GOT WEEDS?

• Pre-emergent  - Work to try and prevent weeds from ever growing. 
• Post-emergent  -  Work to try and kill weeds that have already grown. 
• Selective herbicides -  kills certain plants but not others.
• Non selective herbicide -  kills plants they are applied to.

Per Nevada law people spraying for weed control including landscapers and their employees individually who spray for weed control each need a license with / through the Nevada Department of Agriculture (NAC and NRS 555). To obtain this license they must pass exams. A license is also needed to advertise and bid for maintenance contracts that involve weed control applications Source. If someone is violation of the laws they can be fined per NRS 555.530.

To check if someone / a company is properly licensed to advertise and spray for weed control ask them what their license number is and contract the Nevada Department of Agriculture to check if they are licensed and if they are properly licensed. 

The Nevada Department of Agriculture has a PDF on there website about the topic.  

The cost will take into account how long it will take to do the work, how much herbicide is used, what prep work needs to be done, and overtime pay to staff for certian rush jobs.  Sometimes more than one application is needed. 

Sometimes more than one application is needed and it does not last for ever so some people have their landscaping sprayed every few months.  These applications are charged to the customer.  Some unwanted growth requires specific herbicides which cost extra.     

Each herbicide has a different amount of time till it can be "walked on".  This information can be found on the label on the bottle it came in which can sometimes can also be found on the internet.