The field study was undertaken during rainy season of 2012 and 2013 to evaluate the rice cultivars and weed management effects on weeds growth and yield of direct-seeded rice (DSR) cultivars. The associated weed flora include Echinochloa colona, Echinocloa crus-galli, Cynodon dactylon as grasses; Cyperus rotundus, Cyperus iria as sedges; Caesulia auxillaries and Eclipta alba as broad-leaved weeds. Bispyribac-sodium  + azimsulfuron (25 + 35 g/ha) + 0.25% NIS as post-emergence at 15-20 DAS was found to be most effective in minimizing weed density, biomass and in enhancing the weed control efficiency 40.9% and 38.0% during 2012 and 2013 at 60 DAS, respectively. The maximum rice grain, straw and biological yield was found with application of bispyribac + azimsulfuron (25 g + 35 g/ha) + 0.25% NIS as post-emergence at 15-20 DAS and was significantly superior over rest of the treatments during both the years of study. 

A field experiment was conducted during Kharif 2015 and Summer 2016, at Agricultural Research Station, Dhadesugur, University of Agricultural Sciences, Raichur, Karnataka, India, to study the effect of different herbicides for control of weeds in irrigated dry-seeded rice. The dominant weeds in fields were Echinochloa sp. Panicum repens, Cynodon dactylon, Bracharia mutica, Digitarias anguinalis and Leptochloa chinensis among grasses, Eclipta alba,Commelina communis and Ludwigia parviflora as among broad-leaf weeds and Cyperus sp. as sedge. Among herbicidal treatments, post-emergece application of BAS 9548 H (penoxsulam 10 g/l + bentazone 360 g/l SC) 3000 ml/ha recorded significantly higher rice grain yield followed by the application of BAS 9548 (penoxsulam 10 g/l + bentazone 360 g/l SC) 2500 ml/ha and twice hand weeding at 15 and 30 days after sowing (DAS). The maximum B:C ratio was observed in plots treated with BAS 9548 H (penoxsulam 10 g/l + bentazone 360 g/l SC) and twice hand weeded check.

The experiment was conducted on irrigation levels and integrated weed management practices during 2013 and 2014 at College of Agriculture, Hyderabad. Results revealed that higher grain yield was recorded with scheduling of irrigations at IW/CPE ratio of 2.0 (2.55 and 2.42 t/ha) due to accumulation of higher chlorophyll content and dry matter production of crop. Net returns (` 20656 and 18347/ha) and benefit cost ratio (1.7 and 1.6) was also higher with the same irrigation level. Scheduling of irrigations at IW/CPE ratio of 1.5 was the next best treatment in aerobic rice. Out of weed management practices tested, application of pendimethalin/butachlor as pre-emergence fb chlorimuron-ethyl + metsulfuron-methyl  post-emergence fb MW + HW at 45 DAS recorded lower weed population, weed dry matter and higher in weed control efficiency, which resulted higher chlorophyll and dry matter accumulation in crop and finally produced higher grain yield in pendimethalin 1.0 kg/ha as PE fb MSM + CME 4.0 g/ha at 25 DAS + MW fb HW at 45 DAS (2.15 and 2.05 t/ha) and butachlor 1.0 kg/ha as PE fb MSM + CME 4.0 g/ha at 25 DAS + MW fb HW at 45 DAS (2.08 and 1.98 t/ha). The same treatments recorded higher net returns and benefit cost ratio in pendimethalin 1.0 kg/ha as PE fb MSM + CME 4.0 g/ha at 25 DAS + MW fb HW at 45 DAS (1.6 and 1.5) and butachlor 1.0 kg/ha as PE fb MSM + CME 4.0 g/ha at 25 DAS + MW fb HW at 45 DAS  (1.6 and 1.5). Over the pooled years, significant interaction effect of irrigation scheduling at IW/CPE ratio of 2.0 along with application of pendimethalin/butachlor as pre emergence fb chlorimuron-ethyl + metsulfuron-methyl as post-emergence fb MW + HW at 45 DAS recorded lower weed dry matter (35.1/36.4) and higher grain yield (2.85/2.80 t/ha).

A field experiment was conducted at KVK, South Tripura during the Kharif season of 2013 and 2014 to study the integrated weed management in direct-seeded upland rice. The predominant weed flora in the experimental field were Amaranthus viridis, Oldenlendia corymbosa, Spilanthes acmella, Ludwigia parviflora, Cleome rutidosperma, Malvestrum coromondalianeum among the broad-leaf weeds, Digitaria sanguinalis among grasses and Cyperus iria among sedges. The results revealed that though the hand weeding thrice at 15, 30 and 45 DAS recorded lowest weed dry weight and the highest grain yield, it was not economically viable. The pre-emergence application of pendimethalin at 1.0 kg/ha at 2 DAS + bispyribac-sodium at 25 g/ha at 20 DAS recorded the highest net returns and return per rupee invested and appeared to be the most promising and remunerative weed management practices for direct-seeded rice under Tripura condition followed by pendimethalin at 1.0 kg/ha at 2 DAS + one hand weeding at 30 DAS.

A field experiment was conducted during Kharif, 2013 and 2014, Collage of Agriculture, Rajendranagar, Hyderabad in Telangana state. Fourteen weed management practices were evaluated in a randomized complete block design, replicated thrice. Significantly higher grain yield (6.9 t/ha) was obtained with either hand weeding twice at 25 and 45 DAT or pyrazosulfuron-ethyl 20 g/ha at 3 DAT followed by manual weeding at 25  DAT (6.8 t/ha) or pretilachlor  750 g/ha as pre-emergence (PE) at 3 DAT followed by metsulfuron-methyl + chlorimuron-ethyl  4 g/ha as post-emergence (PoE) at 25 DAT (6.6 t/ha) or  bispyribac-sodium 20 g/ha + metsulfuron-methyl + chlorimuron-ethyl 4 g/ha as PoE at 25 DAT (6.3 t/ha). However, significantly higher net returns (Rs./ha) and B:C ratio were recorded with pyrazosulfuron-ethyl 20 g/ha at 3 DAT followed by manual weeding at 25  DAT of (Rs. 69788,  B:C 2.79), pretilachlor  750 g/ha as PE at 3 DAT followed by metsulfuron-methyl + chlorimuron-ethyl  4 g/ha as PoE at 25 DAT  (` 67646, B:C 2.77), hand weeding twice at 25 and 45 DAT (Rs. 68720, B:C 2.68), and  bispyribac-sodium  20 g/ha + metsulfuron-methyl + chlorimuron-ethyl  4 g/ha as PoE at  25 DAT (Rs. 62299, B:C 2.58).

A field study was conducted in an Inceptisol with summer season rice to evaluate the degradability of different post-emergence herbicides applied alone or in combinations in terms of microbiological characteristics of rhizosphere soil. Five different herbicides (bispyribac-sodium, metamifop, chlorimurone-ethyl, metsulfuron-methyl and cyhalofop-butyl) were applied as an individual or in combination at post-emergence stage (15 DAS). A wetting agent (agrisol) was also used with some herbicides to increase the effectivity of applied herbicides. Application of different herbicides had inhibitory effect on microbial population and their activities in soil after application, but their effects were not pronounced and the soil properties were restored. Although herbicides applied at different rates but their degradability was almost equal and they took only 30 days or less period for complete degradation except cyhalofop-butyl and bispyribac-sodium + metamifop, which ware applied 80 g and 140 g/ha, respectively and found completely degraded before harvest.

A field experiment was conducted during 2011-12 and 2012-13 at G.B. Pant University of Agriculture &Technology, Pantnagar to study  the effect of different rates of pre-mix of pinoxaden 2.53% + clodinafop-propargyl 2.53% on population and growth of weeds and grain yield of wheat. Major weed species identified in the experiment were Phalaris minor, Avena spp., Chenopodium album, Anagallis arvensis, Polygonum plebeium, Melilotus indica, Coronopus didymus during both the years. The lowest density and biomass of grassy weeds were recorded with pinoxaden 2.53% + clodinafop-propargyl 2.53% at 60 g/ha. However, it was ineffective against broad-leaf weeds. Maximum grassy weed control efficiency (100%) was observed with pinoxaden + clodinafop-propargyl at 60 g/ha closely followed by its lower dose applied at 50 g/ha and pinoxaden at 50 g/ha. Pre-mix of pinoxaden 2.53% + clodinafop-propargyl 2.53% at 60 g/ha produced highest grain yield (4.5-4.6 t/ha). Uncontrolled weeds caused 55.7 and 52.2% reduction in grain yield of wheat when compared with weed free conditions during 2011-12 and 2012-13.

Sugarcane being a widely spaced crop offers considerable space for cultivation of short duration intercrop. In sub-tropical India, sugarcane planted in autumn accounts for higher productivity due to extended period (approximately 12–16 months) of vegetative growth, but its feasibility is only possible if some intercrop especially wheat in Rabi season is sown as it can help farmer in generating additional income in midway of sugarcane season. Two rows of wheat has already been recommended in the north – western India, but the success was marred due to lack of suitable weed control methods in sugarcane – wheat intercropping system. Twelve weed control treatments including ten applications with post-emergent herbicides i.e. sulfosulfuron 25 g/ha and 37.5 g/ha, pinoxaden 50 g/ha and 75 g/ha, readymade blend of sulfosulfuron + metsulfuron 30 g/ha and 45 g/ha, readymade blend of mesosulfuron + iodosulfuron 14.4 g/ha and 21.6 g/ha, metsulfuron 5 g/ha , carfentrazone-ethyl 20 g/ha, a weed free treatment with two hoeings at 3 and 6 weeks after sowing wheat (WASW) and an unweeded control (no hoeing and no herbicide application) were evaluated for three years from 2008-09 to 2010-11 in randomized block design with three replications. The objective of the experiment was to identify the best possible method of weed control for maximizing the productivity of sugarcane wheat intercropping system. All the chemical and cultural weed control treatments including the application of herbicides and manual hoeings suppressed the weeds efficiently as compared to the unweeded control. Among the herbicidal spray, application of sulfosulfuron 25 g and 37.5 g/ha recorded the lowest pooled dry matter of weeds and thus exhibited the highest weed control efficiency (mean of three years) (61.2% and 63.5%, respectively). The highest pooled cane equivalent yield of 92.7 t/ha was recorded with sulfosulfuron + metsulfuron 30 g/ha. Application of any herbicide at a higher dose than normal, could not supplement additional millable canes and sugarcane yield. Application of readymade blends of sulfosulfuron + metsulfuron 30 g/ha and mesosulfuron + iodosulfuron 21.6 g/ha produced pooled intercropped wheat yield of 3.41 and 3.49 t/ha which surpassed the 3.35 t/ ha of wheat yield achieved with two manual hoeings at 3 and 6 WASW. The cane quality was not affected by application of any herbicide.

A field experiment was conducted at College of Agriculture, Gwalior, India during Rabi (winter) seasons of 2014-15 and 2015-16 to evaluate the bio-efficacy of different herbicides to control diverse weed flora especially Phalaris minor in wheat. The experiment was laid out in a randomized complete block design, replicated three times, and consisted of 12 treatments including four treatment as pendimethalin (0.75 kg/ha) as pre-emergence (PE); sulfosulfuron (0.025 kg/ha), metribuzin (0.21 kg/ha), clodinafop (0.06 kg/ha) as post-emergence (PoE) used individually and six of different herbicidal combinations as pendimethalin + metribuzin (1.0 + 0.175 kg/ ha PE), pendimethalin + sulfosulfuron (1.0 + 0.018 kg/ha PE and PoE), sulfosulfuron + metsulfuron (0.03 + 0.002 kg/ha at 5 WAS), pinoxaden + metsulfuron (0.06 + 0.004 kg/ha at 5 WAS), mesosulfuron + iodosulfuron(0.012 + 0.0024 kg/ha at 5 WAS), clodinafop + metsulfuron (0.06 + 0.004 kg/ha at 5 WAS), weedy check and as two hand weedings at 30 and 60 DAS. The highest mortality of weeds and the maximum grain yield of 5.00 t/ha and 4.07 t/ha with 38.2%, 31.0% increase in grain yield over weedy check were recorded with two hand weedings at 30 and 60 DAS (weed free) followed by herbicidal combination as pinoxaden + metsulfuron (0.06 + 0.004 kg/ha at 5 WAS) as PoE application during 2014-15 and 2015-16, respectively. Whereas, the highest B:C ratio of (3.69) was obtained with pinoxaden + metsulfuron (pre-mix) followed by sulfosulfuron + metsulfuron (3.67).

An experiment on evaluation of herbicides in greengram and their residual effect on succeeding mustard crop was conducted at Research farm of Department of Agronomy, CCSHAU, Hisar during Kharif 2013 and Rabi 2013-14. Weed flora of the experimental field was dominated by Echinocloa colona (78%), Cyperus rotundus (18%) and other weeds (4%) at 30 DAS. Pre-emergence application of ready mix (RM) imazethapyr + pendimethalin at 1000 g/ha provided good control (80%) of Echinocloa colona up to 30 DAS. At 60 DAS, imazethapyr + imazamox (RM) at 80 g/ha applied at 3-4 leaf stage provided maximum control of weeds, which was at par with two hoeings employed at 20 and 40 DAS. Post-emergence use of imazethapyr + imazamox (RM) at 60-80 g/ha exhibited 70-80% control of weeds with slight crop suppression which mitigated within 10-15 days after spray resulting maximum  crop growth and  seed yield. Early post-emergence application of imazethapyr at 50, 60  and 70 g/ha although caused mild injury to greengram in terms of yellowing of leaves and stunted crop growth up to 30, but it diminished within two weeks. Maximum seed yield (1078 kg/ha) of green gram was obtained with two hoeings at 20 and 40 DAS followed by imazethapyr + imazamox (RM) at 80 g/ha and imazethapyr at 70 g/ha applied at 3-4 leaf stage. All herbicides, irrespective of their dose and time of application, did not cause any injury to succeeding mustard crop due to high rainfall (594 mm) during crop growing season that resulted in to enhanced microbial degradation of herbicides.

A field experiment was conducted for two consecutive Kharif seasons of 2014 and 2015 at research farm of AICRP-Weed Management, AAU, Anand to study the integrated weed management in cotton under irrigated condition. Pre-emergence application of pendimethalin 1000 g/ha fb hand weeding twice at 20 and 50 DAS, and pyrithiobac-sodium + quizalofop-p-ethyl (62.5 + 50 g/ha) as PoE fb directed spray of glyphosate 2000 g/ha at 60 DAS recorded significantly lower weed dry biomass as well as higher seed cotton yield and benefit cost ratio as compared to rest of the treatments. The weed control efficiency of these treatments proved to be 90 and 86% during 2014 and 2015, respectively.

Earthworm population, soil organic carbon content and β glucosidase enzyme activity in the soil are considered as the indicators of soil quality and biomarkers for toxicity and bioaccumulation assessment. Hence, field experiments were conducted during first crop season (Kharif 2014) and second crop season (Rabi 2014-15) to study the impact of pre- mix herbicide mixtures bispyribac-sodium + metamifop and penoxsulam + cyhalofop-butyl on earth worm population , soil organic carbon content and β glucosidase enzyme activity in soil. The experiments were conducted in randomized block design with 12 treatments and three replications at Upaniyoor Padashekaram in Thiruvananthapuram district of Kerala, India. The treatments were bispyribac-sodium + metamifop at 60, 70, 80 and 90 g/ha, penoxsulam + cyhalofop-butyl at 120, 125, 130 and 135 g/ha, bispyribac-sodium applied alone 25 g/ha, penoxsulam applied alone at 22.5 g/ha, hand weeding twice and weedy check. All the herbicide treated plots registered earthworm population at par to weedy check and hand weeding. The organic carbon content in soil was higher in herbicide treated plots as compared to weedy check at all the stages of crop growth. Herbicide treated plots were comparable to non-herbicide treated plots with respect to glucosidase activity. It was concluded that the pre-mix bispyriibac-sodium + metamifop and penoxsulam + cyhalofop are environmentally safe.

Most of the farmers shifted to direct-seeded rice (DSR) from conventional puddled-transplanted system. One of the major challenges in DSR is weed management, which reduces the productivity of the rice system significantly. Therefore, many herbicide combinations are being tried for broad-spectrum control of weeds. In the present study, field experiments were conducted during Kharif 2013 and 2014 to know the herbicides efficacy when used in mixture using dose-response curve in DSR. The treatments comprised of tank-mix combinations of two herbicides viz. fenoxaprop (0, 30, 40, 50, 60 g/ha) and metsulfuron (0, 2.5, 3.0, 3.5, 4.0 g/ha) to control grassy and broad-leaved weeds, respectively in DSR. Among many non-linear dose-response models, hill model was found to be the best for the data. Results revealed that when fenoxaprop applied in mixture with metsulfuron, its efficacy increased/decreased 4-5% during both the years. Further, when metsulfuron was applied in mixture, its ED50 value was increased from 3.43 to3.62 g/ha as compared to its alone application. Thus, the study revealed the presence of antagonistic effect of fenoxaprop on metsulfuron when used in mixture, which ultimately resulted in reduced efficacy in terms of pre cent weed control.

Field experiments were conducted at Viswavidyalaya farm, Jaguli, Nadia following system intensification (SI) package of practices during 2011-2016 on pre-Kharif black gram (Vigna mungo) and green gram (Vigna radiata) – Kharif direct-seeded puddled and transplanted rice (Oryza sativa) – Rabi potato (Solanum tuberosum) and onion (Allium cepa) crop sequences. Balance nutrition of N:P:K:Neem cake at recommended doses were used along with judicious water in critical crop growth stages and ecosafe green labelled pesticides for insect and disease management. For annual planning of weed pest management (APWPM), glyphosate 71 SG + oxyfluorfen 23.5 EC mixture at 1000 g/ha was used after pre- Kharif crops besides the application of selective pre-emergence (PE) organic herbicides treatment wise in different crops along with HW, post-emergence (PoE) herbicides and weedy check as standard. The results revealed that PE herbicide treatments recorded 30.5 and 10.3% more productivity over PoE herbicides treated plots and 38.4 and 60.0% over weedy check in blackgram and greengram, respectively. The corresponding values were 2.74 and 5.14% and 32.7 and 31.0% in direct seeded puddled and transplanted rice, respectively. In Rabi potato and onion, these figures were 21.1 and 30.4% and 42.0 and 49.0%, respectively. The soil microflora population at harvest recorded increasing in all PE herbicide used plots though an initial decreasing trend upto a month.

A field experiment was conducted to study the herbicidal management of Leptochloa chinensis (L.) Nees. during Rabi season in a farmer’s field at Pullu in Thrissur district during the period November 2012 -March 2013. Post-emergence application of fenoxaprop-p-ethyl 60 g/ha or cyhalofop-butyl 80 g/ha can be recommended in L. colona infested fields. Wherever  this weed is not a problem, bispyribac-sodium 30 g/ha can be recommended.

The study was conducted to assess the allelopathic potential of three basmati (PR 115, PR 124, PR 118) and three non-basmati (Pusa Punjab Basmati-1509, Punjab Basmati-3 and Basmati-386) rice varieties against germination and seedling growth of Echinochloa crus-galli, E. colona and Phalaris minor. Shoot extracts (5%) of non-basmati rice varieties prepared from 50 days old plants had more detrimental effect on germination and seedling growth of E. crus-galli as compared to basmati rice varieties. Variety ‘PR 124’ reduced E. crus-galli germination to 10% and seedling vigor index by 95.8% as compared to control. Root extracts (5%) of basmati varieties had higher allelopathic potential against germination and seedling growth of E. crus-galli than non-basmati varieties. Root extracts (5%) of ‘Punjab Basmati- 3’ affected germination and SVI of E. crus-galli most severely. Aqueous extracts of rice varieties also significantly reduced germination of E. colona and P. minor.

The experiment on weed control in rice bean was conducted at Hebbal, Bengaluru for three years 2012, 2013 and 2014 using pre- and post-emergent herbicides along with manual weeding. Results revealed that the weed free control treatment recorded the lower weed count (11.11/m2), weed dry matter (10.6 g/m2) with higher weed control efficiency (95.3%) and seed yield (1.42 t/ha). The higher B:C ratio of 2.62 was recorded with pre-emergence application of pendimethalin 1.0 kg/ha + one hand weeding at 5 weeks after sowing (WAS) followed by pre-emergence application of oxyflurofen 50 g/ha + one hand weeding at 5 WAS (2.61).

This study was conducted with the aim to understand the effects of tillage practices and Rabi crops on weeds in rainfed rice based cropping system of Chhattisgarh. Significantly lowest weed density, biomass and weed growth rate across all the growth stages under ZT direct drilling of seeds and fertilizers at 2nd days after harvesting (DAH) of rice as compare to other tillage practices. Among the Rabi crops, significantly lowest weed density, biomass and weed growth rate at all the growth stages except 30 DAS were observed with safflower crop. The combination of ZT direct drilling of seeds and fertilizers at 2nd DAH of rice and safflower can be used for better management of weeds   in rainfed rice based cropping system.

To study the floristic composition of weeds in wheat, 292 fields were surveyed in fourteen wheat growing districts of Haryana state during January–March 2012 and 2013. In all, 21 weed species (4 grassy and 17 broad-leaf) were found to infest wheat fields in Haryana. Grassy weed Phalaris minor was most dominant weed with IVI values of 43.2-97.7 in all the surveyed districts except Bhiwani, Mahendragarh and Rewari. Another grassy weed, Avena ludoviciana showed its presence with a RD of 0.5-21.7%  and IVI values of 1.5-43.4%  in south-western districts of Haryana. Grassy weeds of moist soils Polypogon monspliensis and Poa annua showed their presence only in north-eastern districts. Chenopodium album and Chenopodium murale, Trigonella polycerata, Melilotus indica, Rumex spinosus, Fumaria parviflora and Asphodelus tenuifolius were dominating broad-leaf weeds in south-western districts. Robust dicotyledonous weed Malva parviflora, adherent to heavy textured soils and zero till planted wheat, was mainly confined in Ambala, Karnal, Kurukshetra, Rohtak, Sonepat and Fardiabad districts. Convolvulus arvensis- a broad-leaf climber in all districts except Ambala and Karnal.

Rigid ryegrass (Lolium rigidum Gaud.) is a weed that caused significant losses in yields. The results showed that the density of ryegrass varied depending with the climatic regions and increased with increasing of rain. However, the density of this weed increased to the lower semi-arid to the sub-humid climate regions. Maximum infestation (657 plants/m²) of ryegrass was recorded in sub-humid against 9 plants/m² in the lower semi-arid climatic regions. Study of the correlation showed that the yield losses were highly correlated with density (r = 0.92847 and p=0.0001) with an exponential equation y = 109,56 e-0,001x. The results of the field trials showed that pre-mix mesosulfuron-methyl 7.5 g/ha + iodosulfuron-methyl-sodium 7.5 g/ha, pyroxsulam 23.3 g/ha and fenoxaprop-p-ethyl 64 g/ha + iodosulfuron-methyl-sodium 8 g/ha and chlortoluron 2400 g/ha controlled ryegrass effectively. At some locations, herbicides ACCase inhibitors (pinoxaden at 45 g/ha, diclofop-méthyl at 625 g/ha + fénoxapropo-p-ethyl at 50 g/ha and tralkoxydim at 320 g/ha) and ALS inhibitors (sulfosulfuron75% at 26.6 g/ha and flucarbazone sodium 70% at 43 g/ha) showed poor efficacy which may be due to the development of resistance in rigid ryegrass in many locations of Tunisia.

A laboratory experiment was conducted to study the effect of rice straw on the germination and seedling growth of four major weed species of wheat viz. Phalaris minor, Vicia sativa, Medicago denticulata and Lathyrus aphaca. Straw of three rice genotypes, Pant Dhan 16, UPR 2962-6-2-1 and UPR 2992-17-3-1, was added to petri dishes at two different doses (1g and 2g) on which weed seeds were allowed to germinate. It was observed that germination and seedling growth of all the four weed species was adversely affected by rice straw. Straw of the rice genotype UPR 2962-6-2-1 had maximum inhibitory effect and among the weed species Phalaris minor and Medicago denticulata were more sensitive to rice straw. Analysis of phenolics content of rice straw revealed maximum phenolics in the genotype UPR 2962- 6-2-1.  This shows the potential of rice straw incorporation in soil for weed management.

Zero tillage sowing of maize with residue mulching was found a viable alternatives method of crop establishment as compared to conventional raised bed sowing without residue. Thus, zero tillage sowing of maize with residue mulching resulted in lower weed infestation, higher productivity and economics returns. Atrazine 750 g/ha (as pre-emergence) fb 1 HW was effective in controlling weeds in maize crop.

The dominant broad-leaf weeds in the experiment field were Ageratum conyzoides, Amarantus viridis,Chromalaena odorata,Commelina bengalensis, Phyllanthus niruri and Mimosa spinosa. Cyperus rotundus and Cyperus iria were dominant among sedges. Among grassy weeds, Cynadon dactylon,Digitaria sanguinalis, Eleusine indica, Echinochloa colona were most dominant in blackgram. Hand weeding at 25 and 45 DAS gave maximum decrease in weed density, dry weight of weeds and recorded the highest growth and yield of blackgram; followed by application of pendimethalin 0.75 kg/ha fb 1 hand weeding at 25 DAS. Among the fertilizer doses, application of 40 kg/ha P2O5 + 40 kg/ha K2O recorded the highest seed and stover yields.

A leaf spot disease caused by Pseudocercospora sp. on Parthenium hysterophorus L. has been recorded for the first time from the world during the surveys conducted between 2004 to2014.

An experiment was done to see the allelopathic effect of Parthenium hysterophorus on the seed germination and seedling growth of maize (Zea mays) in laboratory conditions. The results showed that seed germination was negatively affected by the aqueous stem extract of Parthenium in different concentrations (15, 25, 50, 75 and 100%) when compared to control condition. Seed germination in control was 100% whereas this value was 3.33% in 100% of stem extract. Stem extract of P. hysterophorus on shoot length was more affected than the root length. T-test values for root length between control and 50, 75 and 100% were positively and significantly different at p<0.001; and for shoot length these values for different treatments were significantly different at p<0.001.

A common feature of pathogenic fungi to cause disease in plant is the necessity to pass through the plant cell wall, an important barrier against pathogen attack. To this end, fungi possess a diverse array of secreted enzymes to depolymerize the main structural polysaccharide components of the plant cell wall, i.e. cellulose, lignin and pectin. In the present investigation, six pathogenic fungal species such as Alternaria sp. PMK1, Alternaria sp. PMK2, Alternaria macrospora MKP1, Alternaria macrospora MKP2, Alternaria macrospora MKP3 and Alternaria macrospora MKP4 were isolated from diseased leaves of Parthenium plant and found to be pathogenic to this weed. Isolated fungi were examined for the presence of cellulolytic, pectinolytic, amylolytic and ligninolytic activity. Presence of enzymatic activities of these fungal indicating the importance of the cell wall degrading enzymes in pathogenicity against Parthenium weed.