Since Dichondra grass is a very sensitive grass and you do not ever want to use a herbicide containing 2-4D on it, it can be difficult to find the right products to recommend. For best results as a post emergent, it is recommended that you pull weeds by hand. Bensumec 4LF Herbicide is labeled to treat poa annua and has been proven very effective. Please read page 2 of the Bensumec 4LF label for detailed application instructions. Hope this helps and please let me know if there is anything else I can do to assist you.
Typically you want to mow the lawn at least twice before applying herbicides such as Bensumec 4LF to be sure the grass is well established and there are no seeds left to germinate.
With Bensumec 4LF Herbicide, the type of weed you are wanting to prevent will determine how many applications can be done per year. Generally, one application in the Spring will be enough per season.
Bensumec 4LF applications must be made prior to the emergence of weeds from the soil. Most weeds germinate when soil temps reach 55 degrees or above consistently. If weeds have already emerged, it is too late to apply Bensumec or any other pre-emergent. We recommend contacting your local cooperative extension office for recommendations on the best times to apply weed control products in your area.
Bensumec 4LF Herbicide does not require the use of a surfactant when used on Bahiagrass or any other blend per the product label.
Bensumec 4LF Herbicide should be applied in the spring and in the fall right before soil temperatures drop below 70 degrees. If the germination of poa annual, crabgrass and other annual weeds extends into late summer and early fall, a 2nd application of Bensumec 4LF at the specified rates should be applied 4-5 months after the initial application.
Refer to page 2 of the product label for single and split application rates.
Bensumec 4LF Herbicide states on the product label: Any material that provides effective control of annual grasses may affect new lawn grass seedlings which germinate after treatment. Do not reseed within 4 months after application.
The only product that can be applied as a pre-emergent around the same time as seeding Fescue is the Tenacity which is labeled to suppress poa annua as a pre-emergent and can prevent crabgrass.