Skip to main content

Weed Management in Lawns

In weeks to come we will experience  Increased temperature which will  accompany by increase weed pressure in our landscapes. In the past week or so, UF/IFAS Extension in Osceola County is getting many questions on weeds. Questions include; when should I apply pre-emergent herbicides, what is the best herbicides to kill broadleaf weeds and how to get rid of grassy weeds in St. Augustine. Some of the reasons we strive to have a so called weed free lawn are: weeds are very unsightly, compete with desired plants for water, sunlight, and nutrients.

How to prevent weeds: When establishing a new lawn, it is important to kill all existing weeds before tilling the soil, sowing seeds, or laying sod. Existing weeds that are not properly controlled will emerge very quickly.  Purchase seeds only from reputable dealers.  Seeds that are not from a good source are often infested with weed seeds. The first step to a good weed management program is applying a good pre-emergent herbicide at the right rate and time. As you all heard it, prevention is better than cure. A good pre-emergence program will reduce or eliminate the need for post-emergent herbicides. Do not forget to apply about ¼ inch of irrigation after pre-emergence is applied.  It is also important to note that weed population is influenced by irrigation, therefore know how much and when to irrigate. Too much water will lead to a weed infestation.

How to control weeds accurately: To accurately control weeds, you first need to identify the weed correctly. Some people make the common mistake of believing that one single non-selective herbicide will control all weeds. In addition, not all pesticides are labelled for use on all species of turf. Mix herbicides per the instructions on the label; more is not always better when it comes to herbicides. It is advisable to start with the lowest recommended rate. It is possible for turf to become injured after application even though the recommend rate is followed; for instance, if herbicide is applied at temperatures over 90 degrees. It is important to carefully read the label for listing of weeds, turf type, rate, and environmental conditions. A smart person said that we should read the label at least four times; before purchasing, before mixing, before application, and before storage.

Rotating herbicides will decrease the likelihood of herbicide resistance. Rotating herbicides does not mean changing names of herbicides. When rotating herbicides, be certain that herbicides do not have the same active ingredients and that they have different mode of actions. Remember that we are all striving to becoming good environmental stewards so avoid applying herbicides if rain is expected within 24 hours. For more information related to landscape and ornamentals, contact Grantly Ricketts, UF/IFAS Extension Commercial Agent in Osceola County at 321-697-3000 or gricketts@ufl.edu.

Leave a Reply

Your email address will not be published. Required fields are marked *