Every homeowner, no matter who they are, hates weeds. They pop up overnight and take over your lawn – broadleaf weeds, grassy weeds, crabgrass, dandelions, and clover everywhere. If you’re not taking proactive steps to prevent weeds from infesting your lawn, including year-round weed control, then you’re not going to make the most of your home.
Weeds are any type of plant growth that is unwanted, unsightly, and annoying to a property owner. Some weeds get crowded out by thick turf. Others are killed off with a simple mowing of the lawn. Most weeds, however, are perfectly capable of taking up residence on your lawn and will replicate like a virus until they are taken care of with weed control or the season passes. Because there are hundreds of different kinds of weeds, with different biological structures and considerations, modern weed control programs must use a spectrum of different products to get the job done right. Weeds are sort of like cancer in the yard. There are hundreds of different kinds that are continuously evolving, keeping herbicide manufacturers on their toes trying to make herbicides that are safe and effective to use.
In many states, weed control is considered to be a form of pest control. Licensing for lawn care companies sometimes gets inter-mingled with licensing for pest control companies. Licensing is essential as the only way to get commercial grade weed control products is by passing a test that ensures the lawn care provider knows what they’re doing. Without these commercial grade weed and disease control products, a lawn care service simply won’t be able to get the job done nearly as well as a licensed provider.
Weed Control History
Research about the first weed control products, known as herbicides, began in the early 1900s with the first scientific breakthroughs coming in the 1940s. Imperial Chemicals developed the first herbicide known as 2,4-D for use in agricultural products in 1946 that enabled farmers around the world to yield more than ever from their properties.
In the 1950s, scientists discovered triazine herbicides, which were followed up in the 1970s with the discovery and introduction of glyphosate herbicides. Today scientists around the world are working hard to find the weed control holy grail, but Mother Nature always seems to win this battle with weeds constantly evolving so no one product will do.
The EPA thoroughly tests herbicides before they are approved for use in the United States. Most developed-world countries have governing bodies that oversee weed and pest control products being sold to the public or used by service providers. The EPA also has to monitor herbicides being brought into the United States to ensure there isn’t any horseplay going on. The EPA is known to play it safe when it comes to herbicides by only approving chemicals with an acceptable daily intake (ADI) level 100X lower than any dose level that showed toxicity. The EPA knows that these weed control products will be used on millions of acres of lawns, and they take their job very seriously, protecting people and the environment.
There are hundreds of broadleaf weeds in the United States. Because of their biological uniqueness compared to common grasses like fescue, Bermuda, and zoysia, weed control manufacturers have had great success bringing to market products that kill a wide spectrum of broadleaf weeds. The best way to deal with broadleaf weeds is by using a combination of pre and post-emergent weed control products throughout the year. What to use and when to deploy it depends on the area of the country you live and the type of grass you have. Service providers typically like to use at least a treatment or two of pre-emergent weed control products in the spring and then another in the fall.
Grassy Weeds & Sedges
One of the problematic issues property owners face is dealing with grassy weeds like crabgrass or nutsedge invading their lawns. Because grassy weeds and sedges are biologically similar to common grass types like fescue, Bermuda, and zoysia, they are usually much harder to deal with than broadleaf weeds. The key to keeping grassy weeds off your lawn is by doing year-round weed control, using pre-emergent weed control products, and knowing which selective herbicides to use depending on the grassy weed you’re dealing with. All of this is a lot to handle for the average homeowner, who isn’t even able to purchase many of the weed control products needed to tackle this challenge effectively because they are not licensed to buy them.
Pre-Emergent Weed Control
In most parts of the country, and on most lawn types, using pre-emergents is a critical component of a good, well-rounded weed control plan. The type of pre-emergent used depends on grass type, the state you live in, time of year, and environmental conditions. On most warm-season turf, you will see lawn care companies deploy 1-3 pre-emergent applications in the spring and then another critical one in the fall. The one in the fall on warm-season turf is vital because it defends dormant lawns from being invaded with cool-season grassy weeds. Cool-season grasses also usually get treated with pre-emergent applications depending on the state you live in.
Post Emergent Weed Control
After weeds have already taken hold of your lawn, a post-emergent herbicide will be needed to treat your lawn and to kill the weeds. Depending on how bad the weed situation is, it can take many treatments to make real progress. Lawn care services usually break their weed control treatments into two groups, one for warm-season grasses and another for cool-season grass. This is why you often see weed control companies with two big tanks of chemicals on the back of their trucks.
The key to post-emergent weed control is consistency and mixing the products up from time to time. There are hundreds of different kinds of weeds that lawn care services need to kill, so they usually use broad-spectrum post-emergent weed control products that can often kill 100-200+ weed varieties at a time. The tactics they use will depend on the state you live in, the grass you have, and any environment concerns they might identify.
Modern Lawn Treatment Plans
Throughout the United States, you will find that most lawn treatment services provide year-round weed control programs for the customers. Most lawn care providers use a combination of broad-spectrum pre and post-emergent weed control products throughout the year to kill and defend the lawns they manage from hundreds of broadleaf and grassy weeds. Weeds that have become immune to common broad-spectrum weed control products, including many grassy weed varieties, are usually treated with selective herbicide applications. These higher-cost applications target certain weeds or weed groups that often evade broad-spectrum products. What a lawn care service use depends on the state you live in, the grass you have, the time of year, and a variety of environmental concerns. For the most part, weed control and fertilization services provide excellent value for their customers as it’s often very time consuming, costly, and confusing trying to figure out what to put out on your lawn. Leave it to the experts might be the best piece of advice a homeowner can get!
Mechanism of Action
Here is a list of the most common mechanisms of action found in herbicides. Scientists are hard at work in laboratories around the world trying to tap into special genes and biological processes that weeds exhibit so they can create the next generation of pre and post-emergent weed control products.
ACCase Inhibitors – they impair cell membrane growth in weeds.
ALS Inhibitors – they inhibit DNA synthesis by inhibiting acetolactate synthase (ALS), which is needed in the synthesis of amino acids. This causes weeds to starve to death.
EPSPS Inhibitors – ESSPS is needed for the synthesis of several amino acids. EPSPS inhibitors block this process, causing weeds to starve to death.
HPPD Inhibitors – HPPD, otherwise known as 4-Hydroxyphenylpyruvate, is needed for tyrosine breakdown. Tyrosine breakdown byproducts are used by weeds to make carotenoids that protect chlorophyll from being destroyed by sunlight. HPPD inhibitors ultimately block chlorophyll in weeds via a biological interruption, and they die.
Photosystem I Inhibitors – they steal electrons from a normal cellular pathway, which leads to oxidative reactions weeds cannot handle, and they die.
Photosystem II Inhibitors – they reduce the flow of electrons from water to NADP+ during photosynthesis. This biological interruption causes a buildup of electrons in chlorophyll, which causes weeds to die.
Weed Control Classification
Contact Herbicides – these are herbicides that kill specific visible plant parts that they touch, without being taken up through the soil by surrounding crops or lawn.
Systemic Herbicides – these are herbicides that are absorbed into the weed/plant and move throughout the weed/plant. Absorption happens through the leaves or grass blades targeted with the treatment. The controversial weed killer glyphosate is the most popular systemic herbicide used around the world.
Soil-borne Herbicide – these are herbicides taken up through the soil by the roots of the targeted weed/plant.
Herbicide resistance is an emerging concern across the world. It’s an issue for homeowners who want their lawns to look immaculate, but it’s an even bigger problem for farmers and agricultural companies. When the owners/operators of lawn care companies are licensed to provide commercial-grade weed control services, they are usually taught about herbicide resistance in their state, state protocols around the subject, and what to look for.
Non-Target Site Resistance – weeds can form non-target site resistance by evolving to rid chemicals from their system before they reach their target site.
Target Site Resistance – this form of resistance develops when target sites within the biological function of weeds no longer allow weed control products to bind to a protein or interfere with electron transport.
Cross Resistance – this is when a single biological function in weeds evolves to prevent more than one herbicide type from doing its job.
Multiple Resistance – this is when weeds develop more than one resistance mechanism against herbicides.
Herbicide Group Labeling Project
The amount of herbicides used across the world is enormous, and the last thing you want happening is to have large population groups deploying the wrong herbicides, on the wrong plants or lawns, at the wrong time of the year. When you factor in that there are hundreds of different grass types, crops, and plants that need protection from hundreds of different weeds, it’s easy to see how lawn care services and farmers could become overwhelmed and confused by all the information.
To solve this, the Weed Science Society of America (WSSA) and the Herbicide Resistance Action Committee (HRAC) joined forces to create a ‘Group Labeling System” so that farmers, lawn care services, and homeowners can easily understand the mode of action and plants it works on. This was done to create order and simplicity for farmers, lawn care companies, and other users of herbicides. It will help them remember what they’ve used, what works and doesn’t, and helps to clear up confusion in the industry. These labels are found on the packaging/bottles of weed control products.
Ripping Weeds Out by Hand
It’s easy to go out there and pull a broadleaf weed out by hand, but the roots can break off in the grass, sprouting even more troublesome plants. On top of that, pulling out weeds by hand often leaves the root system of weeds intact, causing them to return a short time later.
Taking a calculated approach (like spraying the roots directly with herbicide) makes sure that you eliminate the weed without proliferating seeds for another generation to germinate. Luckily, some weed control sprays are labeled “safe for lawns,” which means you can spray weeds without harming surrounding grass.
Do-it-Yourself Weed Control Tips
Do Research – If you want to provide weed control yourself, make sure you read up well on all the products available to you, usually at a hardware store or online. Be sure the product explicitly states that it is safe for your grass type and follow the directions carefully.
Thicken Your Lawn – a thick lawn can crowd out and prevent the proliferation of weeds. This is especially true in turf grasses such as Bermuda and zoysia. Proper fertilization, mowing, and general lawn maintenance is needed.
Be Consistent – If you are a homeowner trying to do it yourself, then consistency is key. Plan to fight weeds every season. It’s a good idea to keep a bottle of broad-spectrum herbicide available so you can knock out weeds as you see them come in.
Overseed Fescue in the Fall – it’s a good idea to seed fescue every fall to thicken the lawn and to help prevent weeds from taking us residence.
Pest Control Applications – be careful when applying pesticides to avoid shocking the lawn or soil ecosystem.
Hire a Lawn Service – Ok, we admit it, we are biased, but we still think that most homeowners benefit significantly from hiring a licensed lawn service that offers a year-round weed control program. In most states, there are products that only licensed providers can purchase and apply that are essential for a comprehensive weed control program. For homeowners, it takes a lot of work, and it becomes very costly to apply 6-10 lawn treatments themselves every year, so there is a lot of value a lawn service can provide.