Okay, it is time. For any and all winter lawn weed preventer people, the right time to use a pre-emergence herbicide is right now. Yesterday would have been fine. So will next weekend. But try not to tarry any longer.
I think the hardest part of using lawn herbicides is psychological. The cool season weeds just don’t matter until sometime over in the spring. That’s when fast growing and blooming clumps of clover, henbit and chickweed along with patches of annual bluegrass get on our nerves. I am talking about annual weeds; each plant is a new one that comes from a seed each year. Right now it’s out-of-sight, out-of-mind to worry about weeds we’ll hardly notice for the next six months. But they will be out there as tiny plantlets down under the dormant turf right on through Halloween, Thanksgiving and Super Bowl XLIX. The only way a pre-emergence herbicide can keep weeds from coming up is to be at work down in the soil before the temperature gets right for weed seed germination. And the only way to accomplish that is to apply the herbicide early enough for it to be diluted and carried by water throughout the top few inches of ground. So now is the time.
September applied premerges work best when evenly distributed over mowed turf grass that has had the last clippings and any leaves removed. And for any older lawns with a thick thatch layer, work on the thatch problem first. That’s because thatch can soak up too much of the herbicide before it can get down to the weed seed zone.
As for granular vs. liquid herbicides, whichever one you can most evenly distribute across the lawn is the way to go. Especially with granules, divide the product in half and put out half in one direction. Put the other half out somewhere between a ninety and forty-five degree angle to improve coverage. It helps with liquids, too. And don’t overdo it; use the correct rate.
I know I shouldn’t ease out of here without reference to which herbicides to use for which weeds. Recall just last week I harped on the need to know pesticide active ingredient names. Well, herbicides are pesticides and I’m sticking with active ingredients. You can find that name on the front of the bag or jug. Or type in the active ingredient for an online search and the trade names will follow. As for which active ingredient for which weed, I rely on Mississippi State University Extension Service’s Control Weeds in Mississippi Home Lawns. Find it online or at the local Extension office. In it, pay attention to 1.) Whether an active ingredient is safe use on your particular species of turf grass, 2.) How the active ingredient is rated for effective control of your specific weeds and 3.) The rate to use.
BTW; paying a licensed professional to apply turf herbicides is certainly an option. The BTW is practice in case I ever take up text or twitter.
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Terry Rector writes for the Warren County Soil and Water Conservation District, 601-636-7679 ext. 3.