by Les Harrison | Mar 2, 2017
Photo caption: Purple nut sedge is dormant, but quite alive and waiting for warm weather. The best hope for control is to use a pre-emergent herbicide in late February to early March which will prevent this exotic invasive plant from germinating.
Now that March is here the lawn becomes less of an abstraction and more reality.
The lawnmower is no longer silent, meaninglessly taking up space as the grass wakens from its seasonal stupor. Alas, the dormant state has ended as the days are already getting slightly longer.
There is still time to get started with preparations for the ideal spring lawn of 2017. Weather is getting warmer, there is plenty to do.
In addition to doing a soil test, mentioned in previous week’s articles, an accurate weed assessment is also necessary. Though not green and conquering new territory, some of the weeds remain with seed still attached and awaiting distribution.
If the seed are still on the plants, clip the seed pods or remove the plants with the seed intact. Dispose of these properly and do not give them a chance to spread and germinate.
Two notable culprits are nondescript lying dormant waiting for the return of warm, sunny weather. Purple nut sedge and chamberbitter still have countless nutlets and seeds connected to the parent plant.
Purple nut sedge, Cyperus rotundus, grows from every possible sunny location with soil. This non-native plant is a rapidly spreading perennial which will take every opportunity to colonize new locations.
The identifier purple is in its name because there is a purple-tinged section of this sedge where it emerges from the ground. The plant is sometimes referred to as purple nut grass because of its long narrow leaves and its erect growth pattern originating from a nutlike basal bulb.
Chamberbitter, Phyllantus urinaria, is an annual with produces great quantities of seed on the underside of its leaf stems. It will handle full sun or partial shade and quickly form cluster of plants, each contribution seed to the soil.
Areas in the lawn identified as having severe infestations should be marked now for treatment in the near future with a pre-emergent herbicide. This type of herbicide prevents the seed from germinating in the spring.
Purple nut sedge concentrations should be sprayed in late February to early March, and chamberbitter in April since these pest species germinate at different times.
Another winter task is to prepare for seeding bare spots in the lawn. Reading the seed tag attached to the bag should help make the product selection much easier.
Check to confirm the seed has been tested for germination within the year. Also, be sure the grass seed species will grow in Florida.
Sometime generic lawn seed mixes will contain fescue, bluegrass, orchard grass and others turf types which will not grow in north Florida. While they may germinate, their use will only ensure weeds get established for another year.
Lastly, sharpen the lawnmower blade. When the warm weather arrives the mower will be frequently used, but at least the neighbors will be envious of the great green lawn.
by Julie McConnell | Feb 23, 2017
Regardless of what the tag says one size does not fit all. As with clothing, a piece will undoubtedly be too large for some and too small for others. Trying to go with a “one size fits all” approach to lawn care will lead to the same kind of frustration and disappointment as an ill-fitting garment.
All turfgrass is not created equal. Thus management of our various turf species requires different methods. It is common for a homeowner to be unaware of what type of turfgrass they have – it’s all grass after all – what difference does it make? Misidentification leads to problems because proper management for one type may be counterproductive to another type. In order to create a practical turf management plan, it is critical that the species of grass is properly identified.
Although many grasses look similar it is important to know exactly what kind you have to maintain it properly. This photo shows Empire Zoysia. Photo credit: Julie McConnell, UF/IFAS
Why is it important to know the species of turf in a lawn?
Two of the most common mistakes extension agents observe is excessively low mowing height of St. Augustinegrass and over-fertilizing Centipedegrass. Both of these errors can reduce turfgrass vigor and decrease its tolerance to pest issues. Another potential maintenance pitfall is using a herbicide that is not labeled for use on a given type of turfgrass. Several popular herbicides available on the market can cause damage to St. Augustinegrass and/or Centipedegrass. Thus turf can be inadvertently killed by herbicides when they are applied to the wrong species.
Before a lawn maintenance plan is developed, be sure to know what type of grass is present and then follow UF/IFAS recommendations for proper care. If assistance is needed with identification, contact your local extension office.
To learn more about lawn care, visit this site or plan to attend “Caring for Your Florida Lawn” at the UF/IFAS Extension Bay County office on April 8th. For more details call 850-784-6105.
by Sheila Dunning | Feb 3, 2017
Remember last summer? The hot, dry days. Grass drying up and turning brown. Yet, the weeds are green and doing fine. However, every herbicide label warns against applying when the temperatures are above 85 degrees and especially under drought conditions. Those weeds flourished and dispersed seed everywhere. Now, they are just sitting there ready to sprout again.
It’s time to start thinking about weed prevention. Pre-emergent herbicides need to be applied prior to seed germination. Late winter is the time to focus on summer annual weeds. The narrow window of application is challenging. Homeowners often wait too late into spring to put out preventative products. A general rule of thumb for pre-emergent herbicide timing is February 15 – March 1 in North Florida.
However, weed seeds germinate in response to soil temperature, not calendar dates. By monitoring day time temperatures, one can determine a more effective application date. When there are 4-5 consecutive days that reach 65 to 70 degrees weeds will germinate. This generally coincides with the first blooms appearing on azaleas and dogwood. With a warm winter it may occur as early as mid-January.
Some of the active ingredients in pre-emergent herbicides include dithiopyr, isoxaben, oryzalin, pendimethalin, prodiamine and simazine. Always read the label for specific weed controlled and observe all directions, restrictions and precautions.
Weed and feed products that contain nitrogen are not suitable as pre-emergent herbicides. Irrigation before and after application is necessary to activate these products. The chemical binds to soil particles, creating a barrier that remains effective for 6-12 weeks. Reapplication will be necessary for season long control, especially with constantly fluctuating winter temperatures. Now is the time to purchase pre-emergent herbicides and prepare to apply them. For more information on weed control in lawns go to: http://edis.ifas.ufl.edu/ep141
by Beth Bolles | Jan 17, 2017
It won’t be long before homeowners start thinking about sodding a new lawn or renovating areas of their existing turf. Although sodding when turf is dormant is acceptable, it is best to install sod that is green. One reason is that you can see if any sod pieces are infested with weeds such as bermudagrass . This perennial grass is very difficult to manage once it becomes established in centipede, St. Augustine, or zoysiagrass. Always remove turf pieces with bermudagrass during the installation process to prevent it from taking over a patch of your new lawn.
Bermudagrass growing in a piece of centipede sod. This piece should have been removed during installation to prevent the bermudagrass from taking over a patch of new centipede lawn. Photo by Beth Bolles, UFAS IFAS Escambia County Extension
If you have a piece of turf or a small area where common bermudagrass has emerged in your desirable grass, take care of the issue as soon as it is seen. The best option is dig out the infested area making sure that you get the underground runners of the bermudagrass. Smooth out the bare soil and then install new sod pieces. You may have to hand water these pieces as needed since the surrounding turf will already be established.
by Carrie Stevenson | Oct 12, 2016
Dr. Ramon Leon, Extension Weed Specialist, West Florida Research and Education Center
Herbicides simplify weed management by allowing you to cover extensive areas in a relatively short time, and reduce the need for time-consuming control practices such as hand weeding. Additionally, many herbicides have the advantage of selective control. Selective herbicides are those that kill weeds without significantly injuring the desired plant. In turfgrass, selective herbicides are particularly important because we do not have the option of using cultivation or non-selective herbicides, as is commonly done in other agricultural systems such as row crops and orchards.
A common misconception is that when a herbicide is registered for use on a given turfgrass species, this herbicide has little negative effect on the turf. In reality, even when the herbicide is registered for a specific turfgrass species, it can cause a certain level of injury. If the herbicide is applied at the recommended label rate, and the growing conditions are ideal, the turfgrass will only suffer minor, temporary injury that may go completely unnoticed. Conversely, the weeds that are susceptible to the herbicide will be severely affected resulting in the desired control.
Over the last few summers, there has been an increase in complaints about herbicide injury on sod farms, golf courses, and home lawns after applications of herbicides, especially during the summer months. Many of those complaints originated from situations in which the application was done properly, using the recommended label rate, and thus the level of injury observed was not justified. After studying all these cases, it was determined that at the time of herbicide application the turf was under a moderate level of stress, but not high enough stress to cause visible symptoms. However, when the herbicide was applied the combined effect of the existing stress, and the stress caused by the herbicide made it harder for the turf to maintain the desired quality. For example, Figure 1 below shows that the turf looked fine before the application (A), but after the herbicide was applied, there was a significant loss in turf cover and quality (B). The interesting aspect is that the injury was not present across the entire treated area, but only on patches (C). Those patches corresponded with sand pockets where soil moisture, especially on hot days, was considerably lower than the rest of the area. In that particular case, the irrigation system was providing enough water to help the turf tolerate the moderate stress of high temperatures and limited moisture, but not enough for the turf tolerate the combined stress that occurred after the herbicide was applied.
Figure 1. Centipedegrass growing during the summer in Florida before herbicide application (A), 3 weeks after herbicide (sulfentrazone and metsulfuron-methyl) application (B). Herbicide injury pattern with highlighted areas showing where sand pockets caused drought and heat stress that contributed to herbicide injury (C).
In Florida, there are a combination of environmental factors such as high temperatures and sandy soils that can create stressful conditions limiting turfgrass growth, especially when irrigation is not sufficient to keep the turf hydrated. Furthermore, we also experience periods of excess rainfall, and areas of turf growing under shade. Additionally, pest problems that affect roots and leaves are frequently found in our state. All these conditions affect turfgrass health and its ability to tolerate herbicide applications. For these reasons, turf producers and managers need to be proactive to help turfgrass overcome the injury that herbicides might cause. To achieve this goal, you need to follow five simple steps:
1) Identify weed problems early. Most weed problems will start in the spring for summer weeds and in the fall for winter weeds. Controlling them when they are small not only increases the effectiveness of our applications, but also allows us to implement our control when the turfgrass is less likely to be stressed.
If herbicide applications are needed when conditions might be stressful for the turf (high temperatures and/or dry conditions)
2) Make sure irrigation is adequate (increase frequency or duration if needed) for up to three weeks following application.
3) Reduce mowing frequency and increase mowing height 0.5 inches for up to 3 weeks following a herbicide application, to allow the turfgrass to continue producing energy to support its recovery. Mowing too short and too frequently immediately after the application weakens the turfgrass.
4) Fertilize with a small amount of nitrogen (0.25 to 0.5 lb N/acre) a week or two after herbicide application to help the turf recover and produce new leaves.
5) If the turfgrass is suffering from serious pest problems (pathogens, nematodes or insect infestations) do not apply herbicides on the affected areas until the turfgrass has recovered.
Maintaining optimal turfgrass growth is the best way to ensure that herbicide applications will maximize weed control while still protecting the health and aesthetics of your turfgrass.
For more information on growing turfgrass in Florida, please see the following:
Dr. Ramon Leon, Extension Weed Specialist, West Florida Research and Education Center
