Tenacity Herbicide would be a great option for you to control crabgrass, and yes it is advised to use a dye like Turf Mark Blue with it so you can make sure to not overlap if you plan to do a broadcast application on the property.
You will want to wait until the newly germinated turf has been mowed two times or four weeks after emergence (whichever is longer) before making a postemergence application with Tenacity Herbicide to the new cool season turf. For the most effective Bentgrass control, you will need to reapply Tenacity Herbicide at two to three-week intervals for up to three applications. Be sure to apply with a NIS surfactant. Making applications in late summer/early fall just before new growth is very effective in controlling bentgrass.
It is not recommended to use a hose-end sprayer to treat your lawn with Tenacity Herbicide or any other herbicide. The problem with using hose-end sprayers is that they are not very accurate and you can wind up dispensing more or less product than recommended per area and that can lead to less than desirable results.
Tenacity Herbicide is labeled for use on Tall Fescue, Kentucky Bluegrass, Centipedegrass, Buffalograss, Perennial Ryegrass, Fine Fescue, St. Augustine Grass, so no it will not kill the fescue in your Kentucky Bluegrass lawn. Tenacity is a systemic pre-emergent and postemergent herbicide for the selective contact and residual control of weeds in turfgrasses. When applied as a pre-emergent, Tenacity Herbicide should be applied before soil temperatures reach 55 degrees.
You can spot treat the fescue with a non-selective herbicide such as Killzall and reseed with bluegrass.
Tenacity is labeled as a pre and post emergent for crabgrass but only as a post emergent for nimblewill. The most effective product to control nimblewill pre-emergently has been removed from the market (MSMA). We have had a lot of folks report that Dimension does a pretty good job pre-emergently but since the product is not technically labeled for nimblewill we cannot legally recommend it for this use.
For best results, do not apply Tenacity Herbicide when rainfall is forecasted to occur within 48 hours.
Tenacity Herbicide is labeled for application for post-emergent control of Nimbleweed to established cool season turf. Per the product label, you may need a second application after 2 to 3 weeks. Apply to young, actively growing weeds, and be sure to use a surfactant such as Southern Ag Non-Ionic surfactant for post-emergent applications.
Tenacity Herbicide may be applied when soil temperatures are around 55 degrees or higher for post emergent control. If you are using a pre-emergent you would need to apply before soil temps reach 55 degrees.
The best temperature range to apply most herbicides, including Tenacity, is between 65-85 degrees.
Tenacity Herbicide should not be applied in a mist blower/fogger. It can be applied with a hand pump sprayer or backpack sprayer for more accurate applications to the listed turf.
After further information from the manufacturer they have verified that to making a pre-remergent application with Tenacity you will need to apply a post emergent application once you detect germination of the weed itself. Syngenta recommends to apply no more than 3 application per year.
No, Tenacity Herbicide is not organic.
Tenacity Herbicide if stored in a cool dry area will last up to 3 years. It sounds like you need to purchase fresh product. The mix rate you are using is correct.
If you have already seeded, then you do not want to apply Tenacity Herbicide to the newly seeded turf until is has been mowed two times or four weeks after emergence (whichever is longer) before making a postemergence application.
Since Tenacity is an effective herbicide for weed control prior to or during seeding of certain turfgrasses during turf renovation and the water is only acting as the carrier for the solution to get into the weeds, you should be ok to reseed if you are happy with the results. For post emergent applications, you will need to wait for the turf to be established after 2 mowings to reapply.
Tenacity Herbicide would be a great product to use to treat for nimbleweed and can safely be used in fescue and other cool season grasses.
When using Tenacity Herbicide, the amount of water is not what is important; the right amount of product is. The rate for 1000 square feet is 1 teaspoon. The will mix in 1-2 gallons of water. Please let me know how much area you are treating to give you the best rate.
The rate of the surfactant is 1-2 teaspoons per gallon of water. For 26 gallons of water, the rate of surfactant is 26-52 fl oz.