There are certain weeds that grow in the winter and other weeds that grow in the summer. Because different weeds appear in our lawns during both of those seasons, it’s important to spray in both spring and fall. However, there are even more good reasons to spray pre-emergents more than just once a year: doing so allows for strategy, environmental stewardship, and root development in our turfgrasses.
Different Weeds Grow in Different Seasons
Weeds are simply plants out of place. They may have a use somewhere, but we don’t want them in our yards. Each species of plant is divided into a number of broad categories, including cool season and warm season. That goes for weeds, too.
In the Atlanta area, you can find these weeds:
- Warm season weeds: grasses such as crabgrass and goosegrass. Warm season broadleaf weeds include spurge and doveweed.
- Cool season weeds: grasses such as Poa annua, roughstalk bluegrass, and fescue clumps. Cool season broadleaves include henbit, Carolina geranium, and oxalis.
Warm season weeds begin growing from seed in the spring as soil temperatures rise. Cool season weeds do the same, but they wait for soil temperatures to drop in fall. Timing the application of pre-emergents before the seeds germinate is important to ensure they don’t develop roots, thwarting their development from the start. While it may seem cool to have a product you can apply once a year, there are advantages to separating them.
Top 3 Benefits to Applying Spring and Fall Pre-Emergents
1. Using the Same Product Repeatedly Breeds Immune Weeds.
Plants are fascinating. While two plants of the same species may look the same on the outside, they can have genetic differences we can’t see. There is always the chance that an individual weed may not be hurt by a weed control product. Exclusively using a single pre-emergent results in resistant weed populations. By strategically using different products and combinations, we protect and prolong their effectiveness.
2. Strategic Planning Can Yield Maximal Results.
Whether because of acquired resistance or a natural predisposition to resist symptoms from certain modes, multiple applications per year allows for the strategic use of certain active ingredients and modes of action that are most effective on the weeds likely to present themselves in a season.
3. Shorter Durations Are More Environmentally Friendly and Better for Turf Health.
Pre-emergent weed control products, like all pesticides, are heavily regulated by the EPA. It’s illegal to apply a pesticide outside of the constraints present in the label. One of the key factors the EPA considers when issuing a label and registration number for a product is its environmental impact and the length of time it will exist in the environment. Products with a less significant duration are often better for the environment.
Beyond duration in the environment, having a period of time where pre-emergents aren’t at full strength is a nice window of time where our turfgrasses can produce even more root mass, strengthening their heath and hardiness.
Some Weeds Are Just a Pain
Even the best-laid pre-emergent plans can be challenged.
- Established perennial weeds have root systems, so controlling them with pre-emergents isn’t possible.
- Some weeds germinate late, after pre-emergents have begun degrading.
- Certain areas in yards are more susceptible to breakthrough than others, and this is all okay.
We work in the environment, as do our products. Every good weed control program uses quality post-emergents, and we’re happy to apply them where necessary.
If our turf professionals at Nature’s Turf can answer any more questions about the ways we combine our knowledge and experience to get the most out of your weed control, give us a call at 770-461-4156, or email us at info@naturesturf.com. We’d love to discuss the many ways we destroy weeds and defend lawns.
