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K-State Turf and Landscape Blog

Category: integrated pest management (IPM)

How to Enhance Efficacy of Preemergence Herbicides (and get Weed Control for Professionals publication!)

Posted on by Jack Fry

By Dr. Jack Fry

This blog post was presented last year, but we’re approaching that time of year again when crabgrass and other annual grassy weeds are approaching emergence.

As a reminder, if you want more detailed information on weed control in general, consider getting this publication that was developed by several state universities, including K-State, and was led by Purdue:  “Weed Control for Turfgrass Professionals” 

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

Autumn is the Right Time for Broadleaf Weed Control

Posted on by Jack Fry

Cool-season broadleaf weeds, including winter annuals and perennials, wait until temperatures cool down and then emerge during autumn.  The photo above was taken in Olathe in late October.  Targeting broadleaf weeds during autumn, when temperatures are suitable for application, results in good broadleaf weed control.  Immature weed seedlings are more susceptible to herbicides than mature weeds.  Find more information regarding weed control in this valuable resource. The updated “Turfgrass Weed Control Guide for Professionals – 2021” provides weed identification and control information that turfgrass professionals can use to develop effective weed control programs for golf courses, athletic fields, sod farms, lawns, and other turfgrass systems. The recommendations apply to the majority of the United States, with input from experts in Illinois, Indiana, Iowa, Kansas, Kentucky, Michigan, Minnesota, Missouri, Nebraska, New Jersey, New York, Ohio, Pennsylvania, and Wisconsin.

CLICK HERE to purchase the Turfgrass Weed Control Guide for Professionals – 2021

This guide will also be available for sale at the Kansas Turf and Landscape Conference on December 1 and 2, 2021 in Manhattan, KS.  You can download the conference brochure and get exhibitor information by CLICKING HERE! Complete online registration by CLICKING HERE!

 

New Publication: Industrial Weed Control

Posted on by Brooke Garcia

By Brooke Garcia

Visit the KSRE Bookstore to view the updated publication on Industrial Weed Control, which has a focus on right-of-way and industrial areas. This publication will describe how to manage weeds in the following areas:

  • near or around buildings
  • roads and roadsides
  • industrial sites and areas

“Excess vegetation can obstruct road visibility, create fire hazards, impair drainage, and reduce the useful life of structures. Reliability and public safety across rights-of-way and industrial areas require controlling unwanted vegetation.”  ~ Frannie Miller & Sarah Lancaster 

Get the PDF copy of the publication here: Industrial Weed Control 

How to Avoid Being “Bitten” by Mosquitoes

Posted on by Brooke Garcia

By Brooke Garcia

Have you ever wondered how to reduce the chances of being bitten by mosquitos?  The K-State Extension Entomology Newsletter has a great post within their June 24th, 2021 No. 12 issues about “How to Avoid Being “Bitten” by Mosquitoes.”

Photo by: Susan Ellis, Bugwood.org

The recent post features:

  1. Source Reduction
  2. Personal Protection
  3. Insecticides
  4. What does NOT work against mosquitos

Read more on the Entomology Newsletter here.

Celebrating Pollinators Year Around

Posted on by Brooke Garcia

By Brooke Garcia

It was Pollinator Week June 21-27, 2021! How did you take part during Pollinator Week? Perhaps you had an encounter with a buzzy friend in the garden or planted some native perennials that attract pollinators in the landscape.

Celebrating pollinators does not need to be confined to one week only. You can do this in so many unique ways in your personal garden or landscapes you manage or oversee.

Photo taken in David Traylor Zoo of Emporia, KS by Brooke Garcia.

Here are some creative ideas to help attract and celebrate pollinators in our favorite landscapes:

  • Plant native flower beds, gardens, or local grasses to your landscape area
  • Add pollinator plants to flower pots
  • Incoporate native bee houses into the landscape
  • Host a pollinator plant sale or pollinator festival/event
  • Host an educational event with K-State
  • Choose a mixture of plants that flower during spring, summer, and fall
  • Reduce or eliminate pesticides in certain areas of your landscape if possible
  • Incorporate plants that encourage beneficial insects
  • Reach out to others and educate! Informing clients and friends is a great way to encourage change.

Here are some more ideas featured in the Extension Entomology Newsletter.

These are just a few ways to help support pollinators all year around! Have any pollinator topics you’d like us to feature? Email us at gardenhour@ksu.edu.

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

 

 

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

Extension Publication Update

Posted on by Brooke Garcia

By Brooke Garcia

There is a new publications of interest recently updated through K-State Research and Extension by Dr. Raymond Cloyd:

“Magnolia scale, Neolecanium cornuparvum, is an insect pest of magnolia trees including star magnolia, Magnolia stellata, and saucer magnolia, Magnolia x soulangiana. Magnolia scale is native to the U.S. and is the largest soft scale in North America. This publication discusses the biology, damage, and management strategies that can be used to avoid plant damage caused by magnolia scale.”

Read more here: Magnolia Scale: Insect Pest of Magnolia Trees. MF3560. Raymond Cloyd.

Photo Credit: William Fountain, University of Kentucky, Bugwood.org

10 Rules for Planting Trees This Spring

Posted on by Brooke Garcia

By Brooke Garcia

This article was originally posted on March 18, 2021 on K-State Research and Extension News. For original article, please visit: Ten rules for planting trees this spring

Ten rules for planting trees this spring 

K-State horticulture expert shares tips to set you up for success

MANHATTAN, Kan. – If you’re planning to plant a tree in your yard this spring, there are some steps you can take to make sure your new landscape has its best chance of success.

Kansas State University horticulture expert Ward Upham shares the following ten rules for planting trees:

  1. Select the right tree for the site. To avoid serious problems, choose trees that are adapted to your location. Consider whether the tree produces nuisance fruit or if there are disease-resistant varieties available. For example, there are a number of crabapple varieties that are resistant to apple scab and rust diseases. Also consider the mature size of a tree to be sure you have enough room. Ask a local nurseryman for suggestions for trees adapted to your area.
  2. Keep the tree well watered and in a shady location until planting. When moving the tree, lift it by the root ball or pot and not by the trunk.
  3. Before planting, remove all wires, labels, cords or anything else tied to the plant. If left on, they may eventually girdle the branch to which they are attached. The root flare (point where trunk and roots meet) should be visible. If it isn’t, remove enough soil or media before planting so that it is.
  4. Dig a proper hole. Make the hole deep enough so that the tree sits slightly above nursery level. Plant the tree on solid ground, not fill dirt. In other words, don’t dig the hole too deep and then add soil back to the hole before placing the tree. The width of the planting hole is very important. It should be three times the width of the root ball. Loosening the soil outside the hole so it is five times the diameter of the root ball will allow the tree to spread its roots faster. 
  5. Remove all containers from the root ball. Cut away plastic and peat pots; roll burlap and wire baskets back into the hole, cutting as much of the excess away as possible. If you can remove the wire basket without disturbing the root ball, do it. If roots have been circling around in the container, cut them and fluff them out so they do not continue growing so that they circle inside the hole and become girdling roots later in the life of the tree. 
  6. Backfill the hole with the same soil that was removed. Amendments such as peat moss likely do more harm than good. Make sure the soil that goes back is loosened – no clods or clumps. Add water as you fill to ensure good root to soil contact and prevent air pockets. There is no need to fertilize at planting. 
  7. Don’t cut back the branches of a tree after planting except those that are rubbing or damaged. The leaf buds release a hormone that encourages root growth. If the tree is cut back, the reduced number of leaf buds results in less hormone released and therefore fewer roots being formed. 
  8. Water the tree thoroughly and then once a week for the first season if there is insufficient rainfall. 
  9. Mulch around the tree. Mulch should be 2 to 4 inches deep and cover an area 2 to 3 times the diameter of the root ball. Mulching reduces competition from other plants, conserves moisture and keeps soil temperature closer to what the plants’ roots prefer.  
  10. Stake only when necessary. Trees will establish more quickly and grow faster if they are not staked. However, larger trees or those in windy locations may need to be staked the first year. Movement is necessary for the trunk to become strong. Staking should be designed to limit movement of the root ball rather than immobilize the trunk. 

Upham and his colleagues in K-State’s Department of Horticulture and Natural Resources produce a weekly Horticulture Newsletter with tips for maintaining gardens and home landscapes. The newsletter is available to view online or can be delivered by email each week.

Interested persons can also send their garden- and yard-related questions to Upham at wupham@ksu.edu, or contact your local K-State Research and Extension office.