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Post-emergent control

December 2012

QuestionWith the crazy weather we have had this year, we have a yard full of stickers. Don't remember ever seeing them this time of the year. Would it be ok to spray them now? If yes, what would you recommend?


AnswerThe sticker weeds are normally here this time of year, but this year they are growing faster than normal. The sticker weed is called spurweed and it germinates in the fall, grows all winter and dies in late spring. If you already have stickers, then it is definitely ahead of schedule, since the stickers are the seeds that are produced after it blooms. Pick a mild day with little wind and spray with a broadleaf herbicide containing 2, 4-D. You don't have to spray the entire yard, just where the weeds are. Luckily it is an annual weed, and if you can kill it before too many seeds have set it will reduce the population for next year, but if allowed to grow unchecked, you will have more and more stickers each year.

September 2012

QuestionDue to health and age we down sized last fall and moved to Beebe. We have a weed that is over taking the lawn. Some call it Johnson Grass. Can mow one day and by the next day it's already big again. Is there anything I can do this fall that will prevent it from coming back next spring?


AnswerIf it truly is Johnson grass it is a perennial so a pre-emergent herbicide won't work. Since we lost MSMA as a herbicide, weed grasses are tougher to eradicate, but there are a few options for use during the growing season. Quinclorac is now used and is often mixed with 2,4-D as a broadleaf weed and grass killer. It is tough to kill, so good luck.

June 2012

QuestionWe used a pre-emergent herbicide on our lawn this year and it did not stop the progress of the weed called crabgrass. Is there something I can do to rid my yard of this grass?


AnswerThe standard herbicide for crabgrass control for years was MSMA and it is no longer on the market. We now have products that contain quinclorac for control. However most homeowner products are combined with another herbicide –many have 2,4-D (a broadleaf weed killer) which could burn warm season grasses when applied during the hot summer months –trade names include weed-B-Gone Max, Weed Stop plus Crabgrass Killer and All in One Lawn Weed and Crabgrass Killer. Some products are combined with sulfentrazone—a sedge killer; trade names include Image Kills Crabgrass or Sedge and Grass Killer. Make sure if you are applying herbicides that you read the label beforehand. Follow recommended rates and read if there are any temperature restrictions and that it is safe for the type of lawn you are growing. Many herbicides are not recommended for use on St. Augustine or Centipede lawns. Also, make sure that the lawn has ample moisture before applying chemicals or fertilizers or you could damage the lawn. Don't
spray on a windy day and don't treat the entire yard if you just have a patch here and there—spot spraying would be much safer.

April 2012

Question I have monkey grass in my yard and I think I read recently that you could use roundup on it. I don't have the paper anymore and want to verify this is right.

 AnswerMonkey grass or liriope can be killed, or at least knocked back with glyphosate or Roundup, but be sure to spray only what you want to kill, as it is a non-selective herbicide. If you are growing the running form of liriope—Liriope spicata, it will take more than one spray to slow it down.

February 2012

QuestionI have weeds every year in my lawn that seem to get worse each year. I can't get rid of them. What should I use? I have attached a picture of them

 AnswerThe weed in question is henbit, which is in the mint family and a winter annual. You can kill it now with any 2,4-D based herbicide. Most brand names will include broad leaf weed killer in their title. If you have Bermuda grass as a lawn, you can use a glyphosate product (Round-up) but it is only safe on dormant Bermuda--not any other lawn grasses. I have seen henbit blooming already--a nice purple flower. If you have blooms, you will have seeds, which will come up again next fall.


QuestionI missed the chance to apply a pre-emergent herbicide this October to kill spurweed. Are there any 2.4-D combination products that are safe to use on Centipede grass? I've got Centipede and Bermuda in the problem area. If so, I understand you use it December thru March, at a time when temperatures exceed 55 degrees. Do you agree?

 AnswerSpurweed (Soliva pterosperma), also called lawn burweed, stickerweed, and sandbur has become quite a nuisance in many lawns and I am happy you are preparing to kill it way before bloom time and then seed (sticker) set. There are numerous formulations of two and three-way mixes of 2,4-D, dicamba and MCPP. Make sure you read the label before purchasing that they are safe for southern grasses. Many will give reduced rates of application for Centipede and St. Augustine. You do want a fairly, calm sunny day with temperatures above 55 for best application and control. Spray once and then monitor your weed population and you may need to reapply two weeks later.

February 2010

QuestionMy lawn is part St. Augustine and part Bermuda grass. What is the best pre-emergence to use and what is the best fertilizer that works with both types of grass?

 AnswerThe main reason to apply pre-emergent herbicides for warm season grasses by March 1 is the prevention of crabgrass. Products containing benefin, pendimethalin, or bensulide are all effective. There are numerous product names, but they usually always have crabgrass or weed prevention on the label. All too often we run into weed and feed formulations. If possible, go with a stand-alone herbicide, since Bermuda and St. Augustine will not benefit from a fertilizer application until April, so the fertilizer is more a waste or a boon to your winter weeds. As to fertility, both grasses need a slow release high nitrogen fertilizer since nitrogen is the nutrient used the most by lawns. Look for something with a higher first number and the next two smaller such as 27-3-4. Fertilize both grasses once they are totally green. St. Augustine could be happy with one or possibly two applications of fertilizer, while Bermuda grass will respond well to multiple applications, depending on how often you want to mow.

March 2005

QuestionWeeds are everywhere in my lawn! I seem to have some of everything in bloom it seems. I have not taken care of my lawn in a few years, but the weeds have never been so bad. Is there a reason, and what should I do to kill them now?

 AnswerWinter weeds started early this year, and with warmer weather, they kick into high gear. If they are blooming, they are entering the last phase of their life cycle. Winter annual weeds germinate in the fall, grow all winter, begin blooming in late winter/early spring, set seeds and die. If you can keep them mowed to prevent seed set, that can reduce populations next winter. If you can get a move on it, and spray soon, you can still use a broadleaf weed killer with 2,4-D. The smaller the weed, the easier they are to kill. Try to avoid spraying herbicides when your lawn begins to green up. Grasses are much more sensitive during the transition period from dormancy to active growth, and again when they go from active growth to dormancy in the fall. So, use caution and spray as early in the month as possible. One of the reasons weeds may be worse in your lawn is that you haven’t been taking care of it. A thick, lush lawn tends to have less weed incidence than one that has gotten thin. If soil is exposed to sunlight, weeds take over. If you practice good maintenance this year, with proper fertilization, watering and mowing, your weed problems may lessen in time. Some people look at these early winter weed blooms as wildflowers. You know what they say “one man's weed is another man's wildflower!”

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