Weeds

An experiment was conducted during rabi season of 2011-12 at Junagadh to find out most suitable and economically viable method of weed control in rabi fennel (Foeniculum vulgare Mill.). The dominant weed species observed were Cyperus rotundus L., Chenopodium album L., Digera arvensis Forsk and Asphodelus tenuifolius L. Cav. Results revealed that besides weed free treatment, significantly higher plant height, number of branches/plant, number of umbels/plant, number of seeds/umbellate, test weight, seed weight per plant, and seed and stover yields of fennel were recorded with pre-emergence (PRE) application of pendimethalin at 0.90 kg/ha + post-emergence (POE) application of fenoxaprop-ethyl at 75 g/ha at 45 DAS which was at par with PRE application of pendimethalin at 0.90 kg/ha + hand weeding (HW) at 45 DAS and HW twice at 15 and 45 DAS. These treatments also recorded lower weed density and dry weight of weeds along with highest net returns (81993 & 81442 `/ha) and B:C ratio owing to lower weed index and higher weed control efficiency. However, the highest depletion of weed seedbank was observed with PRE application of pendimethalin at 0.90 kg/ha + HW at 45 DAS.

Globally, India ranks second in terms of area planted under rice (Oryza sativa) and its production as well. Potential to yield is dented due to a lack of inbuilt resistance to different biotic stresses as discernible in ~1000 rice cultivars across the country. Farmers usually rely on applying pesticides that result in several environmental adversities apart from rejection of export consignments due to the presence of chemical residue in grains. Yield losses due to pests of rice in tropical Asia range 25-43%. There is a need to explore alternative integrated input-based management options for judicious use of chemicals with optimal combinations of non-chemical interventions to improve productivity and profitability of rice culture. Field trials were conducted in split-split plot design at Chinsurah, West Bengal during three consecutive rainy (kharif) seasons (2013-15) in transplanted rice. The exploratory objectives were to assess different interventions for alleviating crop biotic stresses and obtaining precise estimate of grain yield as well as economic advantages, and to devise a cost-effective recommendation on need-based integrated pest management (IPM) in transplanted rice. Green manuring with 45-day old Sesbania crop showed a significant (P < 0.05) reduction in infestation of leaf folder, stem borer, sheath rot, sheath blight, false smut, brown spot and bacterial leaf blight of rice compared to control. Both the herbicide (pretilachlor)-treated and green (Sesbania)-manured plots displayed a significant (P < 0.05) suppression of weeds. The diseases (sheath rot, sheath blight, brown spot) of rice were significantly (P < 0.05) reduced by all the treatments targeted for better crop management as evidenced from the sub-sub plots. Rice diseases were best managed by seed treatment with carbendazim 50% WP @ 1.0 g a.i./kg seed, and the effect was more pronounced when the crop was green manured. Significantly (P < 0.05) higher grain yield of rice was recorded with Sesbania manuring, which was as good (P < 0.05) as pre-emergence application of pretilachlor. The herbicide application provided the highest (2.03) incremental benefit-cost ratio (IBCR) among the main plot treatments. Seed treatment with carbendazim followed by (fb) seed bed application of Pseudomonas fluorescens in combination with green manuring prior to rice transplanting in main field fb sequential sprays of chlorantraniliprole 0.4% GR (20 DAT), chlorantraniliprole 18.5% SC (40 DAT) and validamycin 3% L (50 DAT) on the standing crop provided the highest (5656 kg/ha) grain yield with a lower (2.02) IBCR. Contrastingly, only seed treatment with carbendazim recorded the highest (73.85) IBCR. Lower pest incidence and higher grain yields did not fetch greater economic return as apparent from the current investigation. Considering quantifiable and economic impact of inputs, their need-based usage would be a cost-effective proposition to take care of dominant pests in transplanted rice. No comprehensive investigation made such a target-based IPM of most influential crop pests of rice for realizing higher productivity and profitability.

The term weed in its general sense is a subjective one, without any classification value, since a "weed" is not a weed when growing where it belongs or is wanted. Weeds generally share similar adaptations that give those advantages and allow them to proliferate in disturbed environments whose soil or natural vegetative cover has been damaged. Naturally occurring disturbed environments include dunes and other windswept areas with shifting soils, alluvial flood plains, river banks and deltas, and areas that are often burned. Since human agricultural practices often mimic these natural environments where the weedy species have evolved, weeds have adapted to grow and proliferate in human-disturbed areas such as agricultural fields, lawns, roadsides, and construction sites. The weedy nature of these species often gives them an advantage over more desirable crop species because they often grow quickly and reproduce quickly, have seeds that persist in the soil seed bank for many years, or have short life spans with multiple generations in the same growing season. Weed seeds germinate earlier; their seedlings grow faster; they flower earlier; and form seeds in profusion; and mature ahead of the crop they infest. Measures against weeds comprise mechanical (cultivation and moving), cultural or cropping, biological and chemical means. Each of these methods has certain merits and a prudent farmer can make use of one means or a combination of them to control weeds efficiently and economically. In Valsad district mainly wheat, rice, sugarcane, vegetables, fruits, etc. is cultivated crops and weed is a serious problem as they compete with neighboring crops or plants of economic importance and reduce their yield. A total of about 215 weed taxa growing in the different crop area under investigation have been listed of 48 families and of these 180 taxa belong to dicotyledons and 35 to monocotyledons. The dicot: monocot ratio is 4.8: 1.2, means the dicot weeds dominate the crops of the area.

Seven cotton strains, i.e. CIM-78, CIM-80, CIM-81, CIM-84, CIM-95, CIM-96 and Cyto-55 were tested for their resistance against bollworm complex under sprayed and unsprayed conditions at Multan. Cyto-55 and CIM-95 were susceptible, while CIM-78, CIM–80, CIM-81 and CIM-84 were less susceptible to
American, Helicoverpa amigera and Spotted, Earias spp. bollworms. CIM-78 and CIM–80 were susceptible to pink bollworm, Pectinophora gossypiella. CIM-78, CIM-80, CIM-81 and CIM-84 produced better yield under both sprayed and
unsprayed conditions. Cyto-55, CIM-95 and CIM-96 were tolerant against pink bollworm under both conditions, but produced lower yield.

The presence of Solanum rostratum Dunal (Solanaceae) in South America, on the
basis of samples from San Luis (Argentina) and Bogotá (Colombia) is communicated
for the first time. The species is described and illustrated, and biological characteristics
that can promote its spread in local conditions are discussed. It is an annual plant that
reproduces by seeds. It differs from other aculeate wild species of Solanum by their 1-2
pinnatifid leaves, coated with dense and slender spines and stellate hairs, zygomorphic
flowers with bright yellow corolla and a marked heteranthery, with a pollinating, curved
stamen much bigger than the other four, which serve to feed pronubes. This is the first
record for the flora of both countries and South America as a whole. The importance of
their find lies in its huge potential as an invasive, toxic weed.

Study was conducted to assess the phytosociological studies of weed species in paddy at research farm of the irrigation research station, Institute for Agricultural Research (I.A.R), Ahmadu Bello University, Zaria located at Bakolori irrigation scheme Talata Mafara, (Zamfara) State, in the Sudan Savannah ecological zone of Nigeria during 2012 and 2013 wet seasons, A total of 19 and 26 weed species were identified during the 2012 and 2013 wet seasons respectively. The results obtained indicated that Echinochloa colona, Cyperus difformis, Digitaria
horizontallis, were the most densely populated in 2012 while Digitaria horizontallis, Echinochloa colona and Cyperus iria were the most densely populated weeds in 2013. The most important weeds in the 2012 were E. colona followed by D. horizontallis and C. difformis while in 2013 the importance value index (IVI) revealed that the most important weeds within the community were D. horizontallis, E. colona and C. iria. The most important weeds that were associated with the rice crop in the study area are of grass and sedge family.

The present studywas conducted to investigate different weeds of maize (Zea mays L.) and their uses and distribution from 10 different localities i.e. Bagh, Chinarkot, Daro, Dokary, Hayaseri, Kaladog, Kotkay, Lal Qilla, Manial and Mulayano Banda of Maidan valley, District Dir, Pakistan. Forty six weeds species belonging to 22 families were found in maize crop. The dominant family was Poaceae having 7 species, followed by Amaranthaceae with 6 species, Asteraceae 5 species, Cyperaceae, Lamiaceae and Solanaceae with 3 species each, Chenopodiaceae, Fabaceae and Polygonaceae with 2 species each and remaining 13 families with one species each. On the basis of leaf size spectra 20 species (43.34 %) were Microphylls, 15 species (32.60%) Nanophylls, 6 species (13.04%) Leptophylls and 5 species (10.86 %) Mesophylls. The life form showed that there are 23 species (50%) of Therophytes, 11 species (23.91%) of Geophytes and Hemicryptophytes and 1 species (2.17%) was Chamaephyte.

Twelve weed control treatments viz. metribuzin at 0.70 kg/ha followed by (fb) hand weeding at 45 and 75 days after planting (DAP), metribuzin at 0.70 kg/ha fb straw mulch at 10 t/ha fb hand weeding at 75 DAP, pendimethalin at 1 kg/ha fb hand weeding at 45 and 75 DAP, pendimethalin at 1 kg/ha fb straw mulch at 10 t/ha fb hand weeding at 75 DAP, atrazine at 0.75 kg/ha fb hand weeding at 45 and 75 DAP, atrazine at 0.75 kg/ha fb straw mulch at 10 t/ha fb hand weeding at 75 days, oxyfluorfen at 0.30 kg/ha fb hand weeding at 45 and 75 DAP, glyphosate at 1.23 kg/ha fb hand weeding at 45 and 75 DAP, glyphosate at 1.85 kg/ha fb hand weeding at 45 and 75 DAP, hand weeding at 25, 45 and 75 DAP, weed control with organic practice (mulch) and unweeded check were evaluated for weed control in turmeric on silty clay loam soil at Palampur during 2017. Total weed count increased with the age of the crop with highest values recorded at 120 DAP after which the total weed count declined. Contrary to this maximum dry weight of weeds was recorded at 150 DAP which declined at later stage. All the weed control treatments significantly reduced the total weed count and dry weight of weeds as compared to the weedy check. Amongst different herbicide treatments application of metribuzin @ 0.70 kg/ha fb straw mulch fb hand weeding resulted in significantly lowest weed count at all stages of observation as well as at harvest though this treatment was at par with metribuzin @ 0.70 kg/ha fb two hand Weedings. These two treatments along with application of atrazine @ 0.75 kg/ha fb two hand weedings and atrazine @ 0.75 kg/ha fb straw mulch fb one hand weeding resulted in significantly lower dry matter accumulation by weeds as compared to other herbicide treatments. Highest fresh and cured rhizome yield was recorded with the use of metribuzin fb straw mulch fb hand weeding at 75 DAP though this treatment was at par hand weeding and all other herbicide treatments except the treatment in which oxyfluorfen was used. The present study indicates the need of including mulch in any effective weed management strategy for turmeric.

District Malakand lies on the northern side of Khyber Pakhtunkhwa province of Pakistan. The landscape represents both plain and hilly regions. Various kinds of crops are grown among which wheat is cultivated on large scale. In order to explore weed species diversity in the region, a phytosociological survey was conducted in the summer 2014. Such study was required as there has been no such record of weeds diversity of the region. Different fields were selected at various localities of the district. The total number of fields selected was 120 and in each field 10, 1x1m 2 quadrats were laid. A questionnaire was also circulated to investigate about the farming practices and most dangerous species of weeds having greater effect on production and post harvest losses of wheat. Plants were collected from various localities, voucher numbers were given to specimens and other relevant data pertaining to locality i.e., habitat, habit, family, scientific and local names of each species. Mounted copy of each voucher specimen was deposited to the Herbarium of Hazara University Mansehra. This study not only provided first inventory of weed plants but it also helped point out most dangerous species related to wheat yield losses. Results of this study revealed a total of 132 weeds plant species belonging to 110 genera and 42 families. Most of the species investigated were Angiosperms. Family Asteraceae was the richest family related to species diversity with 18 species and 17 genera. It is followed by Poaceae having 16 species and 16 genera. Next in succession are family Brasicaceae with 10 genera and 16 species and family Boraginaceae with 5 genera and 7 species. Other families like Caryophyllaceae, Papilionaceae, Fabaceae, Polygonaceae, Scrophulariaceae and Umbilliferae have 6,6,4,5,4 and 3 species and 6,3,4,3,3 and 3 genera respectively. Species like Silybum marianum (Asteraceae), Emex spinosa (Polygonaceae) and Circium arvense (Asteraceae) are considered to be the most threatening species during the time of harvesting the crop. Further study along this line is the basic part of the on-going project which will provide a base line for the development of agricultural crops in the region.

Weeds are a major threat to biodiversity including in areas of high conservation value. Unfortunately, people may be unintentionally introducing and dispersing weed seeds on their clothing when they visit these areas. To inform the management of these areas, we conducted a systematic quantitative literature review to determine the diversity and characteristics of species with seeds that can attach and be dispersed from clothing. Across 21 studies identified from systematic literature searches on this topic, seeds from 449 species have been recorded on clothing, more than double the diversity found in a previous review. Nearly all of them, 391 species, are listed weeds in one or more countries, with 58 classified as internationally-recognised environmental weeds. When our database was compared with weed lists from different countries and continents we found that clothing can carry the seeds of important regional weeds. A total of 287 of the species are listed as aliens in one or more countries in Europe, 156 are invasive species/noxious weeds in North America, 211 are naturalized alien plants in Australia, 97 are alien species in India, 33 are invasive species in China and 5 are declared weeds/invaders in South Africa. Seeds on the clothing of hikers can be carried to an average distance of 13 km, and where people travel in cars, trains, planes and boats, the seeds on their clothing can be carried much further. Factors that affect this type of seed dispersal include the type of clothing, the type of material the clothing is made from, the number and location of the seeds on plants, and seed traits such as adhesive and attachment structures. With increasing use of protected areas by tourists, including in remote regions, popular protected areas may be at great risk of biological invasions by weeds with seeds carried on clothing.

Applications of 64 times higher rates of azimsulfuron and halosulfuron-methyl failed to reduce by 50% growth of
10 putative resistant (R) Cyperus difformis (smallflower umbrella-sedge) populations collected from rice fields
located in Northern Greece. However, the growth rate of the susceptible (S) population was reduced by 50%
by 1/4 of the recommended rate of both herbicides. The als gene sequencing identified point mutations at Pro-
197 position, leading to amino acid substitution by Ala or Ser of the ALS enzyme. The in vitro activity of the ALS
enzyme indicated that the I50 values (herbicide concentration required for 50% reduction of the ALS activity)
ranged from10.7 to 55.5 μMazimsulfuron and from 6.7 to 50.6 μMhalosulfuron-methyl, whereas the respective
values for the S population were 0.09 and 0.11 μM. These results strongly support that cross-resistance of 10
C. difformis populationswas due to point mutations of the als gene,which resulted in a less-sensitive ALS enzyme.
This study reports the presence of a 1240 bp intron in the C. difformis als gene with the Pro-197 point mutations
near the splice junction.

We present a new methodology for identifying ancient rice arable systems.We create modern analogues of phytolith assemblages of rice weeds from modern fields.These analogues are used as models to understand archaeobotanical samples.We present an analysis of different systems from Neolithic India and China.Rice can be cultivated in a range of arable systems, including upland rainfed, lowland rainfed or irrigated, flooded or décrue, and deep water cultivation. These agricultural regimes represent ecosystems controlled to large degree by agricultural practices, and can be shown to produce different weed flora assemblages. In order to reconstruct early rice cultivation systems it is necessary to better establish how ancient rice farming practices may be seen using archaeobotanical data. This paper focuses on using modern analogue phytolith assemblages of associated crop weeds found within cultivation regimes, as well as in wild rice stands (unplanted stands of Oryza nivara or Oryza rufipogon), as a means of interpreting archaeobotanical assemblages. Rice weeds and sediment samples have been recorded and collected from a range of arable systems and wild stands in India. The husks, leaves and culms of associated weeds were processed for phytolith reference samples, and sediment samples were processed for phytoliths in order to establish patterns identifiable to specific systems. The preliminary results of the phytolith analysis of samples from these modern fields demonstrate that phytolith assemblage statistics show correlation with variation in rice cultivation systems on the basis of differences in environmental conditions and regimes, with wetness being one major factor. Analysis of phytoliths from archaeological samples from contrasting systems in Neolithic China and India demonstrate how this method can be applied to separate archaeological regions and periods based on inferred differences in past agricultural practices, identifying wet cultivation systems in China, dry millet-dominated agriculture of north China and rainfed/dry rice in Neolithic India.

Weeding is a mundane activity that nonetheless affords the opportunity to reorient garden practices in a manner that is more open with regard to relations between humans and non-human beings. Based on a critical analysis of what constitutes a weed and the psychological and political significance of weeding, as well as a consideration of the agency of plants generally, I argue that a more creative or experimental approach to weeding may help to unsettle otherwise habitual and unreflective practices. Enabling individuals to become more open to new ways of doing things in the garden and new ways of thinking about non-human nature, may in turn contribute to the efficacy of collective responses to environmental change.

A field trial was conducted during the kharif season at Agricultural
Research Farm of Trihut College of Agriculture (TCA) Dholi under the
RPCAU Pusa, Samastipur (Bihar) to find out the efficiency of sole and
sequential application of herbicides on weeds and productivity of the
maize crop. A total of eleven treatments viz: weedy check, topramezone
@ 25.2 g ha-1, tembotrione @ 120 g ha-1, atrazine @ 1 kg ha-1fb hand
weeding at 25 DAS, atrazine @ 0.75kg ha-1 fb topramezone @ 25.2 g
ha-1, atrazine 0.75 kg fb tembotrione 120 g ha-1, at razine 1.0 kg ha-1fb
topramezone 25.2 g ha-1, at razine 1.0kg hafb tembotrione 120 g ha-1,
topramezone 25.2 g ha-1+ at razine @ 0.75kg ha-1, tembotrione @ 120
g ha-1 + atrazine @ 0.75kg ha-1, weed free were tested in randomized
block design with three replication. A total of twelve weed species
comprised of four grasses, seven broad leaved weeds and one sedge
were recorded in experiment field. The application of atrazine @ 1.0 kg
ha-1 fb tembotrione @ 0.120 kg ha- significantly reduced the weed density
of grass weeds, broad leaved weeds and total weeds and its dry weight
compared to all other weed control treatments. This treatment had
weed control efficiency (WCE)of 78 % and weed index 2.7%. Thereby,
recorded higher yield attributes and grain yield (6.24 t ha-1), which
was at par with weed free (6.42 tha-1). Therefore, it may be concluded
that application of at razine @ 1.0 kg ha-1 fb tembotrione @ 0.120 kg
ha-1as effective weed control practice for kharif maize.

Cabombaceae is a small cosmopolitan family of aquatic plants that are popular in the aquarium trade on account of their pretty, feathery, submerged leaves. Their flowers, with a diameter about that of a 20 cents Malaysian coin, resemble miniature waterlilies. The floating leaves that develop before flowering, presumably to aid the flowers to stay afloat, are shaped differently from the much divided submerged leaves. They are peltate and thus remind one of a miniature waterlily leaf. Cabomba species are cultivated on a commercial scale in Mantin, Negeri Sembilan, possibly around Kota Tinggi, Johor (Herman, B.G. pers. comm.), Malaysia and in Singapore. A few species of Cabomba are available for sale in aquarium shops in Malaysia sold in bundles of a few stems tied by a rubber band to a lead weight under the trade name of ‘fanwort’. In the last ten years, two species have become naturalised in Malaysia and in Tasik Chini, Pahang, one has already reached infestation proportions and is threatening the aquatic ecosystem and degrading the tourist attraction of the lake. Now we are alerted to their presence, we find that that two Cabomba species, C. aquatica and C. furcata have become widespread in water bodies in Peninsular Malaysia. Both are native to subtropical and tropical regions of South America.

Phytoremediation appears as a very promising
technology for the removal of metal pollutants  from the
environment and at present, the technology becomes
commercially applied throught the world becomes commercially throughout the world.

An experiment was conducted at Agricultural Research Farm, NWFP Agricultural University Peshawar during spring 2007. The experiment was laid out in randomized complete block design having four replications. The tillage systems consisted of no-till (NT), conventional tillage (CT) and deep tillage (DT). Maize type sweet corn (Swat local) was sown on April 23, 2007. The net plot size of 30

Weeds can act as important reservoirs for viruses. Solanum americanum (Black nightshade) is a common weed in Brazil and samples showing mosaic were collected from sweet pepper crops to verify the presence of viruses. One sample showed mixed infection between Cucumber mosaic virus (CMV) and Potato virus Y (PVY) and one sample showed simple infection by PVY. Both virus species were transmitted by plant extract and caused mosaic in tomato (Solanum lycopersicum cv. Santa Clara), sweet pepper (Capsicum annuum cv. Magda), Nicotiana benthamiana and N. tabaccum TNN, and local lesions on Chenopodium quinoa, C. murale and C. amaranticolor. The coat protein sequences for CMV and PVY found in S. americanum are phylogenetically more related to isolates from tomato. We conclude that S. americanum can act as a reservoir for different viruses during and between sweet pepper crop seasons.