According to the Tenacity product label you will need to mix 1 tsp of product + 3 tsp surfactant with 2 gallons of water for spot treatments. You will not apply more than 5-8 ounces of Tenacity per acre as a broadcast application. Please click on the product label link for mixing and applications according to the type of turfgrass you have.
Broadcast treatments would be recommended if you are needing to actually treat the entire lawn for pre-emergence, if you are only needing to treat small areas or use as a post emergent then you can spot treat. Consult your local Cooperative Extension Service for more specific applications timings for your local area. Their contact information can be found by clicking the link below.
http://www.ahs.org/gardening-resources/master-gardeners
http://www.csrees.usda.gov/index.html
Tenacity should not be applied with a hose end applicator. Tenacity if not applied evenly across the yard can temporarily whiten your lawn and cause you to not see full control of the weeds you want to eliminate. Also most hose end sprayers will not dial down to the small amounts needed per 1000 sq/ft that the Tenacity requires. Tenacity is best applied with some form of a pump/tank sprayer in even strokes without excess overlapping.
According to the Tenacity product label you will need to mix 1 tsp of product + 3 tsp surfactant with 2 gallon of water for spot treatments, using 1 gallon per 1000 sqft.
The product label states that Bermuda grass is sensitive to Tenacity but it would not be recommended as product to eliminate it since it is not labeled for this use. Turflon Ester would be a better option for removing bermuda from cool season turf.
Tenacity Herbicide will not kill poison oak. Please see Bonide Poison Oak and Ivy Killer, which is designed just for poison oak and ivy.
There are certain products that are susceptible to problems with high pH balances in water. If a product label does not specifically address this issue it is because this particular product does not usually have any issues with pH. The product label for Tenacity does not list anything regarding pH levels.
Once mixed with water you should use the product within 24 hours.