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Category: Cultural Practices

Nonchemical Weed Control Methods for Landscape Beds

Posted on by Brooke Garcia

By Dr. Cheryl Boyer

Dr. Chris Marble at the University of Florida is a weed management whiz. He’s a machine with research and writing and a kind friend and teammate of mine from graduate school at Auburn University. Naturally, I’m pretty excited and proud to see a paper he has authored published. I’m going to kick off my series of posts for the K-State Turf and Landscape Blog by reviewing some of his journal articles with clarity on which practices apply to Kansas and which may not (since they have a few different weeds in Florida).

First up is the first in a two-part review of weed control practices for landscape planting beds. We all know that fighting weeds is a significant part of work in both landscape and turf worlds. Chemicals vary for both of those applications, and we’ll get into that next time. For now, nonchemical weed control is where we’ll start. What comes to mind? If you’re thinking mulching and hand weeding, you’d be right. However, some best practices may impact other weed management choices and hopefully result in reduced herbicide application.

Types of nonchemical weed control:

Type Example Pros Cons
Mechanical disruption Mowing, hand-pulling, hoeing, tilling Depending on the application, it may be the most aesthetically pleasing approach. Time-consuming, labor-intensive, disrupts soil structure, may propagate weeds.
Physical barriers Geotextiles, landscape films, or fabrics In combination with mulch, it can be very effective Reapplication required, material may be destroyed by weeds growing on top of the fabric, does not contribute to soil health, in Kansas wind can be problematic
Cultural control Mulching, plant selection, fertilization and irrigation placement, thermal treatment Great for soil health (organic mulches), aesthetically pleasing, reasonable weed control when applied at least 3-inches deep Mulch type matters, reapplication, and scouting required, inorganic mulches do not contribute to soil health, and rubber mulch leaches zinc and other heavy metals into the soil.

 

Mulching is the A-#1 best choice for nonchemical weed control the average landscape bed. However, material selection is essential. For organic mulches, stick with large chunky (coarse) pine bark or pine needles and apply it at least 3-inches deep. Hardwood bark can be acceptable, but some species (and it’s not always easy to know which species is in the product you’re purchasing) have allelopathic chemicals which could damage ornamental plants. Fine-textured materials like compost and screened bark may encourage weed growth, so avoid those materials or refuse to accept a bark load that is too fine if you plan to use it for landscape mulch. These materials do break down over time which is good for soil health but requires reapplication.

Inorganic mulches are not ideal. They’re expensive, generally heavy, difficult to apply (and challenging to remove), and do not break down over time to contribute to soil health. Rock mulches, in particular, may bounce heat back up into the canopy of ornamental plantings, contributing to plant decline. Rubber mulches leach zinc and other heavy metals into the soil, which can also harm plants. I do not recommend inorganic mulches.

Now let’s address landscape fabric, geotextiles, etc. I don’t recommend plastic material because research has documented that water, air, and nutrients can’t get down to the soil, so ornamental plants don’t have access to the elements of life. While landscape fabric can be adequately effective, it is not usually so because weeds grow on top and through if not appropriately managed. Mulch cannot degrade into the soil (enhancing soil health and facilitating the mulch material staying in place). That’s an important point in Kansas, where the wind often whips loose mulch away from planting beds, particularly if landscape fabric is applied underneath. At that point, the landscape fabric is often unsightly, flapping in the wind with no mulch to hold it down (unless the “mulch” is rock). Landscape fabric is only effective for a short period of time and does not control perennial weeds. There may be some applications where landscape fabrics make sense, but I don’t recommend it in general.

Plant selection: we’re talking about perennial groundcovers now. If they grow densely enough and don’t die back to the ground during the winter, they may shade out some weeds. Of the studies mentioned in Dr. Marble’s review article, the ones that grow well in Kansas include:

  • Lady’s mantle (Alchemilla mollis): 1 to 1.5 feet tall, 1.5 to 2.5 feet wide, June bloomer, full sun to part shade (can handle almost full shade, particularly in the afternoon), tolerates rabbit and deer. May be an aggressive self-seeder, remove spent flowers to avoid spreading too much.
  • Catmint (Nepeta xfaassenii): 1 to 2 feet tall, 1.5 to 3 feet wide, blooms all summer, full sun to part shade, tolerates deer, dry soil, and shallow, rocky soil. Sterile.
  • Moss phlox (Phlox subulata): up to 0.5 feet tall, 1 to 2 feet wide, flowers March to May, full sun, attracts butterflies, tolerates deer, drought, erosion. Need good drainage.
  • Goldenrod (Solidago sphacelata): 1 to 1.5 feet tall and wide, flowers in the fall, attracts butterflies, tolerates deer, drought, erosion, clay soil, dry soil, and shallow-rocky soil. Can colonize through rhizomes and self-seeding (needs deadheading to manage).
  • Sheep’s burr (Acaena inermis ‘Purpurea’): 1 to 2 feet wide, 1.5 to 3 feet wide, blooms June to August, prefers full sun and dry soil (low maintenance), tolerates deer, drought, and shallow-rocky soil.

Of course, we have to think carefully about using plant choice as a nonchemical weed suppression tool because some plants can become invasive (Liriope spicata, for example). Be aware of the Kansas noxious and invasive weed lists; you can find them here: https://agriculture.ks.gov/divisions-programs/plant-protect-weed-control/noxious-weed-control-program. Side note: did you know we have Kudzu in Kansas? It’s true, sadly. Kudzu is an interesting plant, but that is a story for another day.

Hand weeding and cultivation are always an option, although labor-intensive (and thus costly). Without other control measures, weeds will likely pop up again quickly.

Here’s a fun one: Thermal weed control. That’s right, steam, hot water, flame from a propane burner, or solarization. Thermal weed control has limited applications because you need to be careful about the areas around where you use the tool. Ideally, the use of these tools will be centered on hardscapes and other non-planted areas to eliminate large perennial and grass weeds. Solarization is a long-term process where plastic is used to cover areas for an extended amount of time to kill weeds and weed seeds. It requires reapplication and could damage nearby ornamentals or other tools like hoses or irrigation heads. These are likely not your best choices for nonchemical weed control and additionally can be dangerous. Use these as a last resort, get training, read manuals, and BE CAREFUL!

Lastly, consider fertilizer and irrigation placement. In container-grown nursery crop settings, weed pressure can be reduced when fertilizer is dibbled or banded within the container substrate profile. Fertilizer placement makes a lot of sense because if Nitrogen is easy to access, weeds will go to town (and your ornamentals may starve). Interestingly, sub-irrigation in container studies can be adequate for weed control. However, studies of sub-irrigation in landscape beds have proven it to be an ineffective practice for managing weeds.

These choices depend a great deal on the project, application, and client tolerance for weeds. The best approach is likely to apply various weed control methods, which may include chemical controls for the longest-lasting effect. We’ll cover those next time.

Marble, S.C., A.K. Koeser, and G. Hasing. 2015. A review of weed control practices in landscape planting beds: Part I—Nonchemical weed control methods. HortScience 50(6):851-856. https://doi.org/10.21273/HORTSCI.50.6.851

Tips for Enhancing Efficacy of Preemergence Herbicides

Posted on by Jack Fry

By Dr. Jack Fry

Preemergence herbicide applications for crabgrass, goosegrass, foxtail, and other annual grasses are underway.  Here are some bullet points to consider to increase the efficacy of the herbicide you use.

Maintain turf density and mow higher.  Good turf density resulting from proper cultural practices for the grass you’re managing reduces encroachment of all weeds, including annual grasses.  Mowing at the higher end of the recommended range has consistently shown significantly lower populations of crabgrass and other annual grasses than mowing at lower mowing heights.

Apply before emergence.  Not all annual grass species emerge at the same time.  For example, goosegrass emerges later than crabgrass.  However, even within a species, emergence of new seedlings occurs throughout spring and summer.  With most preemergence herbicides, when seedlings have emerged, they will not effectively control those plants.  However, the application will control emergence of grasses beyond that date.  Dithiopyr (Dimension) does provide control of crabgrass that has emerged but has not begun to produce tillers.

Use effective strategies to guide application.  Calendar dates, soil temperature, flowering of ornamentals, and other strategies are all used to help guide applications and maximize herbicide residual during the period annual grasses emerge.  Here are a couple of articles related to this subject:

https://blogs.k-state.edu/turf/methods-of-predicting-crabgrass-emergence/

https://blogs.k-state.edu/turf/flowering-ornamentals-and-crabgrass-emergence/

Apply uniformly.  Uniform application is critical – just like distributing paint evenly over your house is aesthetically pleasing.  If you leave a section of the house unpainted, it’s clearly visible.  Good annual grass control requires uniform application; if an area is not treated, it’s likely you’ll seed weed emergence there. Uniform application is achieved by proper spreader or sprayer calibration, colorants that indicate areas that have been treated with liquid products, and applying the product in two directions (half rate in each).

Split applications.  Preemergence herbicides generally provide better suppression of annual grasses when applications are split (1/2 rate each application), usually 6 to 8 weeks apart.  This allows a higher level of herbicide presence on the soil surface, which will minimize weed emergence.  Here’s an article from Purdue on this subject:

https://turf.purdue.edu/wp-content/uploads/2012/06/15_AGRY_Patton_sequential20apps.pdf

Water in after application.  For preemergence herbicides to be activated and ensure uniform distribution on the soil surface, irrigation (or rainfall) after application is needed.

Find more information on weed control by clicking on the tags on the blog (left column), such as “weed control,” “crabgrass,” etc., or search by category on the right side of the page.

***Mention of trade names or commercial products in this article is solely for identification purposes and does not imply recommendation or endorsement, nor is criticism implied of similar products not mentioned by Kansas State University.***

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Testing for Winter Survival of Warm-Season Grasses

Posted on by Brooke Garcia

By Dr. Jack Fry

What a stretch of low temperatures we experienced in the state of Kansas from Februrary 6 to 19th! The lowest temperatures occurred on February 16th: Olathe, -18 F; Manhattan, -21 F; Wichita, -18 F. This makes those who are growing warm-season grasses concerned about how they’ll green up this spring. Snow cover is an important factor; more cover provides greater insulation from the extreme cold. Soil is a good insulator, too, which is one reason it’s a good idea to keep thatch to a minimum. When thatch accumulates, the growing points become elevated and are exposed to lower temperatures.

In our region, bermudagrass is the greatest concern, but freezing injury is also common on zoysiagrass. Areas that are most susceptible to freezing injury are those that experience shade during the growing season or are exposed to foot or cart traffic.

To look ahead and see if you might have winter injury, remove several plugs from each area that concerns you. Don’t just rely on a single plug – it doesn’t tell the story. Put them in pots and bring them in a greenhouse (if you have one) or on a windowsill within a warm room. Likewise, if you have grow lights you can put them under that will work, too. Warmer temperatures will encourage faster growth and evaluation. Give them 2 to 3 weeks under these conditions and look at how much green up you observe. Good green up makes us feel good about the approaching spring; lack of green up may require making plans for replanting.

Here are a couple of publications with related information:

 

Root decline, Pythium root rot, and anthracnose in recent samples

Posted on by kennelly

(Megan Kennelly, KSU Plant Pathology)

Here is a sample that came into the lab recently:

You can see turf decline, and if you look closely you can see some dark green algae in the brown area. Algae often indicates poor drainage. This site is in a low area with poor airflow. The site has a lot of underlying stress.

Here is a view of the washed-off roots sitting on the dissecting microscope. They should be a creamy white but instead they are more of a brown color. They were mushy in texture as well.

 

Finally below is a closer view in the compound microscope. You can see how the roots are dark. Healthy roots are much more clear/transparent. These are also lacking fine root hairs, and the outer tissues have sloughed off.

These symptoms occur frequently in sites with poor drainage. The roots sit wet, and oxygen flow is disrupted. The wet soil holds heat overnight as well.

The environmental stress alone can cause major root decline and turf damage.

In addition, these conditions can trigger Pythium root rot. (This particular sample did have some Pythium as well, I just had a hard time getting a clear photo). And, these stress conditions can also lead to crown anthracnose. I’ve seen a couple of samples with that disease lately as well. Anthracnose is more likely to chow down on turf that is already stressed.

Here is a link to a publication I’ve mentioned countless times on this blog:

http://www2.ca.uky.edu/agcomm/pubs/ppa/ppa1/ppa1.pdf

There are excellent sections on individual diseases, but there is also a detailed section about summer stress on page 6. Many of the stress-reducing practices listed there will also reduce susceptibility to diseases.

That publication does not discuss Pythium root rot (PRR). (It does discuss Pythium root dysfunction (PRD) which is related but different.) Here is a great resources on PRR:

https://www.turffiles.ncsu.edu/diseases-in-turf/pythium-root-rot-in-turf/

Each year, we say, “I hope this August isn’t a bad one”. This coming week there will be some lower highs (low to mid 80’s) and “lower lows” (mid-60’s overnight, and even some upper 50’s! Woohoo!). Cool temps will be a blessing. However, continued rain may exacerbate drainage problems.

Managing the diseases is important, but it’s critical to address the physiological/environmental stresses as well or the turf can still suffer major decline this time of year.

 

 

Euonymus Scale

Posted on by Brooke Garcia

By Brooke Garcia

This is the time during the summer season when Euonymus Scale may be extra noticeable on evergreen euonymus. The scale insect will appear as small, white dots covering the planting. If you are wearing darker clothing and come into contact with the shrub, you may notice the white “debris” coming off of the plant. The plant can quickly become infested and covered with this insect. Euonymus Scale is capable of killing the plant if left untreated. Keep a watchful eye on plantings during this time. There are cultural strategies that can be incorporated into the garden to reduce the likelihood of this insect becoming a problem, but it is extremely prevalent and may require chemical treatment.

Euonymus Scale Infestation On Euonymus Plants Located Near Building (Auth-Raymond Cloyd, KSU)

For more information about the biological characteristics of this insects, as well as cultural and chemical practices that can aid in prevention and/or treatment, visit the K-State Extension Entomology post here: https://blogs.k-state.edu/kansasbugs/2020/07/02/euonymus-scale-4/

Seeding Tall Fescue in January? Sure!

Posted on by Brooke Garcia

By Dr. Jack Fry

Identifying seeding windows for cool-season grasses,  like tall fescue, in our region is often difficult because weather is so different year to year.  For example, for autumn seeding, October 15 is often suggested as the deadline for seeding in northeast Kansas.  Seeding after that date doesn’t mean that there won’t be success – some years there may be, others year not.  The concern is that germination and emergence may still occur after mid-October.  However, the seedling that emerges may not mature to a point where it can survive the cold, dry conditions common during Midwest winters.

Following the mid October deadline, the next window for seeding opens around Thanksgiving and continues into March.  We call it “dormant” seeding.  Dormant seeding means that the grasses out in the lawn now are dormant and not growing.  In addition, the seed you scatter in mid-winter will also remain “dormant” until warmer conditions and moisture return in the spring.  Unfortunately, some of us remain dormant until spring as well – outdoor work in midwinter may not sound attractive.  Tall fescue germination is optimized between soil temperatures of 59 and 72 F, so seed applied in winter will remain inactive in the soil until it warms to near 60 F, and it will then begin to germinate.  Other grasses are also candidates for dormant seeding as well, including other species of cool-season grasses, buffalograss, and bermudagrass.

Seed-to-soil contact is critical.  If conditions are dry, vertical mowing or slit seeding may be possible.  In addition, a light topdressing of soil applied over seed can also maximize seed-to-soil contact.  Seeding on frozen soil is also possible, and seed-to-soil contact is improved as the soil thaws and freezes, which creates cracks in the surface in which seed can lie.  Covering or mixing seed with the soil, where it will likely remain for a number of weeks before germination, also prevents it from being a source of food for birds and rodents.

Twenty years ago, Ward Upham, Extension Associate in Horticulture and Natural Resources, did a study to evaluate dormant seeding month effects on tall fescue cover in May.  He seeded plots on the 15th of each month from December through March onto bare soil that had been tilled and raked.  On May 18, plots seeded in February and March each had an average of 80% coverage.  December and January seedings were each at about 60% coverage.  Ward suspected that having seed out in the environmental longer made in subject to erosion and consumption by animals.

Advantages to Dormant Seeding:

  • Sometimes it is drier in mid-winter than early spring, which allows outside work to be done. Seeding in April and May can be difficult months for seeding during frequent rainfall.
  • Spring emergence will occur at the earliest possible date.
  • There may be more time and labor available now that’s not available in the spring.

Disadvantages to Dormant Seeding:

  • Weather doesn’t always cooperate, and midwinter may be too wet to get it done. However, if just small areas are needing seed, that can be done by hand.
  • Stand establishment may not be as successful as seen with autumn seeding, the preferred time. And, just like spring seeding, weed competition will be greater as the stand matures.
  • Preemergence herbicides applied in late fall or in spring may inhibit germination and growth of the seedlings. Preemergence herbicides that can be used in the tall fescue seedbed include siduron (Tupersan) and mesotrione (Tenacity).

Research in progress: zoysia seedhead suppression

Posted on by kennelly

(Megan Kennelly, KSU Plant Pathology)

I was out looking at our zoysiagrass breeding plots the other day and in a couple of plots I saw some seedhead development:

 

This was unusual, as we typically see this in spring, and it’s probably just a unique physiology of these couple of breeding lines. Anyway, this observation prompted me to mention that we are continuing KSU’s work on zoysiagrass seedhead suppression. You may have seen the articles about the prior excellent work by Dr. Hoyle and colleagues which you can view here:

Suppressing Meyer zoysiagrass seedheads

and here (academic peer-reviewed version)

https://dl.sciencesocieties.org/publications/cftm/abstracts/4/1/180012?access=0&view=pdf

We are following up on this work with additional trials to hone in on the biology and management of seedheads, fine-tuning application timings of ethephon. Stay tuned for results in the coming 1-2 years as we collect data. The project team members are PhD student Manoj Chhetri, Jack Fry, Jared Hoyle, me, and Aaron Patton (Purdue). The project is funded by the GCSAA, Heart of America Golf Course Superintendents Association, and Kansas Turfgrass Foundation.

Fall Fertilization and Turf Tips

Posted on by Brooke Garcia

(By Jared Hoyle, KSU Turfgrass Research and Extension)

Dr. Bill Kreuser, Assistant Professor and Extension Turfgrass Specialist, at the University of Nebraska – Lincoln posted some great information on fall turfgrass fertility and some other fall turfgrass tips.

Dr. Kreuser quoted, “Fall is arguably the most import season for turfgrass managers. While we’re busy preparing for a new growing season in spring and trying to survive stressful conditions in the summer, fall is the time to recover from summer, renovate, and prepare for winter. It’s a season of seeding, cultivation, weed control, and fertilization. While fall is still widely considered the most important time to fertilize turfgrass, the fertilization recommendations have evolved over the past decade.”

I couldn’t agree with him more.  There has been lots of recommendations evolve over the years and just because “this” is way it has always been done doesn’t mean it is right.  See what Dr. Kreuser has to say and check out the links below.

 

  1. Rethinking Fall Fertilization
  2. Mid-Fall Turf Tips 

 

Tips and tricks on planting trees before you trick-or-treat

Posted on by kennelly

(Megan Kennelly, KSU Plant Pathology)

My family did a campfire and cooked our first pot of chili in awhile – it’s really feeling like fall! We have a few weeks remaining in October, and between now and Halloween is still a great time to plant trees and shrubs. Here are some articles with tricks of the trade before you trick-or-treat:

Nice summary from Johnson County:

https://www.johnson.k-state.edu/lawn-garden/agent-articles/trees-shrubs/planting-trees-shrubs-in-fall.html

Excellent nuts and bolts of tree planting:

https://www.bookstore.ksre.ksu.edu/pubs/MF3313.pdf

A few more details on methods:

https://www.bookstore.ksre.ksu.edu/pubs/mf402.pdf

Watering new trees and shrubs:

https://www.bookstore.ksre.ksu.edu/pubs/MF2800.pdf

Now, with all that, truly your most important FIRST step is deciding on what to plant. If you have not yet done your research on that question, here are some more resources on tree and shrub selection.

Trees and shrubs for difficult sites:

https://www.bookstore.ksre.ksu.edu/pubs/MF2205.PDF

Trees for Northeast Kansas:

https://www.kansasforests.org/community_forestry/community_docs/NE%20Kansas%20Preferred%20Trees.pdf

Trees for Northwest Kansas:

https://www.kansasforests.org/community_forestry/community_docs/NW%20Preferred%20Trees122016.pdf

Trees for Southwest Kansas:

https://www.kansasforests.org/community_forestry/community_docs/Pref%20Trees%20SW.pdf

Water-wise plants for south central Kansas:

https://www.sedgwick.k-state.edu/gardening-lawn-care/documents/Water%20Wise%20Plants%202015.pdf