The lawn is a source of pride for most and anything out of the ordinary causes alarm. Now image finding something that looks like lumpy green jelly in your turfgrass and it doesn’t go away. You try raking it, spraying it, covering it, and it still comes back time and time again. One of the things we see in late spring/early summer turf is a reemergence of cyanobacteria (Nostoc), sometimes confused with algae because of green coloring and this remains all summer long.
Dehydrated cyanobacteria in a centipedegrass lawn.
Unlike normal bacteria that needs a food source, cyanobacteria contains chlorophyll and produces its own food source through photosynthesis which allows it to grow on bare sandy soils, fabric mats, concrete sidewalks, plastic, and yes even your lawn. Besides the green pigment, it also produces a blue pigment and is why we call it cyanobacteria which means blue-green bacteria. In addition to photosynthesis, cyanobacteria can also fix nitrogen, and are believed to produce cyanotoxins and allelopathic compounds which can affect plant growth around them.
Cyanobacteria are considered one of earth’s oldest organism and they have tremendous survival capabilities. They can dry out completely, be flat, flaky, black-green dried particles in your lawn and once rehydrated, spring back to life. If you happen to notice it spreading throughout your yard, remember that pieces of the organism can stick to your wet shoes or lawnmower tires and be transported unintentionally.
The question then becomes how to control the cyanobacteria and reclaim your turfgrass. The first solution is to have a healthy lawn. Cyanobacteria likes poorly-drained compacted soils. This same condition is unfavorable to turf growth and why you end up with bare spots and establishment. Reduce soil compaction by using a core aerator, and then adding organic matter. This will increase drainage, gas exchange, and encourage microorganism populations which I like to call soil pets. Spike aerators only push the soil particles aside and don’t really loosen as well. Try to reduce low lying areas in the lawn where water sits after rainfall and irrigation. You might have to till and reestablish those areas of the yard.
The same cyanobacteria pictured above 24 hours after being rehydrated in a petri dish of standing water.
Controlling the amount of water Mother Nature gives us and humidity levels during summer is not possible, but you can control your irrigation whether it be automatic (sprinkler system) or hand-watered. During the rainy season, you should be able to get by with only rainfall and shut off your system. If needed during extended dry weeks, it is easy enough to turn the system back on. It is thought that cyanobacteria likes phosphorus which is another reason to use little to no phosphorus in your lawn fertilizers.
As you begin to rid your lawn of cyanobacteria, remember when fully hydrated it forms a slippery surface so be careful walking on it. Cultural practices will be more effective in controlling the spread versus using chemical methods. Cultural solutions are safer for your lawn, yard and all of the wildlife that visits. If you need help with your cyanobacteria, please contact your local Extension office and we are always happy to assist.
A special thanks to Dr. Bryan Unruh, UF/IFAS for his assistance in identifying the cyanobacteria.
For additional information, please read the sources listed below.
We work very hard to maintain our gardens and then we look up and vines are growing 20′ into the trees. I get asked frequently “what is growing up my trees?” My first answer is “probably the same things growing on your fences.” These include Smilax species, commonly called catbrier or greenbrier, Vitis rotundifolia, referred to as wild muscadine grape, Parthenocissus quinquefolia or Virginia Creeper, and the one to be most careful with, Toxicodendron radicans, known by many as Poison Ivy.
Spring growth on the Smilax vine.
Smilax is a native vine that grows quickly in spring and all summer. There are 12 species in Florida and 9 species commonly found in the Panhandle. Besides being armed with thorns on their stems and some leaves, Smilax spreads by underground stems called rhizomes. If you choose to ignore it, some species can cover your trees and the stems become woody and hard to remove. This vine also produces fruit and seeds are dispersed by birds all while the underground rhizomes are spreading under your lawns and gardens.
Smilax can quickly cover a tree trunk.
Removal can be difficult and mowing the vines only encourages more growth. When trying to remove by hand, wear heavy leather gloves and some eye protection because of the thorns. Cut the stems about three feet above the ground which allows you some stem to pull on to bring it out of your tree. You also then have a handle to pull and try to remove some of the rhizome from underground. Digging rhizomes is time consuming, but gives you piece of mind that they won’t come back immediately. Our family actually harvests the new shoots in spring and we use them like asparagus.
Wild muscadine grape is also native and difficult to remove. Most of the vines in nature are male and only produce by runners along the ground and then grow upwards. The female vine can produce 4-10 grapes in a cluster and then reseeds itself.
Wild muscadine grape covering a fence.
Wild grape completely covers plants and eventually the plants underneath can die. There are no thorns to contend with when removing wild grape, it is just time consuming, especially if it has taken over your fence or natural areas.
Virginia Creeper is a native vine, still considered a nursery plant in some areas of the country, and has bright red fall color.
Virginia Creeper climbing a tree trunk.
It is most often confused with poison ivy because of having five leaflets per leaf whereas poison ivy only has three leaflets per leaf. It spreads by seeds, runs along the ground, and is the easiest of these four vines to remove from your property.
Poison Ivy is a native vine distinguished by its three leaflets with the individual leaflets getting up to 6″ long. This vine spreads by seeds and underground rhizomes. What makes removal of this vine difficult is the urushiol oils which causes the skin rashes and blistering.
Poison ivy covering a tree trunk.
Care must be taken to cover up all skin and I recommend wearing waterproof clothes versus cotton which can absorb the oils and transfer them to your skin. Under no circumstances should these vines be put on the burn pile, the oils can become airborne and then you can inhale them.
Here are a few helpful tips when battling these native vines. First have patience and be dedicated, this removal will not happen over night. It may take a year or two to rid your property of the original vines. Be diligent though, because birds will continually land in your trees and deposit more seeds to get a fresh start. Try to remove vines when they are young and just beginning to climb your trees and fences. If you know you don’t have the time or energy to remove the vines from all your trees, at least cut the vines close to the ground to reduce flowering and new seeds. Be careful with poison ivy because falling leaves still contain oils. Once the vines start to have a new flush of growth, spray a non-selective herbicide on new growth and you should have good results. Lastly, remember one person can make a difference in trying to reduce the number of nuisance vines in our communities.
As a boy in a small town in Georgia we had a St. Augustinegrass lawn. My dad started the lawn before I was born. That lawn was still doing fine when I left for college at age seventeen. I don’t remember weeds in the lawn during summer months. I do fondly remember winter “weeds” in that lawn.
To see clumps of winter annuals in our yard and in neighbors’ yards was a natural part of the transition from winter to spring. They added interest to what
Blue Easter egg hidden in chickweed. Photo credit: Larry Williams
would have been a plain palette of green. It was expected to see henbit with its square stiff stems holding up a display of small pinkish purple flowers in late winter and early spring. A clump of henbit was a great place to hide an Easter egg, especially a pink or purple one.
Wild geranium, another common winter annual, offered another good hiding place for Easter eggs with its pink to purple flowers. Large clumps of annual chickweed would nicely hide whole eggs. Green colored eggs would blend with chickweed’s green leaves.
Pink Easter egg hidden in crimson clover & hop clover mix. Photo credit: Larry Williams
Crimson clover with its reddish flowers, hop clover and black medic with their bright yellow flowers were good hiding places for Easter eggs. Plus clovers add nitrogen back to our soils.
I never remember my dad using any weed killer, he rarely watered. The lawn was healthy and thick enough to be a deterrent to summer weeds. But during fall and winter as the lawn would naturally thin and go dormant, winter annual weeds would run their course.
I’ve heard that the sense of smell provides our strongest memories. I remember the first mowing of the season with the clean smell of chlorophyll in the spring air. It was refreshing. Once mowed and as the heat took its toll, by late April or mid-May, these winter annual weeds were gone. What was left was a green lawn to help cool the landscape as the weather warmed. The lawn was mowed high as St. Augustine should be, played on and typically not worried with.
Most people have winter weeds in their lawns that let us know spring is near. Perhaps we worry too much with these seasonal, temporary plants that may have wrongly been labeled as weeds. Besides, how long have we been doing battle with these weeds and they are still here. Most lawns have countless numbers of winter annual seeds awaiting the cooler temperatures and shorter days of early winter to begin yet another generation. By May they are gone.
Earlier this summer I talked about getting to know your weeds, so they’ll be easier to control. If you missed that article you can review it here “Why Can’t I Kill Weeds?”
Today we will look at the types of herbicides available so your selection will fit your situation.
Understand your herbicide options. Picking out the appropriate herbicide can be overwhelming. The options seem unlimited when you are standing in the store looking at aisles of containers. By preparing yourself before you shop you can save time and increase your chances of making the most effective selection. Here are some herbicide basics:
Label interpretation. The pesticide label is a multipage document that describes ingredients, how a pesticide works, application instructions, safety requirements, and other important information for the user. Before applying any pesticide (yes, herbicides are pesticides!) you should read the entire label. Pulling the label off the package in the store may be frowned upon and the print is very small. For this reason, I would recommend looking up a few options before you go shopping and reading the labels online. This allows you to take your time to be sure you understand if it is the appropriate product and you can make your shopping list for personal protective and application equipment before you leave the house. Three important things to look for when selecting your product are active ingredient, labeled site (site includes the location such as residential landscape vs. agricultural crops and the plants it is safe to use on), and targeted pest.
Non-selective, systemic herbicide damage on grass. Photo: J_McConnell, UF/IFAS
Pre-emergent herbicides. Pre-emergent herbicides provide control when applied BEFORE seed germination of your target weed. They do not prevent germination, rather they prevent emergence of shoots and roots essentially inhibiting normal plant growth which eventually results in plant death. It is important to have your product in place during the correct window of time. Typically, 1-2 weeks before germination of your target weed is ideal.
For warm season annual weeds (crabgrass, goosegrass, sandspur, and spurge are examples) apply pre-emergent herbicides when day temperatures in early spring reach 65-70°F for 4-5 consecutive days. This may be mid-February or as early as January.
For winter annual weeds (henbit, black medic, geranium, and chickweed are examples) watch for night temperatures in the Fall to reach 55-60°F for several nights in a row to indicate proper application timing.
Some products are selective to plant types such as grasses, sedges or broadleaf weeds. Other products are more broad-spectrum and are effective on multiple weed types.
Pre-emergent herbicide should not be used if you intend to plant seed – it will affect your desired plant in addition to the weed! There may also be effects on newly planted lawns or plants, so be sure to read the label closely to avoid damage to non-target plants.
Post-emergent herbicides. These products are used on weeds that have already emerged, regardless of life cycle (annual, perennial, biennial). This type of herbicide will be applied directly to the weed you are trying to kill. There are a few categories within this group.
Selective or non-selective.
Selective herbicides work on particular categories of plants: broadleaf, sedge, grass, or woody plant.
Non-selective herbicides can kill any type of plant regardless of category.
Contact or systemic. Contact herbicides kill the plant tissue it comes into contact with and does not translocate to the rest of the plant.
Systemic herbicides are translocated throughout the plant to affect more than just the place of absorption. These are ideal for perennial weeds that would regenerate from roots, bulbs, or tubers if the top is damaged or killed.
Effective weed management requires some preparation and research for the best outcome. For help with weed identification and control recommendations, contact your local UF/IFAS Extension Office.
Pesticide labels are not exciting reading materials but they contain necessary details about the specific product. The label information helps you with many decisions to use the product correctly and protect yourself and the environment during the product use. Beth Bolles with UF IFAS Extension in Escambia County will share information about a readily available product and why you should always read through the complete pesticide label.
