How long your pre-emergent herbicide such as Isoxaben 75 WG lasts can certainly vary with rainfall, but if you are using the recommended label rates the you should get weeks to months of control from your applications. Dandelions are a tricky plant to control since the plants can overwinter and last several years. It is recommended to apply Isoxaben in the fall for dandelions, then using a post-emergent called Defendor in the fall as needed and also in early spring prevents remaining plants from growing. Dandelion also starts to germinate with soil temperatures as low as 50 degrees and much more as temperatures rise up to about 77 degrees, so your pre-emergent has to be down before these temperatures to be effective. Dandelion also thrives in thin turf in moist areas, so taking care of your desirable turfgrass will really help to prevent these weeds from competing.
Isoxaben 75 WG Herbicide can be applied at the same time or same day with Prodiamine 65 WDG. We carry one Root Growth Stimulator labeled for lawns, Cutless 0.33G Landscape Growth Regulator but it is not for use by homeowners.
You will want to refrain from mowing 2 days before your application and 2 days after application. Ideally, fescue grass blades should be kept at 2-3 inches long. If you have let your grass grow long during the cold winter months, you can do an initial mowing during the spring, but do not take off more than 1/3 of the length of grass or else the grass may become stressed. Mow every 2-3 weeks as needed and ever week during the spring. Once grass growth slows, typically in the summer months, mow less frequently.
For Sprigged Warm Season Turfgrass, Isoxaben 75 WG Herbicide is recommended to be applied post-sprigging as a preemergence treatment for control of certain broadleaf weeds in warmseason turfgrass.
For newly sprigged warm season turfgrass, the product label does advise that applicators DO NOT apply more than 1 lb per acre of Quali-Pro Isoxaben 75 WG during the establishment phase.
