Are you referring to herbicide treatments being applied to crop seeds, or herbicides being applied to the soil as a preemergence treatment to prevent weed seed germination?  Your questions is not clear.

Dear Robert.

Thank you very much for Question. Sorry. My interest is on herbicide treatments for crop seeds only. I have worked on preemergence and post emergence treatment of herbicides on field crops. I would like to concentrate "is it possible to treat the crop seeds with herbicide to prevent weed infestation particularly parasitic weeds. If it is so, we can reduce the herbicide usage and cost of cultivation. If you have any idea please share with me.

I hope this helps direct your searches.  A number of papers use acetolactate synthase (ALS) type herbicides as a seed treatment to control Striga spp.  In other works, root-parasitic weeds are controlled in transgenic crops when the herbicide it is resistant to is sprayed on it.  You may find the book in the link of use too.

http://www.springer.com/life+sciences/plant+sciences/book/978-3-642-38145-4

OK.  Most crop seeds will have no parasitic weeds or their propagules attached directly to them.  That's not to say there are never weed seeds present in a bag or container of seeds.  In fact the seed tag of any inspected container of seeds should state the percent weed seeds (by weight) as well as the presence of any noxious (harmful or potentially invasive) weeds, though these practices are dictated by governmental laws and regulations, and those vary from country to country.  Seeds marketed by commercial seed companies frequently have various coatings on them, including fungicides, insecticides, and N-fixing bacterial inoculants (only specific legumes).  These materials are designed to prevent localized attack by various crop pests or, if systemic, provide early protection to the young plants and are not meant to disperse to any extent throughout the surrounding soil.  N-fixing bacteria are placed in direct contact with the seed for entirely different purposes, but again, the organisms in those coatings do not move far from the seeds once placed in the soil. I'm not aware of any seed treatments that include herbicides.  The bulk of the weeds emerging in or with a crop are from the vast storehouse of weed seeds contained in the soil.  When crop seeds are planted, unless they are broadcast uniformly across the land, such as is the case with many forage and turf species, they are typically planted in some sort of row type pattern (with a seed drill or row crop planter).  Consequently, in such a situation it would not be possible to disperse a seed treatment herbicide widely throughout the soil in which the crop is planted.  Of course, the herbicide, depending on its chemical characteristics and various soil characteristics, might be able to diffuse for several centimeters into the surrounding soil such that weed seeds/seedlings emerging very near by might be affected.  This would require that any such herbicide be selective enough that it would only damage the target weed(s) and not the desired crop species.  I just don't see the pragmatism for such an endeavor.

Dear Robert alan lane,

Thank you very much for your response and detailed answer for my query. I would like to mention that, there are several works have been carried out in the world to manage parasitic weeds, for example, striga and orabanche can be controlled or minimized their infestation through herbicidal seed treatment.  Dr.Mahoney has indicated some references about orabanche infestation. This is for your kind information. Once again thanks for your response.

With warm regards

Murali Arthanari

Thank you for pointing those out to me, Murali.  I'm familiar with both of those species, but had never observed them causing significant losses in cultivated crops.  Upon further study, I now see that both can be serious problems in specific crops in certain parts of the world.  In such cases I think the concept of herbicidal seed treatment is very interesting and has potential merit.  My thought processes lead me to consider your question in regards to competitive, but not strictly parasitic, weeds.  Best wishes in your research.

Dear Robert Alan,

Thank you very much for your encouraging reply for my research. I will keep in touch with you regarding my research in future. If you come across any publications related to my research, please send to me. 

With warm regards

Murali Arthanari

check this links maybe help you

https://bioone.org/journals/weed-technology/volume-27/issue-1/WT-D-12-00069.1/Weed-Management-Strategies-to-Reduce-Herbicide-Use-in-Zero-Till/10.1614/WT-D-12-00069.1.full

Article Herbicides as Weed Control Agents: State of the Art: I. Weed...