Weather is inconsistent; crabgrass, nutsedge, and brown patch can be counted on.
With last year’s employment and supply chain issues, the usual technical challenges, like hard-to-control weeds and diseases, did not go away. Looking back on 2021 from Weed Man’s national perspective of franchises across North America, there were plenty of challenging turfgrass issues. Remembering these challenges can help us be on the lookout and prepared for what 2022 may have in store.
A big part of the challenge when it comes to weeds and disease is related to weather—and unfortunately, we have no control over this major factor. 2021 was a year of weather extremes from record-shattering heat to frigid cold waves, torrential downpours to relentless drought. Weather plays a major role in the amount of weeds as well as the types and severity of diseases. But it also has major implications on efficacy of treatment applications.
For example, in mid-February 2021, a historic cold wave crippled the Central U.S. It was especially disruptive to the weed applications already started, from Texas all along the Gulf States. Cold weather can make weed control difficult and slow down weed death; not to mention concerns for equipment freezing.
In early summer, the Central U.S. again saw several severe weather systems, producing significant thunderstorms and some hail. These storms were particularly hard on pre-emergent controls as heavy rain can reduce effectiveness. These storms also brought adult army worms which created major issues later in the season.
The East and Southeast, in March and May, had several severe weather events such as tornadoes and thunderstorms. Again, these storms and their timing can affect grassy weed pre-emergent applications, as well as broadleaf weed control.
In the Northwest, we continued to see extreme drought and record breaking temperatures. Portland, OR, and Seattle, WA both shattered high records, reaching 116˚ and 108˚, respectively. But the Northwest wasn’t alone. The average temperature for the continental U.S. was 74˚ last summer, making it one of the hottest on record. (Tying the 1936 Dust Bowl summer.) Extreme heat and drought conditions make it very difficult to get good control on summer weeds. They harden off and herbicides do not work as well.
To top it off, two major hurricanes and two tropical storms wreaked havoc from July to September. What a season!
Right now is the perfect time to review last year’s successes and challenges and consider what can be done to enhance lawn care programs for 2022. A “normal” season would be great. Yet despite being involved in lawn care for as long as I’ve been, I’m still not sure what a “normal” season truly looks like. No doubt, there will be regional issues. But for the past few years there has consistently been two major weed issues we’ve battled pretty much everywhere: crabgrass and nutsedge. And on the disease front, brown patch is always a concern.
Crabgrass control has always been an issue of proper application mixed with proper timing of the pre-emergent applications. When it comes to pre-emergent herbicides, whether you use Dithopyr or Prodiamine, the two most important things to remember are 1) timing of application and 2) applying the proper amount of active ingredient to prevent germination in late summer. This must also be done cost efficiently, since you likely don’t have an unlimited budget for pre-emergent.
One thing that can affect the timing of pre-emergent applications is soil temperature, since it’s an important aspect of weed germination. Where you’re located will dictate timing. Obviously, the further South, the earlier you will need to get the pre-emergent on the lawn. It may even take multiple applications.
Also, it’s important to remember the environmental factors that break down herbicide, especially wet springs. Too much rainfall, or even not enough, can either break the herbicide’s barrier down more quickly than expected or slow down activation, allowing time for weed seeds to germinate.
Remember that pre-emergent herbicides must be watered in after applying to create the barrier that prevents germination. It’s critical to success. This should be done at least seven days prior to the initial germination date to allow time for the herbicide barrier to be established in the soil. Keep in mind that pre-emergent herbicides don’t destroy weeds or seeds. They simply stop them from growing.
If weather or application issues degrade treatments and you have crabgrass breakthrough, there are still plenty of options you can use to treat post-emergently. A new option for 2022 that Weed Man is using is Quintessential from Prime Source. The active ingredient Quinclorac in this product is powered by H-Value Technology, a proprietary performance additive that improves absorption of the herbicide into the plant.
The other troublesome weed invading home lawns is nutsedge. Nutsedge is very difficult to control because it spreads by seeds and underground rhizomes, but its primary route for turf takeovers is underground tubers, known as nutlets. Nutlets store energy reserves and bear buds, sort of like a potato, and it will send up sprouts to form new plants. Penn State Extension reports that one-years’ worth of rhizome growth from a single nutsedge tuber can produce 1,900 plants with 7,000 new tubers. A single plant can produce 90,000 seeds in one season!
The best you can hope for when dealing with nutsedge is to limit it as much as possible. Unfortunately, total eradication is not likely achievable. Late last year, Bayer brought its new Celsius formulation to the market called Celsius XTRA, that now has the added control of sedges. It also offers turf safety on warm season species, including sensitive varieties like St. Augustinegrass and centipedegrass.
Once again a major concern for turfgrass health is dealing with brown patch disease. Last Spring, many regions saw higher rain than normal, coupled with above average temperatures during the day and unexpectedly below average temperatures at night. While this slowed down greening up, the real concern was that these conditions created the perfect storm for brown patch.
Large patch or brown patch, which is caused by Rhizoctonia solani, is the most common disease of warm season turfgrasses. As the name suggests, when conditions are favorable the disease develops rapidly into large circular or irregularly shaped patches of brown turf. Although the turf is usually not killed, it does attack and rot the bases of the leaf sheaths, killing the leaf blades. This results in areas of sparse turf that are readily invaded by weeds, which creates another problem requiring additional management.
Brown patch development is favored by frequent or prolonged periods of rainfall when temperatures are moderate. Although we typically think of brown patch as a Fall disease, it can develop in the Spring, especially with prolonged periods of cool nights, warm days, and wet weather after green-up.
Obvious controls like fungicide/disease treatments can be applied. However, timing of applications is extremely important and last year, due to the weather conditions, many applications likely came too late.
One not-so-obvious treatment is proper fertilizer application. There has always been a belief that brown patch is a disease of over-fertilizing, yet research coming out of the University of Nebraska-Lincoln and North Carolina State provides new perspective. The research shows that under-fertilized turf in the summer experiences an increase in brown patch, compared to those with regular fertilizer applications. Certainly, the biggest factor is the use of slow-release fertilizer in prevention.
Since brown patch is a root or soil disease, proper placement of the fungicide (getting it where the issue is) will determine performance. Using a high volume of water is important. Adding in a penetrant will also help promote water infiltration and works best with systemic fungicides that target root- and soil-borne diseases.
The usual technical challenges of this industry are inevitable; hard-to-control weeds and lawn diseases aren’t going anywhere. But, as we head into a new season, preparation and knowledge are your best defenses.
Lemcke is the national technical director at Weed Man Lawn Care. He has been a part of the company for nearly three decades, from having worked in operations out on the lawn to helping spearhead the brand in the U.S. alongside the rest of the Turf Holdings Inc. team and dedicated sub-franchisors. Now, Lemcke handles the technical department from a head office perspective, supporting franchisees across North America, ensuring they are using the best products and equipment out on the lawn, and providing knowledge on all things ‘agronomics.’
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Nutsedge sometime can also controlled by a post-emergent herbicide. Most control products take about 10-14 days
Nutsedge some time can also controlled by a post-emergent herbicide. Most control products take about 10-14 days
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