What to do this week –
By Mark Govan, Host “Florida Gardening“
Spring is here! Our temperatures are starting to rise, and our landscapes have begun to respond with new growth. If you have been following my advice, then you should have already pruned your plants to remove any freeze damage or diseased and broken branches your plants may have had. Pruning is necessary to enable our landscape plants and trees to produce healthy new growth and flowers. After pruning your plants, you should have fertilized them to replenish the nutrients they have depleted during the winter months. However, this week I would like to go over some of the weed control questions I have received that may help you keep your landscape healthy and green. Let’s get started.
Broadleaf weeds, weed grasses, and sedges are a major problem in our Florida lawns. Because the products we use to control these weeds are limited to the variety of turf grass we are growing, we must make absolutely sure we are using the correct products to kill the weeds we are trying to eliminate, while still keeping our lawns healthy. The key here is to identify the type of grass you are growing and then the weed you are trying to kill. I wish I could tell you there is just one product you need to kill all the weeds in your lawn with just one application, but that is not the case. Broadleaf weeds, weed grasses, and sedges all require specific herbicides. For those of you unfamiliar with these types of weeds, let me explain them to you.
Broadleaf weeds are weeds that look like weeds. They normally have a broad or wide leaf and a flower. An example of this would be a dandelion. Weed grasses are weeds that look like your grass, but no flowers. An example of a grassy weed would be Wild Bermuda (very common in St. Augustine Grass) or Carpet grass. Sedges are weeds that also look like grass but have a triangular stem and produce either a single nut or a group of nuts at the top of the weed. If you cannot identify either the type of lawn you have or the weed you are treating, then you should take a sample of both to your local Cooperative Extension Agent or send a good-quality photo attached to an e-mail to me for proper identification and control. Properly identifying your weed and applying the right control will save you money, time, and keep your lawn looking good.
Regardless of what type of weed I am treating for, I like to use liquid herbicides because I can place the product where the weeds are, and I do not have to treat the entire lawn and waste money with a granular product. Granular herbicides are effective, but I have found that if you are unfamiliar with the product you are applying, and you do not read the label, then the possibility of burning or killing your lawn increases. I cannot tell you how many people I have talked to who have killed their lawns using these granular products.
When liquid herbicides are sprayed on a weed, you get quicker control because you can coat the entire weed. Another benefit to liquid herbicides is that you can mix up fresh product each time you need to apply it. A quick note to all homeowners, weed control means killing 80-90% of the weeds in your lawn. If you think you can kill all the weeds in your lawn, then good luck! There is a half-a-ton of weed seeds for every acre of grass in the world. This means you will have your job cut out for you. Because most of our lawns in Central Florida are St. Augustine grasses, I will start here.
For broadleaf weeds in St. Augustine lawns, you will need to use the active ingredient Atrazine (semi-ok control) or Celsius (much better). Celsius may be harder to find, but if you are looking for results, then you need this product. Both of these products require the addition of a Non-Ionic surfactant for best control. You can find both of these at most garden centers. Unfortunately, weed grasses like wild Bermuda or Carpet grass have no control. If you had experienced a freeze or heavy frost in the last month or so, then you may have noticed large brown areas in your lawn. These areas are where the carpet grasses and wild Bermuda grass browned out. You noticed I said browned out, not died out. When the warm-weather returns, so will these invasive grasses, with a vengeance. The only ways to control these grassy weeds are to kill them off with round-up and dig them out. After, you can re-sod the areas with new grass. Do not plug the area, re-sod the area or the grass weeds will come right back.
Lawns that are watered frequently or areas that have high-water tables are plagued by sedges. For sedge control, there is finally some good news. For control of sedges in St. Augustine, Bahia, or Zoysia grasses, you only need one product called sedgehammer. Sedgehammer is an herbicide used to control primarily sedges, although you may get some broadleaf weed control benefits. Mix sedgehammer with water to kill Yellow or Purple Nut grass and Green Kylinga. You will need to add a Non-Ionic surfactant to the mixture to get the best results. Please, read the entire label on all products used for proper mixing and application information. Do not over apply these products. Invest in a measuring device that you can use for your garden needs only. A baker’s measuring spoon set will suffice.
For broadleaf weed control in Bahia, Bermuda, or Zoysia grasses I recommend a product called Trimec Classic. Trimec is a liquid herbicide that will control most of your broadleaf weeds in as little as seven to ten days after application. The addition of a surfactant is not necessary. The active ingredient in this product is 2-4 D and Dicamba. There are several products available at most garden centers which contain this active ingredient, so you do not have to find the brand name I mentioned above.
There are a few things you need to know when applying herbicides. The taller the weeds are, the faster the products you apply will work. If you treat your weeds just after the grass is cut, or if you mow your grass following application, then the effectiveness of the product will diminish. The same holds true if you get a rainstorm, or if you irrigate your lawn directly after you apply an herbicide. The length of time it takes for herbicides to work may vary, but do not be discouraged. Wait at least fifteen to twenty days, before making additional spot applications.
Sometimes, new weeds will grow in areas you have already treated, but this is normal. The new weeds you are seeing may have been covered by existing weeds or were possibly too small to see when you made your original application. Be patient. You will reduce the number of weeds you have over time. As I mentioned above, weed pressure can be especially heavy in lawns that are sparse or under fertilized. Try to be vigilante and you will get them under control. If you have a particular weed that just will not die, then you must have it identified and seek additional control measures.
Keeping your lawn free of weeds can be a lot of work, and some people may think that even a few weeds are too many. As new herbicides are introduced into the marketplace, optimum weed control is based on only eighty percent control. This means that there will always be weeds in every lawn so do not be discouraged if you have a few weeds here and there. Treat your weeds according to the directions I mentioned above. Do not be afraid to seek out help from others in identifying weeds you may be having problems with. Have fun in the garden and remember, without plants, we would not be here!