulfuron + iodosulfuron (14.4 g/ha) gave higher weed control index (95.36, 94.72%), lower weed index (2.00, 2.75%) and weed persistence index (0.349, 0.351) whereas, higher index value of crop resistance index (CRI), weed management index (WMI) and herbicide efficiency index (HEI) (28.61, 0.38 and 5.50). Both of these treatments recorded 34.3 and 33.3 per cent grain yield enhancement along with 49.0% and 47.7% higher net returns over the unweeded control with the highest benefit-cost ratio (2.34 and 2.32). Results from contract analysis indicated significant (p < 0.0001) interaction of year x treatments and response of Readi-mix v/s single/sequential herbicide application on grain yield, weed density and dry matter. The joint effect of parameters on grain yield was significant with high magnitude (RGY.Weed density total, Weed dry weight total, Total N, P and K uptake = 0.98; p < 0.0001). Additionally, the regression model for grain yield on total weed density (R2 = 0.84), weed dry weight (R2=0.79), total N uptake (R2=0.98), P uptake (R2=0.93) and K uptake (R2 = 0.97) demonstrated significant dependence. Moreover, no symptoms of phytotoxicity were seen in any of the treatment in the crop at 21 days after herbicide application.

Chlorophyll content index

Chlorophyll fluorescence

Hormesis

Wheat

A field experiment was conducted in Rabi 2016-17 and 2017-18 to assess the effect of 2,4-D sodium salt at 5, 10, 20, 40 and 50 g/ha along with the recommended dose of 500 g/ha on wheat and associated dicotyledonous weeds (Medicago denticulata and Rumex dentatus). Foliar applied 2,4-D in the range of 5-20 g/ha increased the chlorophyll content index (CCI) and chlorophyll fluorescence (Fv/Fm) values in wheat as compared to control, demonstrating biphasic dose response (hormetic effect) of this auxinic herbicide. But the stimulatory effect of 2,4-D at low doses was observed only upto flag leaf stage of crop. Grain and straw yield of wheat was not boosted significantly by the low doses of 2,4-D, indicating that growth stimulation by sub-toxic doses of 2,4-D was not sustained over time. The foliar application of 2,4-D at ultra-low doses of 5-50 g/ha did not exert hormetic effect in R. dentatus and M. denticulata as application of different doses of 2,4-D led to a reduction in seed production potential of these weeds.

Grain yield

Herbicides

Maize

Post-emergence

Tembotrione

Weed flora

Weeds

A field experiment was conducted at Advanced centre for rainfed agriculture, Rakh Dhiansar of Sher-e- Kashmir University of Agricultural Sciences and Technology of Jammu during the crop growing seasons of 2016 and 2017 to identify the best herbicide option for weed management in maize (Zea mayz L.). Fifteen treatments were tested in randomised block design replicated thrice.  The post-emergence treatment (PoE) of tembotrione 100 g/ha + atrazine tank mix formulation 750 g/ha at 15-20 days after sowing (DAS) has recorded highest weed control efficiency (93.22 and 93.71% during 2016 and 2017, respectively) followed by tembotrione 100 g/ha + atrazine 500 g/ha at 15-20 days after sowing (DAS) and sequential application of atrazine 1000 g/ha 0-3 DAS fb tembotrione 100 g/ha 15-20 DAS. Higher maize grain yield was recorded (3.64 t/ha and 3.74     t/ha during 2016 and 2017, respectively) with weed free which was statically at par with tembotrione 100 g/ha + atrazine 500 g/ha at 15-20 DAS, tembotrione 100 g/ha + atrazine 750 g/ha at 15-20 DAS, tembotrione 100 g/ha + halosulfuron 67.5 g/ha at 15-20 DAS, tembotrione 100 g/ha+ halosulfuron 52.5 g/ha at 15-20 DAS, atrazine 1000 g/ha 0-3 DAS  fb metribuzin 250 g/ha 15-20 DAS, atrazine 1000 g/ha 0-3 DAS  fb tembotrione 100 g/ha 15-20. B: C ratio (3.11 and 3.12 in 2016 and 2017 respectively) was high with PoE application of tembotrione 100 g/ha + atrazine 500 g/ha.

Cotton, Economics, Glufosinate ammonium, Phytotoxicity, Soil micro-flora, Yield

A field experiment was conducted at Bidhan Chandra Krishi Viswavidyalaya, Mohanpur, West Bengal, India in Kharif season of 2016 and 2017 to evaluate the phytotoxicity of glufosinate ammonium 13.5% SL (15% w/v) on cotton and soil micro-flora and their consequent effects on crop growth, yield and economics. Findings depicted that there were no phytotoxic symptoms on cotton and there was better recovery of soil micro-flora population with the application of glufosinate ammonium 13.5% SL (15% w/v) 450 g/ha, resulting in maximum growth, yield and economic profitability of cotton. However, prominent toxic effects of glufosinate ammonium 13.5% SL (15% w/v) on the crop and soil micro-flora were recorded at higher doses of 900 g/ha and 1800       g/ha, which significantly reduced cotton growth, yield and economic viability.

Farm yard manure

Fennel

Greengram

Mulch

Vermicompost

Weed management

A field trial was conducted during two consecutive Rabi season of 2016-17 and 2017-18 on loamy sand soil at AICRP-Weed Management, B.A. College of Agriculture, Anand Agricultural University, Anand (Gujarat) to study the effect of integrated weed management in fennel production system and its residual effect on succeeding summer greengram. Significantly, lowest and highest weeds density at harvest was recorded with farm yard manure (FYM) 20 t/ha and vermicompost 8.0 t/ha, respectively. However, highest fennel seed yield (2.09     t/ha) was recorded with vermicompost 8.0 t/ha application. Significantly higher plant height, number of umbels/plant and seed yield was recorded with paddy straw mulch 10 t/ha fb hand weeding (HW) at 30 and 60 days after transplanting (DATP) and it was at par with paddy straw mulch 5 t/ha fb HW at 30 and 60 DATP and twice inter cultivation (IC) + HW at 30 and 60 DATP fb earthing-up at 75 DATP. Higher fennel equivalent yield (2.43 t/ha) and gross return ( 243000/ha) was recorded with application of vermicompost 8.0 t/ha, while highest net return ( 138220/ha) and benefit cost ratio (2.56) was recorded with application of FYM. Paddy straw mulch 10 t/ha fb HW at 30 and 60 DATP recorded higher fennel equivalent yield (3.24 t/ha), gross returns ( 219816/ha), net returns ( 241976/ha) and benefit cost ratio (3.11). Application of FYM and vermicompost was found equally effective while mulching treatments recorded higher seed yield of succeeding greengram.

Accelerated ageing

Burial depth

Germination

Light

Temperature

Salinity

Golden crownbeard (Verbesina encelioides), which is abundant along roadsides in Northern India, has started to invade field borders in the South West of Punjab. This study was conducted to find the effect of environmental factors and accelerated ageing on germination of this weed. It germinated over a wide range of temperatures (15/5-35/25°C) with optimum germination at 25/15°C. Light was not a pre-requisite for germination. Germination was completely inhibited at -0.6 MPa. The seeds germinated at 160 mM sodium chloride (13.3%), but no germination was observed at 180 mM NaCl. Germination of seeds was very low at pH less than 5 or more than 8. Germination was 95% when seeds were placed on the soil surface. No emergence was observed when seeds were buried to 6 cm or greater depth. Accelerated ageing of seeds for 20 or more days completely inhibited germination. Results indicate that this weed can emerge in multiple germination flushes. It also has the ability to invade drought affected areas, and can grow in soils that are moderately saline, slightly acidic, or alkaline. However, this weed is not expected to buildup persistent soil seed banks due to rapid loss of viability (time to 50% persistence = 4.11 days) under accelerated ageing.

Brown sarson

Importance value index

Weed density

Weed diversity Weed frequency

A study on weed flora was conducted to evaluate the weed species distribution across different brown mustard (Brassica rapa var. brown sarson) growing areas of Kashmir valley during Rabi (2016-17 and 2017-18). The occurrence of weed species was assessed on the basis of different phyto-sociological attributes, viz. weed species density, relative density, relative frequency and importance value index. These were computed from the data collected during the month of March. In all twenty weed species were identified of which sixteen were broad-leaved. The crop was highly infested with the weed species of Poaceae family with the dominance of Poa annua (IVI of 84.9, 50.6 and 44.1 in Pulwama, Anantnag and Kulgam, respectively). Among the broad-leaved weeds, Veronica persica was the most dominant species found in Budgam with the abundance value of 17.25 and IVI of 34.5. Budgam had the highest weed species distribution with Simpson’s diversity index (D) of 0.120123.

Cut tuber

Herbicides

Sprout-eye

Weeds

Whole tuber

Weed management and planting methods in potato cultivation affect the tuber yield and quality significantly, and hence, requires proper management. Therefore, to explore the possibilities of developing a pre-emergence (PE) herbicide application system for potato planter specially for cut seed pieces (tubers) a study was conducted at ICAR-Directorate of Weed Research (DWR) during Rabi season of 2017-18 and 2018-19. The study includes different sprout-eye orientation of the potato tubers along with different weed management practices. The application of metribuzin at 0.75 kg/ha as PE effectively controlled the weeds and obtained a weed density of 2.43 and 2.04 weeds/m2 and weed dry biomass of 1.35 and 1.64 g/m2 respectively at 25 and 55 DAP. By application of the metribuzin as PE and paraquat as early-post emergence (PoE), the tuber yield was increased from 9-16.5%. The sprout-eye orientation has significant effect on tuber yield. The tuber yield was reduced by 28.3% and 16.7% respectively, in 2700 sprout-eye orientation and random dropping over sprout-eye orientation of 90±300. The highest tuber yield of 28.4 t/ha was obtained in planting of whole tuber having the size of 40 to 50 g per tuber. The application of metribuzin as PE effectively controlled the weeds, thus a PE applicator system can be developed along with the potato planter.

Allelopathy, Aqueous extract, Phalaris minor, Sorghum, Sunflower

A field experiment was conducted in G.B Pant University of Agriculture and Technology, Pantnagar during Rabi season of 2018-19 to evaluate the bioefficacy of aqueous extracts of sorghum and sunflower on Phalaris minor, as well as their effects on yield and yield attributing characters of wheat. The experiment was carried out with eight treatments, each with three replications in randomized block design (RBD). Treatment with pre fb early post-emergence application of sunflower extract recorded highest weed control efficiency and yield among the treatments having aqueous extract application. Maximum WCE was recorded in pre fb early post-emergence application sunflower followed by pre fb early post-emergence application sorghum in every stages of observation. The grain yield of weedy, pre- fb early post-emergence application sorghum, pre- fb early post-emergence application sunflower, weed free plot was recorded as 2.33, 4.13, 4.38, 5.14t/ha, respectively.

Brown manuring

Crotalaria juncea

Maize

Sesbania bispinosa

Weed

Weeds result in yield losses up to 40% in maize in India. Brown manuring can suppress weeds better and provide ecosystem services. It has been hardly studied in crops other than rice. It offers potential for adoption in maize, but needs to be optimized because maize differs from rice in growth habit and architecture and has no tillering capacity. Therefore, this study was undertaken to optimize brown manuring option(s) that involved two brown manure species, their mixture and seed rates, and the times of application of 2,4-D. Results revealed that all brown manuring treatments suppressed noxious weed Cyperus rotundus better than the recommended tank-mixture of atrazine + pendimethalin. Among them, a brown manuring option that involved 1:1 mixture of Sesbania bispinosa (12.5 kg seed/ha) + Crotalaria juncea (12.5 kg seed/ha) + 2,4-D 0.5 kg/ha applied at 35 DAS resulted in highest reduction in weed density (~91%). Another brown manuring option, i.e., Sesbania  + Crotalaria (12.5+12.5 kg/ha) mixture and 2,4-D 0.5 kg/ha applied at 25 DAS gave similar weed suppression, and was superior to it on maize grain yield (~13.4%), gross return (~15.7%) and gross benefit:cost (~15.6%). This brown manuring would be a profitable weed management practice in maize. It may lead to sequester C and N in soil and provide ecosystem services as well.

Alternanthera ficoidea, Temperature and salinity stress, Germination indices

Alternanthera ficoidea (Sanguinarea) (Amaranthaceae) is an exotic weed that has widely spread in most of the terrestrial habitats including saline soils under different climatic conditions. Seed germination is an important stage in seedling establishment and maintaining health and vigour of every plant. Seed germination studies were carried out under temperature and salinity stress. Weed seeds showed adaptation to temperature as well as salinity stress in laboratory as well as field conditions. Such type of adaptation may be one of the reasons for rapid spread and establishment of this weed.

Alternaria alternata

Degradation

Herbicide

Pyrazosulfuron-ethyl

Herbicides are now used throughout the globe and a majority of applied chemicals enter into the soil to form short or long-term residues, resulting in toxicity to sensitive crops and adverse effects on human and other life forms. Therefore, present work was undertaken to isolate and identify pyrazosulfuron-ethyl degrading fungi from soil of rice field. Alternaria alternata was isolated and identified from rhizosphere soil of rice field, as a potent pyrazosulfuron-ethyl degrading fungus and its degradation potential was evaluated under controlled conditions. In the soil pyrazosulfuron-ethyl was efficiently degraded by A. alternata. Degradation of pyrazosulfuron-ethyl by A. alternata was achieved by the cleavage of sulfonylurea bridge and hydrolysis. A. alternata used in the study can effectively be used for the enhanced degradation of pyrazosulfuron-ethyl in agricultural soil or mixed with other microbial consortia for rapid degradation with half life of 7.9 days.