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K-State Turf and Landscape Blog

Category: Weeds

Yellow Nutsedge Control

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)

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

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….

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

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

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

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.

Wild Violet Control

(By Jared Hoyle, KSU Turfgrass Research and Extension)

Wild violet or common blue violet is a persistent perennial broadleaf weed commonly found in thin, shaded turfgrass. The plant has heart-shaped, shiny leaves and can spread by rhizomes which makes it a difficult to control weed. The flowers are deep purple or bluish purple. There are many similar species but collectively, turfgrass managers just refer to them as wild violet.

Control has been difficult but can be achieve if you choose the right herbicide and rate. Triclopyr has proven to be effective in cool-season turfgrass and is contained in many different products that are on the market. But the key is to make sure that you apply more than 0.5 lbs ae/A of triclopyr to result in effective control. Not all products that contain triclopyr when applied at the recommended rate will have enough triclopyr for effective control.

At a quick glace through the Turfgrass Weed Control for Professionals manual (Get you copy here – https://www.bookstore.ksre.ksu.edu/Item.aspx?catId=545&pubId=20239) I found a table that shows the rates of triclopyr-delivered by various products at the low and high label rate. From that chart, the following are products that contain ≥ 0.5 lbs ae/A of triclopyr, when applied at the correct rate.

  • Aquasweep
  • Chaser 2 Amine
  • Chaser
  • Crossroad
  • Everett
  • Confront
  • 2-D
  • Tailspin
  • Turflon Ester Ultra
  • Triclopyr 4
  • Trycera

The take home message; To control wild violet in cool-season turfgrass use tricopyr (0.5 lbs ae/A), may different products contain triclopyr, not all products contain enough triclopyr, choose a product that when applied at the correct rate will result in at least 0.5 lbs ae/A of triclopyr.

If you are needing to control wild violet in bermduagrass or zoysiagrass; metsulfuron, sulfentrazon + metsulfuron and flazasulfuron are effective. Repeat applications are often required regardless of the herbicide.

Also, fall applications are best followed by spring applications.

Information from this post if from “Turfgrass Weed Control for Professionals” To get your copy today click here – https://www.bookstore.ksre.ksu.edu/Item.aspx?catId=545&pubId=20239

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.***

Don’t forget to follow me on twitter @KSUTurf.

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

White Clover and Yellow Woodsorrel Control

(By Jared Hoyle, KSU Turfgrass Research and Extension)

White clover is one of the most common weeds found in cool-season turfgrass.  It can grow in a wide range of environmental conditions and can tolerate many of our cultural practices.   It can also spread by seeds and by stolons. White clover is a perennial broadleaf weed that has trifoliate leaves that may or may not have a wedged-shaped mark. Although it is called white clover the flowers are white but may turn pink as they age.

Because white clover can fix its own nitrogen some see it as an important species to add beneficial soil nitrogen.  There had been some work done to explore using both clover and turfgrass in a mixture in their lawns.  Others may consider it as a weed.

If you consider it a weed, fall is a great time to try and control it.  But did you know 2,4-D, glyphosate and sulfentrazone do not control white clover?

For best control herbicides that contain clopyralid, dicamba, fluroxypyr, florasulam, metsulfruon, and/or quinclorac (also controls crabgrass) provide the best control when applied in the fall.

Yellow woodsorrel (Oxalis stricta) is a perennial or annual broadleaf weed that has clover-like trifoliate heart shaped leaves.  Yellow woodsorrel most commonly spreads by seeds that are contained in a capsule that when it explodes ejects the seeds.  It can be confused with clover but has yellow flowers with five petals.  You can find this weed in a wide range of soil conditions and can commonly be confused with black medic, birdsfoot trefoil and white clover. A similar species is creeping woodsorrel but it is most commonly found in landscape plantings while yellow woodsorrel is most commonly found in turf.

To control oxalis, herbicides that contain triclopyr and fluroxypyr are very effective.

Herbicides that contain fluroxypyr include;

  • Battleship III
  • Escalade 2
  • Momentum FX2
  • Tailspin
  • Vista XRT

Herbicides that contain triclopyr include;

  • 2-D
  • 4-Speed XT
  • Battleship III
  • Chaser
  • Chaser 2 amine
  • Confront
  • Cool Power
  • Eliminate
  • Horsepower
  • Momentum  FX2
  • Tailspin
  • Three-Way Ester II
  • Turflon Ester Ultra
  • Turflon II amine
  • Triclopyr 4
  • TZONE

Always remember a healthy turfgrass stand through proper maintenance is the best weed control and can help minimize clover and yellow woodsorrel in you turfgrass.

Information from this post if from “Turfgrass Weed Control for Professionals” To get your copy today click here – https://www.bookstore.ksre.ksu.edu/Item.aspx?catId=545&pubId=20239

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.***

Don’t forget to follow me on twitter @KSUTurf.

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

K-State turfgrass specialist urges mid-summer checkup on lawns

Many Kansas landscapes include warm-season grasses, which require a little care in order to stay healthy during the hot summer months.

Hoyle says warm-season grasses may need fertilizer to remain healthy

MANHATTAN, Kan. – Kansas State University Associate Professor and Extension Turfgrass Specialist, Dr. Jared Hoyle says homeowners ought to be thinking about a mid-summer checkup on their lawns, which likely includes applying fertilizer and weed killer.

Many Kansas summer landscapes include warm-season grasses, namely bermudagrass, zoysiagrass and buffalograss. Each of those requires a little care in order to stay healthy through the hot weeks ahead.

“Those three grasses are not all created equal and some grow faster than others, which means we need to feed them a little bit different,” said Hoyle, an associate professor in the Department of Horticulture and Natural Resources.

For bermudagrass and zoysiagrass, Hoyle suggests applying a total of 1-3 pounds of nitrogen per 1000 square feet during a typical growing season, which is the beginning of May through the middle of August.

“You can split that up into multiple applications of a quick release fertilizer, or you could do fewer applications of a slower release,” he said. “But the main goal is 1-3 pounds of nitrogen per 1000 square feet regardless of what number or percentage product you’re using.”

Buffalograss does not require as much nitrogen. Studies at Kansas State University indicate that “about 1 pound of nitrogen per year for 1000 square feet is good,” according to Hoyle.

“It’s hard to split up a pound over multiple applications, so that’s one where you might want to look at a slow release to put that pound of nitrogen per 1000 square feet throughout the year,” he said. “You can do that right now and that will get you through the rest of the year with a slow release fertilizer.”

In addition to fertilizing warm-season grasses, Hoyle said homeowners should be looking at ways to control thatch and weeds in the lawn.

“We really like to preach that if you are going to do something with the lawn — whether it is fertilizing or watering — do it when it’s actively growing,” Hoyle said. “Right now, with warm-season grasses, if you have a thatch problem, you can tear that area up (with a verti-cutter or slicer), fertilize the lawn, and it will grow right back in. If you try to do that during the fall or spring months, there will be periods of time when the lawn isn’t growing, or delayed growth, and it could lead to more problems.”

Among weeds, crabgrass and yellow nutsedge are two of the most troublesome this time of year.

““I’m seeing a lot of crabgrass and yellow nutsedge and I blame it on the weather,” Hoyle said. “Yellow nutsedge loves flooded, compacted soils and because of periodic flooding around the state, I have seen a lot of areas that typically never have yellow nutsedge. It’s a weed to keep an eye out with the weather conditions as they have been.”

To control yellow nutsedge, look for products with the active ingredients halosulfuron or sulfrentrazone, he said.

Crabgrass that has already emerged can be treated with products that include the active ingredient quinclorac.

Hoyle noted that homeowners should be patient when applying herbicides to yellow nutsedge and crabgrass; it might take more than one application to control those weeds.

K-State’s Department of Horticulture and Natural Resources publishes a weekly horticulture newsletter with updated information on lawn care and other turfgrass issues. Residents may also contact their local extension agent.