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K-State Turf and Landscape Blog

Category: Weeds

Seeding after Herbicide Application

Posted on by Jack Fry

By Daniele McFadden (recent M.S. graduate at K-State)

With spring in full swing many of you are taking advantage of the warm soil temperatures and overseeding turf areas. Often times we can mistakenly coincide our spring-time herbicide applications with seeding cool-season turf. So, are your new seedlings going to mature and develop if this happens? Research was done over the last two years to evaluate how several herbicides affect the emergence and growth of tall fescue and Kentucky bluegrass when seeded after application.  Following are some takeaways from these experiments.

The good:

  • When dandelions and other common broadleaves start to appear, a standard three-way postemergence broadleaf product containing 2,4-D + MCPP + dicamba (numerous trade names) is often applied. In both the field and greenhouse, we found that seeding tall fescue into an area treated with this herbicide combination was safe on the seedlings, and was comparable to tall fescue growth in areas where the herbicide wasn’t applied.
  • Other combination products used for control of broadleaf weeds were found safe on tall fescue seedlings when seeding was done 0 to 14 days after herbicide application. These herbicides included:
    • Carfentrazone-ethyl + MCPP + 2,4-D + dicamba (SpeedZone)
    • Fluroxypyr + halauxifen-methyl + 2,4-D (GameOn)
    • Triclopyr + pyraflufen-ethyl + 2,4-D + dicamba (4-Speed XT)

The bad:

  • Playing catch-up with yellow nutsedge control? Applying halosulfuron-methyl (Sedgehammer and other trade names) in late summer or early fall for the control of nutsedge could affect your tall fescue and Kentucky bluegrass seedlings if seeding occurs within two weeks of application. Both cool-season grasses emerged in the field with mild chlorotic symptoms that went away within 8 weeks after seeding. However, a closer look at root development showed that seeding tall fescue into soil treated with halosulfuron-methyl significantly stunted development. The Sedgehammer label guidelines clearly state that a four-week delay after application is needed.  Plan your nutsedge control earlier in the summer so it does not interfere with early fall seeding.

The ugly:

  • Did you accidentally apply a preemergence herbicide for crabgrass control before seeding? You might be wasting your seed. Our studies found that seeding tall fescue or Kentucky bluegrass into an area treated with dithiopyr (Dimension) greatly inhibited growth of the seedlings.

Bottom line – reading the label to learn how soon seeding can be done after herbicide application is critical. Labels on some of these products indicate that seeding should be done after a longer interval has passed after application compared to what was observed as required in this research.  Seeding guidelines on labels must be followed; that said, research results from this project provide useful information to herbicide manufacturers and turf managers who may unknowingly seed into herbicide-treated areas.

Evaluating emergence of tall fescue and Kentucky bluegrass when seeded 0 to 14 days after herbicide application in Manhattan, KS.

These research results will soon appear in greater detail in K-State’s 2021 Turfgrass Research Research Report.

***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.***

 

Don’t Moss with Me

Posted on by Jack Fry

Silvery thread moss has been an increasing problem on golf course putting greens over the past couple of decades.  Moss is a bryophyte, and that makes it different from most plants.  It doesn’t have roots, but rather rhizoids that serve as an anchor, but aren’t as efficient at absorbing water and nutrients compared to roots.  It also grows across a wide range of temperatures.  It can be actively growing when creeping bentgrass or annual bluegrass appears dormant in late fall or early spring.  It can also experience severe drought for months (or years), and regrow once water returns; no other weeds we deal with in turf are that resilient.  Research was done on silvery thread moss over several years at K-State by graduate students Dr. Cole Thompson (now Director of Research for the USGA) and Dr. Zane Raudenbush (Dr. Raudenbush just left The Ohio State University to join Davey Tree Company).  Here are some things to know regarding how management of putting greens will influence moss that came from their research:

Things that make it happier:

  • Mowing lower promotes more moss encroachment. For example, research showed that mowing at 0.125 in vs. 0.157 in resulted in greater moss populations.
  • Areas that are thin are susceptible to moss encroachment, so maintain turf density.
  • Moss loves water. If you’re watering frequently, you’ll favor its growth.
  • Soluble nitrogen applied as a liquid on a frequent interval (spoon feeding) encourages the growth of moss.

Things that help suppress it:

  • Mow higher and maintain turf density.
  • Water less frequently while still meeting the needs of the turf.
  • Fertilize with granular products that allow slower N release.
  • Core aerify, verticut, and topdress. Although some may think they could spread moss with cultivation, research has shown that moss populations can be reduced by these practices, which is due in part because the moss colonies are disturbed and allow creeping bentgrass to occupy those areas.
  • Apply products for moss suppression. The most popular product used for this is Quicksilver, which contains the active ingredient carfentrazone-ethyl and is labeled for use on greens.  Follow the label on Quicksilver for effective moss suppression (don’t expect complete control); using this or other products labeled for moss in combination with aforementioned cultural practices will be the best approach.

Here are some useful resources on moss:

An article on the K-State webpage that give more information on moss biology and control:  https://www.plantpath.k-state.edu/extension/documents/turf/moss_2015.pdf

A video by Dr. Zane Raudebush, former K-State graduate student who conducted research on moss here and as a faculty member at The Ohio State University:  https://www.turfnet.com/turfnet-tv.html/winfieldtv/raudenbush_silvery_thread_moss/

A summary of the research Dr. Raudenbush did at K-State in Golf Course Management magazine:  https://www.turfnet.com/turfnettv.html/winfieldtv/raudenbush_silvery_thread_moss/

Some specifics regarding N fertilization and moss:

https://www.golfdom.com/nitrogen-fertilization-and-silvery-thread-moss/

***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.***

Don’t forget to follow the K-State Turf and Landscape Team on Twitter @KSUTurf

Also, visit our facebook page www.facebook.com/KSUTurf

 

 

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.***

Don’t forget to follow the K-State Turf and Landscape Team on Twitter @KSUTurf

Also, visit our facebook page www.facebook.com/KSUTurf

Yellow Nutsedge Control

Posted on by Brooke Garcia

Revised by Brooke M. Garcia, original post by Dr. Jared Hoyle

We have been receiving some precipitation recently across the state of Kansas. Even if you have received little rain in your area, you may be seeing yellow nutsedge popping up everywhere. Yellow nutsedge does favor moist soils but it can also grow in well-drained sites.

 

One of the easiest ways to identify yellow nutsedge is by a couple special features;

  • erect
  • persistant
  • yellow inflorescence
  • gradually tapering leaves to a sharp point
  • tubers not in chains
  • triangular stem

To control yellow nutsedge, if you can get applications out before tuber production then you will see increased control. But beware, yellow nutsedge will continue to grow as long as the environment is favorable for growth, so more than one application may be necessary.If using a herbicide application timing is critical. During mid-summer, yellow nutsedge starts making tubers and if you apply herbicides before tuber production you will get better control. If you wait until the yellow nutsedge is big and starting to make tubers then you will be playing catch-up all year. So sooner is better.  Don’t wait for it to get too big.

Here are some options for yellow nutsedge control for turfgrass professionals;

  • pyrimisulfan (new herbicide that provides yellow nutsedge control)
  • sulfentrazone
  • halosulfuron
  • iodosulfuron
  • mesotrione
  • bentazon
  • triflozysulfuron
  • flazasulfuron
  • sulfosulfuron

There are many different products out there that contain these active ingredients so just make sure you have an active ingredient that has yellow nutsedge control! Also make sure you check for turfgrass tolerances.

Always remember to READ THE LABEL for the correct rate, turfgrass tolerance, and specific instructions before application.

***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.***

Be sure to follow our KSU Turf Facebook page: www.facebook.com/KSUTurf

Consider Postemergence Crabgrass Control When Plants are Young (Now)

Posted on by Brooke Garcia

By Dr. Jack Fry

Crabgrass is now becoming quite visible. If you didn’t apply a preemergence herbicide, or had some crabgrass emerge even where it was applied, now is the time to consider postemergence control. If a preemergence herbicide was applied, but you’re still seeing crabgrass, there may have been variability in uniformity of delivery over the area to which it was applied. If new sod was laid recently, it’s common for crabgrass to emerge through the seams. Control is easier when plants are young, for they are rapidly growing and have a thinner leaf cuticle. Make sure the crabgrass plant isn’t under stress before you apply the herbicide; rainfall or irrigation on the area within a few days prior to application can help ensure the herbicide is absorbed and translocated. Dr. Hoyle wrote a nice summary of best approaches to postemergence crabgrass control here:  https://blogs.k-state.edu/turf/postemergent-crabgrass-control

In addition, consider purchasing Turf Weed Control for Professionals, which was developed by cooperatively by numerous universities in the Midwest, including K-State. It can be purchased as a hard copy or a PDF download here:  https://mdc.itap.purdue.edu/item.asp?Item_Number=TURF-100

Young crabgrass emerging in a stand of zoysiagrass in Olathe this week.  Postemergence herbicides are most effective when crabgrass plants are young, and not under drought stress.

Crabgrass Has Emerged

Posted on by Brooke Garcia

By Dr. Jack Fry

Crabgrass emergence was evident last weekend – at least in Olathe, KS (picture below).

Crabgrass seedlings (inside white border) emerging on April 19, 2020 in Olathe, KS.

 

This was on bare soil next to a paved sidewalk. It can take a few weeks longer for crabgrass to emerge within areas of thin turf due to cooler soil temperatures (see article on timing herbicide applications here: Flowering Ornamentals and Crabgrass Emergence). So, on a lawn of acceptable quality (and no bare areas), you should still have time to get a preemergence herbicide out. Once you see crabgrass such as this emerging within a lawn, consider using a preemergence herbicide that has postemergence activity, such as dithiopyr (Dimension) or mesotrione (Tenacity). Of course, there are also a number of postemergence herbicides that can be used for crabgrass control as well.

Always remember to READ THE LABEL for the correct rate, turfgrass tolerance, and specific instructions before application!!!

***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.***

The Star-of-Bethlehem makes an appearance….

Posted on by Brooke Garcia

By Brooke Garcia (Modified original post written by Dr. Jared Hoyle)

Photo taken by Brooke Garcia

Recognize this weed? This time of year, we are beginning to see a lot of star-of-bethlehem popping up in lawns throughout Manhattan, KS. In my neighborhood, which is one of the oldest areas in Manhattan, it seems to be in every lawn. We struggle with this particular weed every year in our turf, as well as our landscape beds.

Photo taken by Brooke Garcia

It is a very pretty plant with showy, 6-petaled white flowers that have a distinct green stripe underneath. It is a perennial bulb that sometime appears to look like clumps of grass. It can be hard to spot in a freshly-fertilized, green lawn. The green hues blend together. The leaves are linear and smooth, flat in cross-section and have a with midrib.

This plant likes shady and moist areas of the lawn, but I have also seen it grow in the sunniest locations of my lawn too. With the recent moisture and more on the way we are not short of moist areas in the lawn around Manhattan right now.

Although it is has very distinctive characteristics it can be confused with other plants that are commonly found in lawns; crowpoison (Nothoscordum bivalve),spring beauty (Claytonia virginica), wild garlic (Allium vineale) and wild onion (Allium canadense).

If you do not have a lot of this weed in your turf or landscape beds, it can be effective to hand-dig the plant and bulb completely out of the affected area. However, the leaves tear quite easily. Thus, it can be difficult to completely eradicate the entire plant using the hand-removal method.

For chemical control there are couple of options.  Both sulfentrazone and carfentrazone have shown to be very effective.

For additional information about Star of Bethlehem, see the recent post written by Ward Upham:

Wild Onion, Wild Garlic, and Star-of-Bethleham

***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.***

Student Spotlight: Dani McFadden

Posted on by Brooke Garcia

By Brooke Garcia

Meet Dani McFadden! 

Dani McFadden is currently enrolled at Kansas State University pursuing her M.S. in Turfgrass Science, with an emphasis in Weed Science. She anticipates graduating in May 2021.

McFadden also holds an undergraduate degree from K-State in Horticulture, with a focus in Golf Course and Sports Turf Management.

When outside of class, McFadden loves walking around golf courses, sports fields, and home lawns to apply what she is learning in school. She enjoys being able to identify weeds and common diseases, as well as applying her knowledge of herbicides and fungicides.

McFadden’s favorite hobbies include playing golf with friends, fishing, and attending sporting events. More specifically, she likes attending sporting events that are played on natural grass.

Research Focus: Testing Labeled Restrictions on Seeding Timings after Herbicide Application

Here is what McFadden has to say about her research…

“Many people want to know when they can seed their lawn after herbicide application. Most labels restrict seeding until 2-4 weeks after application. My research includes seeding a stand 0, 3, 7, and 14 days after herbicide application along with the effects of different irrigation amounts on seedling germination. I am also doing research on tall fescue conversion to buffalograss after glyphosate applications.”

What’s next for Dani McFadden?

McFadden will always love mowing greens in the early morning while watching the sunrise. This is something she hopes everyone will have the chance to do. Looking ahead, she hopes to start a career with a chemical company as a territory manager. Through networking, she can continue to connect with great superintendents and turf managers in this industry. The “people in this industry is what makes being a turfgrass student so great,” says McFadden. 

Student Spotlight: Nic Mitchell

Posted on by Brooke Garcia

By Brooke Garcia

Meet Nic Mitchell! 

Mitchell is currently enrolled at Kansas State University pursing his Master’s degree in Horticulture, with an emphasis in Turfgrass Science and Weed Science. His undergraduate degree is from University of Nebraska-Lincoln in Turfgrass and Landscape Management.

So we asked him….why Turfgrass? 

Mitchell highlighted his love for turfgrass began around the time when his parents let him mow the lawn. He grew up on a nine-hole golf course in Aurora, Nebraska, and he became interested in the various mowers and different heights of cut.

Mitchell also shared his passion for playing golf. He had the opportunity to work several summers at his hometown golf course, where his interest in turfgrass continued to grow. Throughout his college studies, he eventually changed majors to pursue Turfgrass Management. This opened the doors to a variety of unique learning opportunities, including an internship in Jackson, Wyoming and a marketing internship with WinField United. These experiences helped Mitchell realize that he wanted to work in the turfgrass industry.

Dr. Jared Hoyle presented Mitchell with the opportunity to attend Kansas State University to work towards his M.S. Mitchell says that he has had a wonderful experience, and he is forever grateful for the opportunity to be apart of the K-State family.

Let’t talk research. 

Mitchell’s research is focused around Herbicide Programs for Seasonal Windmillgrass Control. Here is what Mitchell has to say about his research:

“Windmillgrass (Chloris verticillata Nutt.) is a problematic perennial grassy weed commonly found in the mid-west. Currently, there are the only two labeled chemical control options in turfgrass. Tenacity (mesotrione) is labeled for two applications for control while Pylex (topramezone) is labeled for a single application for control. We conducted research to determine if a single application of a common selective perennial grass herbicides would completely control windmillgrass, and to their efficacy when applied at spring, summer, and fall application timings. The next research study that we conducted was to explore the addition of triclopyr to mesotrione, topramezone, and fenoxaprop as well as triclopyr alone. Sequential applications of these herbicides and herbicide combinations were also applied. The last research trial we conducted was to determine the effects of windmillgrass response to glyphosate at different rates with fall applications similar to common recommended perennial weed control options.”

What’s next for Nic Mitchell?

Mitchell will be finishing up his M.S. program this December. His thesis presentation is on December 2nd, 2019 at 12:00pm in Throckmorton Plant Sciences Center. Following his thesis, he will be working for Corteva Agriscience as an Associate Territory Manager with their Turf and Ornamental business. Wish him the best of luck on his future endeavors!

See below for more information on his thesis presentation:

The (ob)noxious weed: Field Bindweed

Posted on by Brooke Garcia

By: Brooke Garcia

Perhaps you don’t recognize the name, but you may recognize the white flowers of this perennial weed called Field Bindweed. If you can’t recall the flower, you have probably still had an interaction with this weed in your garden or landscape. Don’t be fooled by the flower, as this is an (ob)noxious weed in the field and landscape.

Better Kansas Blog features a post that highlights this weed, as well as valuable links to additional information. For more information, click here.

Here is the link from Extension Agronomy: Fall Control of Bindweed

Here is a link from KSRE Johnson Country: Bindweed: a noxious weed

***Photo provided by Better Kansas Blog.