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Any method or technique are there to maintain homogenous weed population (approx. equal proportion of weed flora, diversity and density) on entire experimental plots to check the exactly efficacy of weed control method/herbicides.
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I agree with the suggestions provided by @Andrew Paul McKenzie Pegman and @Medhat Elsahookie. Moreover, in field conditions, you may think of re-seeding/planting to maintain the same upto a certain period.
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Is there any post emergence weedicide to control nutsedges (Cyperus rotundus) in cotton without using any shield or perventive nozel? Any weedicide which can kill nutsedge but doesnt harm cotton crop?
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The best post-emergence herbicide in Cotton is Hit Weed Maxx (Pyrithiobac sodium 6% + Quizalofop ethyl 4%) @ 500ml/acre. It should be sprayed between 15-25 days after sowing the crop and weeds should be at 2-3 leaf stage @ Manan Khan
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The herbicides are knowingly or unknowingly sprayed by the farmers in the field crops caused plant injury. This situation has to be recovered and the crops should be saved. What is the recommended antidote for the above herbicides. If anyone knows please tell me with references.
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In Weed Science field experiment, we normally go for statistical transformation of data to bring it near to normal distribution.Most of the time, we go for Square root transformation [ sqrt(x+0.5)]. My question is:
  1. whether the choice of transformation remain same for all set of weed data i.e. sqrt (x+0.5)
  2. If not, under situation we are using the different statistical transformation.
  3. Is it possible we can use different statistical transformations at different stage of observation.
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Mr Himanshu,
As for analysis in ANOVA is concerned, we expect variation between the treatment, whether it is weed-free or weed check or any other treatment. The very purpose of the transformation is to reduce the within treatment variation, rather between the treatment.
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We are looking for feral hemp seeds to use in our ongoing experiments on invasion risk of hemp in Florida (https://programs.ifas.ufl.edu/hemp/). There seems to be a lot of 'wild' populations in the Midwest, U.S., leftover from the industry in 1940s.
Any suggestion for sourcing/ collecting these seeds?
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Hello Susan; I'm very curious to know what finally came of your question. Did you learn what you needed to know? Were you able to act on it? Best regards, Jim Des Lauriers
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It is hard to find information about this theme. I would use the information to have a better understanding of the ecology of this species. This will be framed into a study of resistance to herbicides. I really appreciate you help.
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yes
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25 years ago while replanting a 100-mile gas pipeline north of Reno in BLM lands in a cheatgrass area, at http://www.ecoseeds.com/greatbasin.html discovered that the exotic animal grazing had lowered the soil nutrients and organic matter below the thresholds needed for the local native seedling survival, that you can see at http://www.ecoseeds.com/good.example.html
By finding the soil nutrient thresholds in the top 5 cm, from around the seedlings of the desired native, and then testing the project area soils, and then adding fertilizers and organic matter along with the seeds, was able to get a cheatgrass-free planting in only six months, that remained 100% cheatgrass free for at least five years.
So my conclusion is that cheatgrass, instead of an "invasive" plants, the cheatgrass is what I call a "default" weed, only growing in soil too poor for the local natives and indicating poor soil conditions.
THE QUESTION IS, has anyone else used fertilizers to permanently eradicate other populations of cheatgrass, or added fertilizers to bring the soil nutrient thresholds up, so that the desirable plants are favored, and they can out-compete with the poorer-soil adapted weeds?
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Weeds, particularly the invasive ones, are believe to have numerous negative impact on native species, including species extinction. Are there studies that provide results to support these claims, including the species involved?.
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Please take a look at the following RG link.
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weed science researchers
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Dear Viji N
This Published paper could help you.
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I am doing an herbicide bioassay which involve me mixing herbicide into a pot full of soil.  I need to calculate the amount of herbicide I need to add to the soil in the pot to reach 1ppm of herbicide in soil.  Is there a guide I can follow to do this type of work? I have not been successful finding publications that do this type of work.
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For soil applied herbicides,
Calculate as 1 mg ai. per kg of soil.
For field application, take weight of 15 cm furrow slice in 1 ha area as Bulk Density x 1000000 kg (on an average).
So for 1 ppm conc. = Value of BD kg/ha active ingredient.
For example, a soil having 2.1 g/cc BD will need 2.1 kg of herbicide ai per ha to reach a concentration of 1 ppm.
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With due respect, I would hereby request the scientific brethren to provide me a formula with examples to calculate the "impact" or "degree of impact" of alien invasive plant species in the introduced ecosystem.
I, would, hereby like to re-state that I am in need of a formula. Although, I have found certain formulae, but the variables are not clearly defined.
For example, Parker et al. (1999) suggested I (overall Impact)= R (range) × A (abundance) × E (per capita impact). Now, how to calculate R & E, is not clear!
Again, Lockwood et al. (2007) states I = Ft × Fe × Fs × E; how to calculate Ft, Fe, Fs & E is not stated!
Ricciardi (2003) opines Impact = A × F (ecological function per capita effect) × C (composition of recepient community); but no clarity with respect to calcuation of F!
I am at a loss!!!
Thanking you.
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If you know Elodea nuttallii have seeds in native,please tell me place。thank u very much! 
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thank u @Andrew Paul McKenzie Pegman 。I were doing work on field last  5 months,so i had no chance to reply u。I am puzzling about its seed,could you show me some seeds ?thank u very much
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I am looking for information and protocol to study gene expression in crops under competitive conditions with weeds.
What to consider? and what would be a proper technique to do so?
Any article or tips is appreciated
Kind Regards
Alireza
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Dear Taab
Please find the attached papers related to your request.
All the Best,
Ramin
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I am unable to find a protocol for norflurazon detection in plant tissue. I have only encountered works concerning quantification of norflurazon in soil samples (Essington et al., Comun. soil. sci. plant. anal., 1995) or clear standards (Mueller et al. weed science, 1992). Does anyone now about publications concerning this topic?
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When I think of plant extraction for chemicals I always think of Quechers as a good place to start.  Do a google search for quechers, many companies now provide kits for this type of extraction (Waters, Sigma, Agilent, Restek, Phenomonex...etc)  You would use this protocol to extract the norflurazon from the plant material, then analyze as stated in the soil or water analytical/instrumental method.  See attached link for norflurazon in tobacco using quechers
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Does anybody know where I can get dodder seeds of Cuscuta pentagona or C. reflexa at Germany or within the EU?
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Hi: you can collect from plant that infects with dodder
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I am planning to study the effect of under-sowing cover crops like clover in control of weeds in winter wheat and canola.
My typical climate to see the effects there, is Mediterranean one, preferably.
It is appreciated if anyone can share any data or experience.
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It is interesting to know that the sustainability of cropping systems can be increased by introducing a cover crop, provided that the cover crop does not reduce the cash crop yield through competition. The cover crop may be sown at the same time as a cash crop in the crop rotation.
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I am looking for data on control of Malva sp. in rapeseed. I wonder if anyone has done study on competition between Malva sp and rapeseed/canola. We are dealing with problem of Malva sp. and broomrape in rapeseed.  Any tip and information is appreciated.
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Please check the PDF attachments.
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Weed prevention is a weed management component that prevents weeds from moving in to a new environment. I believe it is different from preventative weed control that aim to prevent weeds from establishing when their propagules are present already.   Considering that weed management is prevention, eradication and control, why is it that weed prevention is not  emphasised in IWM?
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I would guess that the approach to weed management is dependent on who is teaching the course and where the course is being taught. In part it may also be an issue in how to deal with the problem. A grower might want to quarantine all new shipments that come into his area to prevent some weed from invading his field. Yet one grower has neither the political power to make this happen nor the infrastructure to inforce the quarantine. That is the role of governments and police forces. At the point that a grower must do something it is already too late for regulatory weed management strategies to prevent the spread of the weed. Even if borders are secure enough to enable a quarantine approach, there will be smugglers to contend with.
    I would also suggest that by the time a problem has gotten large enough to mobilize the political will to enact a quarantine, that the effort is already too late. The quarantine may slow the spread but that is the best that can be hoped for. The problem is with detection. So I need to prevent a new weed from invading my island. Every car or truck entering my island is carefully washed. All produce is screened, all hay is sterilized.  Yet one seed lands 73 feet past the left side of my house. I have already lost, though I will not know this until several months later when the plant from that seed has produced 800 more and my scout happens upon one of these plants. I just cannot afford to have my entire island searched millimeter by millimeter twice per week to find that one initial plant. The other problem is with collective action. If even one farmer allows the weed to grow on his land, all the neighbors will suffer. Also who pays for taking care of the problem? Some farmers can't pay, others are perfectly happy forcing you to pay.
   The best the grower (as an individual) can do is deal with the problem after the weed has become established. Some places are luck to have a grower that is liked/respected/feared that has political connections and can energize collective action. However, internal conflicts and outside interests make quarantine a difficult proposition at best.
   Partly, the issue is frequency. most of the weeds that growers must deal with are already abundant in their fields. The threat of one new weed from some foreign land is mostly too far away given the 65 weed species that are already at your doorstep.
  Partly, it is economic. So I spent 10 billion to prevent this weed from entering my country. I did this every year for 20 years. This includes border patrol agents to prevent spread by land/air/sea, and shipments of goods that were lost because they could not pass quarantine in time. So what economic benefit have I gained that offsets this cost? Here is what we spent on quarantine _________ and if we had not implemented the quarantine here is the economic damage that would have resulted _______. Was it worth it? Mostly the problem is complex and some people will argue yes and others no. Both will be right depending on where the numbers come from.
This problem is further complicated by perception. So I can go into my field and spray with an herbicide. I have dead weeds and a clear knowledge that I improved my yield this day. In contrast I paid some government another 3% of my earnings to pay some official money to do something. A friend of my neighbor said it was to help stop a new weed that I have never seen from invading. If I don not have strong confidence in my government, this might as well be money to prevent Martians from landing on Earth. So far all the tax dollars spent to prevent a Mars invasion of Earth have worked.
One might also consider what defines a weed. A rancher imports a cactus to act as a fence for cattle. The cactus grows elsewhere and becomes a weed. If only it had stayed just where it was planted.
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I intend to do weed characterization in my station and help my students know how to identify as well as classify weeds in the field. The only one I have is limited. Thanks for your help.
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I want to sincerely thank you all so much for your suggestions. They were indeed very helpful. Thanks.
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Who can help me to identify this plant?
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I agree with José Luis Fernández-Alonso y Sonnia Hill
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A weed survey found in cotton field will be carried out in the different cotton growing regions including plain and Hill districts. What are the accurate methodology to do the survey?
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Ahmed Abd El-Gawad and the Line Intercept Method that he mentions, is almost exactly like the Evens & Love Toe point, except it takes more time to set up, whereas with the Toe Point, you just walk and record what plants the toe of your shoe touches.  
A few dozen people and I tested the Toe point vs the Line Intercept a few years ago in a field, and the Toe Point was about five times faster than the Line Intercept, and produced very closely, the same measured results.
The quadrat method takes even more time, and that is a good method if you are studying the details of a natural plant community and you want to measure very detailed percentages of  plant cover.  I use that method when I want to get every single species, even those that have less than 1% cover within an ecosystem, and the quadrat method misses nothing.  But it takes maybe 20 times the amount of time to do that amount of detail, compared to the Toe-Point.
But for weeds in a cotton field, I hope that you have tried the Toe Point and found it the fastest and easiest method of vegetation cover measurements?  Only 100 paces gives you a very detailed look at what is out there, and that the Toe Point can be done so quickly, means that there is a better chance of getting the data you need on the weeds, instead of having to set up the rquipment to do any of the dozen or so other vegetation cover measurement method. 
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We are interested in natural/safer alternatives to atrazine, for control of pre- and post-emergence broadleaf weeds in large field-corn plots under irrigation.
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Pyroxasulfone, saflufenacil, mesotrione and 2,4-D are some good options available for conventional weed control on corn.
You may want to consult a Weed Control Guidelines of your state.
If you're interested on testing products based on natural compounds, I've attached a publication with some examples you may want to look at.
Good luck on your research!
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I need refereces
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As the plant is evergreen or may only lose some leaves in unfavorable conditions, it is clearly a phanerophyte. However, you might want to keep in mind that Raunkiaer's life forms are mainly created for (highly) seasonal (esp. temperate) floras. Tropical taxa often don't fit or differ extremely in form (cacti, trees, evergreen vines, epiphytes are all phanerophytes!) although being in the same Raunkiaer class. That's why most species are not put in one of those categories. There are other life form classifications though.
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Generally we test all the organic fractions in search of activity based compound (e.g. for pesticidal activity we generally prepare organic fractions for different plant parts and select the most active fraction for phytochemical analysis) but in attached paper there is a short-cut where single plant part is selected for fraction preparation based on activity shown by ethanol extract....is this method same acceptable?
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Dear Dr Lock
Thanks for the comment...I got point
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I'm dealing with weed management practices through allelochemicals for which I've to perform germination bioassays with weed seeds. The problem is seeds of Avena fatua, Chenopodium album, Phlaris minor and Rumex dentatus are not showing germination even I purchased them twice. Any suggestion from experts?
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Try with stratification. Put seeds on 4OC for some period (month-two). It usually improve germination. Also, I mentioned seed have better germination in the period of year when seeds of that species germinate in the field.
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I am doing a research on the above plant, which is a weed in our area. If anyone give some idea on its impact, ecological requirements and the factors that limit its growth and development, please.
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Hi,
In the Caribbean this plant species is considered sometimes as an alien species, sometimes as a native species (!), but it seems that nobody consider it a problem !.  A great number of habitats are now invaded with this plant. Often, people introduce this plant on small ponds, gardens and other standing water habitats.  People consider it as a beautiful plant that increase attractivity of ponds. We do not know any factors really helpful to limit its growth except manual withdrawal. I don't know of any tests carried out in this region against this species.
Since this species is not a problem for boats or for other commercial activity in the West Indies there is no policy considering E. crassipes
Ponds colonized by this species are also the only habitat, in the West Indies, for the dragonfly Miathyria marcella.
Best
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Eleusine indica is currently reported as weed resistant to herbicide at several district in North Sumatera, Indonesia. Is there a new method for analyze weed resistant to herbicide.
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Mr Shergill and Mr Jalaludin, I will collect some seeds of Elleusine indica from some locations. Would you like give me advice? stage seed or age of eleusine that can be collected ? thank you
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A common weed in cassava farms in Northern Sierra Leone. The unknown plant is dominant in crop fields of Kambia and PortLoko Districts, in Northern Sierra Leone. It was discovered during a survey of cassava pests, diseases and weeds. Scientific identification is a problem, please help. 
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looks to me like birds nest fern.
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Anyone who used Parthenium hysteroporous (weed) extracts for the management of insects pests? please attach the publications etc
THANKS
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i did my Ph.D work on Parthenium extracts against onion thrips you can also download my paper published in weed science journal
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Invasive grasses can be controlled by seasonal application of herbicides, soil disturbance and thatch removal. These are all expensive to apply, using man-made machines, and it is difficult to access many areas of the landscape. It seems to me that goats could accomplish the needed thatch removal, soil disturbance and seasonal cover reduction if they were brought into the site a few times a year before the grasses go to seed, and they could access more of the landscape than humans with machines.
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Goats are primarily browsers, and are used to clear invasive shrubs in WI.  I've attached a guide to using goats for brush control from a USDA RC&D group and an article on using goats to clear invasive plants on oak savannas.  You can even rent a goat herd for brush control from a company that specializes in this service in SW WI.  For larger shrubs that may need knocking down for a thorough overbrowsing, we use shaggy highland cattle which prefer browsing to grazing if available.
For grazing out grasses, you may want to look at the succession of grazers we see (or saw) in natural grasslands.  Typically, migratory mixed herds are lead into new, ungrazed areas by equines: horses, asses, and zebras.  Equines can handle very course grasses and will provide the initial grazing and clearing access to more tender, higher quality grass and shoots.  Equids are followed by large grazers like cattle, bison or the large antelope which are in turn followed by smaller "nibblers" like sheep and small antelope.  Knowing this, perhaps you should start your grazing with horses or donkeys and after they've mowed it back bring in cattle or sheep depending on the coarseness of the remaining grasses.  Use sheep for the final overgrazing.   
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hericide resistance
Gene Silencing
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Dear Fungai Mukange
The lesson for future is integrated weed management to reduce the selection pressure.
No single method ever is going to be stable therefore diversity is the key.
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This weed is winter perennial herb appears in early spring. The stems are erect and unbranched with 25-50 cm height. Second photograph (DSC1251) shows whorled leaf arrangement on stem. It has also tubers which usually buried at a depth of 20 cm or greater (fig DSC-1154). Please see attached files for more information.
No information about it's flowers is available at this time.
The photos (except for tuber photograph) were taken on 4/27/ 2015 in the Northwest of Iran.
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After reflexion, it's a Podophyllaceae, like Bongardia chrysogonum ; see http://www.avonbulbs.co.uk/s/bongardia-chrysogonum/52/Product.aspx
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This weed is annual herb appears in winter season (November to march), leaves needle like, fleshy, flower colour white.
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It looks like corn spurry to  me. (Spergula arvensis L.). It is a fairly common weed in the United States and has been recently identified in Alaska.
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Nowadays, allelopathy is topic of interest for weed control. Scientists are isolating the natural phytotoxins/allelochemicals for weed control. How one can justify that isolated allelochemicals will inhibit the growth of weeds only and not of the crop?
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The most important thing would be to test the crop of interest to see if it is susceptible to injury.
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I want to know that from which site or field should we select the susceptible weedlines so as to evaluate the resistance level in any weed species?
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Hi Eajaz,
We collect seed for susceptible checks from non-agricultural areas with no history of herbicide use (e.g. public park, home garden, roadsides, other natural areas, etc.). This seems to work well. I think there are a variety of approaches you can use here, as long as you can justify that the check should be susceptible, I think you should be good.
Scott
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Most scales used only define the extremes, thus the no damage and the plant death characteristic. the intermediates are arbitrary based solely on the discretion of the technician. I am of the opinion that such an approach elevates chances of heteroscedasticicity of the data and makes it difficult to make comparisons for scientists across locations. Moreover, different symptoms are expected for chemicals with different MOA and this should be taken into account by the scoring system.
May interested parties comment on developing a crop specific, robust and versatile scoring system which can minimize the discrepancies likely to be brought about by the arbitrary system
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You seem to have a very good understand many of the limitations with visual phytotoxicity assessments. Additional problems include the issue of many researchers not doing this assessments blind (they take a plot plan with them and know what plots they are rating) so the potential for bias is VERY high. My question would be why use them at all? Because of these problems most journals will not allow publication of papers without additional truly quantitative data such as biomass and yield. Because of this we will use them sometimes as a semi-quantitative way of describing herbicide phytotoxicity but I am not sure of there utility for anything beyond that. However for those that are screening massive amounts of herbicide plots they may be a necessary tool. Looking at other disciplines that have done a better job may be informative - plant pathology in particular has been much more rigorous in there development of scales for plant pathogen symptoms.  This approach probably could be transferred to contact herbicides fairly well. The issue always will be that there are large differences between herbicide MOA and plant species. In addition for many MOA most obvious symptomatology is the cessation of plant growth that requires the comparison of the untreated plots with treated and therefore removes part of the blind rating. So is this impossible - no, but I think one has to consider if the data will really be that much better. 
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Weed management aims at reducing weed densities to populations which do not inflict yield penalties, but not necessarily eradicating the weeds. However, most published work  does not take account of the aspect ETLs and such literature is scarce for most crop-weed interactions. How then can 1 reach a sound conclusion without such information. Secondly, how can growers tell when weeding is due without knowledge of ETLs. What are the rates of occurrences of type I and type II errors in weed management in the absence of ETL data. 
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Weed management costs money and so some kind of economic threshold estimation is wise, but most managers opt for reducing risk, and the thresholds they use often lead to over-investment.  This is unsurprising because penalties for failure can be severe, and weed impacts vary from site to site in ways that are not easily predicted.  Typically a regional analytical approach is taken, but with weeds targeted in a more site specific way.  A competent manager will know that certain weeds are likely on specific site types, and that the consequences of lack of control from those weeds generally justify control.  However, just to be sure they are likely to over-invest.
The question is complicated by the longevity of forest crops.  Have a look at types of responses to site management treatments as outlined in the following papers:
Snowdon, P. and H. D. Waring (1984). Long-term nature of growth responses obtained to fertiliser and weed control applied at planting and their consequences for forest management. IUFRO symposium on site and site productivity of fast growing plantations, Pretoria and Petermaritzberg, South Africa
Mason, E. G. (1991). A forest establishment or regeneration decision framework. Proceedings of the IUFRO symposium on Efficiency of stand establishment operations, Rotorua, Zealand Forest Research Institute Bulletin
Mason, E. G. (1996). "Planning forest establishment operations with a computerised decision-support system: a case study analysis of decision-making over a full rotation." New Zealand Journal of Forestry Science 26.(1/2): 222-234
Mason, E. G. (2005). "Effects of soil cultivation, fertilisation, initial seedling diameter and plant handling on the development of maturing Pinus radiata D.Don on Kaingaroa gravelly sand in the Central North Island of New Zealand." Bosque 25(2): 43-55
Mason, E. G. and P. G. Milne (1999). "Effects of weed control, fertilization, and soil cultivation on the growth of Pinus radiata at midrotation in Canterbury, New Zealand." Canadian Journal of Forest Research 29: 985-992.
Mason, E. G., A. G. D. Whyte, et al. (1997). "A model of the growth of juvenile radiata pine in the Central North Island of New Zealand: links with older models and rotation-length analyses of the effects of site preparation." Forest Ecology and Management 97(2): 187-195.
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Phlaris minor is world known weed of Triticum aestivum while less common in other fields. Similarly other crops have their own weeds. What makes these weeds crop specific? Moreover why most of weeds are herbaceous in nature?
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The term "weed" can be applied to almost any plant, depending on the situation and the perspective of the person referring to a particular plant as being a "weed".  For example, glyphosate-resistant Zea mays could be a weed if it is found growing and competing with glyphosate-resistant Glycine max
Crop-weed associations could be due a number of factors: similarities in growth habit, life cycle, management practices, etc. 
Most weeds tend to be herbaceous because this type of plant tends to have the traits of a fast-growing colonizer that can utilize available resources after a disturbance.  Woody species can be "weedy", but this type tends to appear in later stages of succession. 
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What is the appropriate method to find out the population of a weed?
Is the SAMPLEPOINT will be helpful? 
To say a plant is gregarious in a site is IVI (Importance Value Index) will be useful?
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Sampling weed species largely depends on several factors; including cropping pattern, size of plot or area covered, etc. The most common technique is using ''quadrant'. This can be temporary or permanent (fixed) or movable quadrant. Dimension may vary depending on some of the factors mentioned above. I usually use 0.25m2' or 1m2 for sampling weeds in experimental plots. All weed species within the quadrant are collected, counted and identified according to species type.  I also usually make two or three throws of quadrant per plot. Total count per specie type and for all three throws are added together to give relative abundance of each specie per treatment. In addition, I also usually determine % weed  cover, ease of control and level of aggression per weed specie type. I hope this information can be helpful.
SMKanteh,
Njala University
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Cynanchum acutum is one of the most important invasive plants. To reducing its damage, we should prevent its developement in new areas. But how about an infected garden?
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As i know, the name swallowort is a common name of Chelidonium majus and doesn't use for C. acutum. One of the common names of C. acutum is "Kudzu".
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RNA Seq, Genomics
Each plant in a population has different genetic makeup
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Shahid, therefore biological replicates will normalize such variations and give you probably a better average or conclusions.
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I was interested to study the weed communities in certain area and correlates with climate. What is better to collect climate data during the  year of study or during the past several years and what the best number of years to be expressive?
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climate of one year may be not enough, as climate is changeable, it is better to take in consideration the climate of several years. Of course, there is a relation between distribution, growth performance, etc of your studied weeds.  
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I am looking for software that can be used to calculate leaf area for a plant without damaging the plant. The "destructive method and the graph sheet method" are tedious and time consuming. Does anyone have any experience with this?
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If you are always studying the same species, you can do a calibration curve by measuring actual area, length and width of a leaf, and then you'll only have to measure length and with and enter them in the regression equation
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Mimosa invisa, an invasive weed, has become a very serious problem in my location and I intend to find out how best to control it and at what time the control methods should be introduced. Your contributions will be of great help. Thank you so much.
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Invasive shrubs such as Mimosa diplotricha C. Wright ex Sauvalle (=Mimosa invisa Mart. ex Colla) (Mimo-saceae) that impact negatively on existing plant communities  pose a threat to biodiversity, agriculture and human livelihoods. Mimosa diplotricha is a fast growing, annual (short-lived) or perennial shrubby legu-minous vine native to the Americas.
A number of herbicides such as isoxaflutole (balanced), atrazine, diuron, paraquat, etc. (applied singly or as a mixture) have been recommended for the control of M. diplotricha. In the Pacific Islands, paraquat + diuron applied postemergence has provided good control of M. diplotricha and 2,4-D + atrazine has been applied as an overall spray especially in pasture situations to control young to semi-matured stands. In Nigeria, Alabi et al. [28] reported that atrazine + me-tolachor, bentazon + propanil and acetochlor + atrazine controlled M. diplotricha satisfactorily but reduced the yield of cassava compared to hand weeded control. While it is generally advisable to apply herbicides before the onset of flowering and fruiting, repeated applications may be required depending on type of crops and the ef-ficacy of the herbicides. Melifonwu et al. [30] showed that the application of primextra (a formulated mixture of atrazine and metolachlor) followed by hand weeding were able to achieve considerable control of the weed in cassava fields in southeastern Nigeria.
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Pendymethalin is used mixed with propanil 8-12 days after sowing as pre-emergent for weeds (post emergent for directed seeded rice). Could be a small affectation of rice (in not covered seeds), especially in roots (wider tips) but easily recuperated. Pendimethalin have poor solubility in water, in a normal application it remain in the soil surface and not reach the root area (position´s selectivity). Also can be used as pre-emergent in rice. In Central America is registered for rice.
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I want to evaluate the role of sulfur and zinc on weed emergence in Dry Direct Seeded Rice.
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Thanks
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Based on indigenous knowledge, the seed extract of Cassia tora has been used for its medicinal values to treat various health problems. However, I do not have idea whether this plant is being used commercially or not. What may be the potential commercial utilization of the plant in Indian sub-continent, more specially in Nepal and India? 
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As such Cassia tora has limited industrial uses.However,it can used as greenmanure, may be by drying and making briqutes as concentrated greenmanure
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Can you identify the genus of this plant?
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This plant most likely is Lysimachia debilis Wall. In Flora of Pakistan it is synonymized with Lysimachia japonica - see http://www.efloras.org/florataxon.aspx?flora_id=5&taxon_id=250081204 . However, in Flora of China both species are kept separate - see http://www.efloras.org/florataxon.aspx?flora_id=2&taxon_id=200017002 and http://www.efloras.org/florataxon.aspx?flora_id=2&taxon_id=200017036 . I cannot find good photos of Lysimachia debilis, but as it should look similar to Lysimachia japonica, you may compare also with the latter - see http://www.asianflora.com/Myrsinaceae/Lysimachia-japonica.htm. Compare also a scan of the type specimen of Lysimachia debilis: http://plants.jstor.org/specimen/bm000021265 .
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I'm interested in studying the effect of invasive species on plant community diversity, what are the major impacts can be measured to estimate the effect of invasive species on plant community in certain habitat?
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One colleague found an invasive plant species not recorded previously in Iran and is asking where to submit a short note. I know that for example in phytopathology there are quite a few options to submit a short disease note to record plant diseases from a new host. This also exists for insects but I have no idea about plants. Does somebody have any idea?
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Try the journal called Weed Science.
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Some weeds such as "Cynodon dactylon" have the ability to grow in Siberia and in the hot deserts of Arabia. What is the mechanism of adaptation? Do these plants contain adaptation genes? Can these genes be transferred "transcript" to other plants?
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Like some other weeds, "Cynodon dactylon" can be found growing under very diverse climatic conditions, and you asked for mechanisms of "adaptability".
You got several answers pointing diverse traits that can help a plant to survive in harsh dry and hot climates : C4 and CAM photosyntic physiology, accumulation of organic osmotica, particular fungal symbionts, thick or dense leaves, high concentrations of oils...
Ways of adaptation to stressing conditions are multiple. Each species, each individual displays a specific combination of more or less well adapted traits. Natural selection (and chance) act to retain only some combinations.
Phenotypic plasticity (the ability to change the phenotype in response to changes in the environment) is one of the traits that can be selected, and that can help a species to be "highly adaptable". But it may not be the only way. For instance, seed dormancy offers the ability to survive long periods that are incompatible with vegetative growth (not matter if it is because ot heat or of cold).
What is the mechanism of adaptation?
-- some mechanisms are knwon, some are still unknwon, and facing a new plant, you can not know a priori which mechanisms this particular species has got.
Do these plants contain adaptation genes?
-- of course adaptation is largely due to genes, and to the gene / environment interaction. BUT these genes are not the same in the various species.
Can these genes be transferred "transcript" to other plants?
-- for some of them it may be possible, but their identification will take some time, and you are never sure that the transfer of one gene to an organism with a different genetic background will have the effect that you expect.