By Megan Kennelly, Professor, Turfgrass Disease Management & Development
Here in Kansas we see our most severe large patch symptoms in spring, but we can see it in fall, especially if conditions are cool and wet. Here, also, we’ve had pretty good success at suppressing spring symptoms with applications the prior fall.
We at KSU and others have been busy trying to tackle this disease in recent years, especially with the increasing interest in zoysia. For a review of research across the transition zone you can check out this article in Golfdom:
By Dani McFadden, Graduate Research Assistant, Horticulture and Natural Resources
It is that time of year when winter annuals and cool-season broadleaf weeds start emerging. Understanding how your herbicide is interacting in the soil and within the plant is important for effective weed control. Let’s take a shallow dive into the world of herbicide interactions so you’ll better understand the process a plant undergoes after an application.
Mode of action explains the entire sequence of events that happens from herbicide application to plant death, this includes the uptake, translocation and metabolism. This term is often confused with mechanism of action or site of action, which is the specific location at the cellular level where the disruption occurs. Contact herbicides (ex. diquat) injure the plant wherever they touch the plant, and often work quickly. We find that contact herbicides are more effective on small annual weeds compared to perennial weeds. Systemic herbicides (ex. glyphosate, 2,4-D) must be absorbed by the plant and then move throughout. In contrast to contact herbicides, systemic herbicides are very effective on perennial weeds. Since systemic herbicides are able to translocate to different parts of the plant, they are able to kill perennial weeds at the roots, tubers, and/or rhizomes.
So, how are commonly used herbicides effective against weeds? First, the herbicide needs to effectively contact the plant (more critical for contact herbicides compared to systemic herbicides) and then be absorbed by the plant. The compounds will then move to the site of action, and if there is enough toxicity within the site of action the plant will ultimately die.
Understanding the life cycle and biology of weeds will increase performance of the herbicide. However, there are several factors that can affect the uptake, translocation, and metabolism of the herbicide once it reaches the plant. Plant barriers such as waxy cuticles on the leaf surface or the casparian strip (a band-like wall that blocks the movement of water and solutes in vascular plants) can reduce herbicide uptake. Furthermore, climatic conditions and properties of the herbicide can influence efficacy. Here are some properties of herbicides that will help you understand how it will perform in certain environments at or following application:
Water solubility (Kow) is important because it affects behavior in the soil, formulation of an active ingredient, and separation of the herbicide into the plant. If herbicides have a high Kow they will be less soluble in water.
Soil adsorption (Koc) focuses on the retention of herbicide compounds and what influences persistence and availability of the herbicide. Many factors affect how herbicides are adsorbed, such as: moisture, clay content and organic matter, and soil pH. The Koc affects the herbicides tendency to bind to soil particles.
Volatility and particle drift is the physical drift that occurs during or immediately after application, with smaller droplets being more likely to drift than larger droplets. Furthermore, it is important to note that if the vapor pressure of the herbicide is high, then potential for non-target plant injury increases. Factors increasing volatility after herbicide application include: higher temperatures and increased soil water content. In addition, broadleaf herbicides containing high ester content are more volatile. To reduce volatilization applications can be incorporated into the soil or applied when weather conditions are favorable.
For plant absorption and translocation, herbicides must cross several barriers. It is important to read the herbicide label before use. If a surfactant is recommended, then one should be utilized. A surfactant can aid in decreasing surface tension and increasing absorption.
Topramezone app on goosegrass
Having knowledge on: 1) the biology and life cycle of the weed you are controlling; 2) properties of the herbicide you are applying; and 3) environmental conditions and soil factors at your site will aid in effective weed control.
It is imperative to always READ THE LABEL before applying herbicides for the correct rate, turfgrass tolerance, and important instructions for 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 73rd Annual Kansas Turf & Landscape Conference will be held on November 29 & 30 (Wednesday and Thursday) at the Hilton Garden Inn, Manhattan. The conference is an excellent way to learn about turf and landscape management, visit with old friends, network with new ones, and see all the latest products and supplies from local and national vendors.
The conference has been approved for commercial pesticide recertification hours:
1 Core hour
3A – 7 hours
3B – 7hours
GCSAA education points and International Society of Arboriculture CEUS will also be available by attending the conference.
Call Frannie Miller with the Pesticide & IPM Program at (620) 241-1523 or email fmiller@ksu.edu for additional information regarding the above trainings.
Commercial applicators may obtain recertification training credits any time during their active three year certification period. Commercial applicators have until December 31 of the year of expiration to earn credits. It is the commercial applicator’s responsibility to obtain the required credits.
The renewal period will open in October of the year of expiration. Make sure your renewal application and recertification fees are received by KDA by the December 31 expiration date of their certification to maintain continuous certification. For those who attended complete training during their certification period, the application form and fees will be accepted for 30 days following the certification expiration date. If certification fees are not paid to KDA by January 30, the applicator will be required to take the examinations to restart the certification process.
Credits may be viewed through the commercial applicator’s KDA Portal account.
The Kansas Turf & Landscape Conference will be held at the Hilton Garden Inn in Manhattan on November 29 & 30 (Wednesday & Thursday). The conference is an excellent way to learn about turf and landscape management. Visit with old friends, network with new ones, and see all the latest in products and supplies from local and national vendors.
Sessions include Basic Turf, Nursery & Landscape; Disease, Insects & Weeds; Sports Turf; Golf Course; Dealing with Pests.
By Maddy Rohr, K-State Research and Extension News Service
Prevent damage now by using insecticides, says K-State horticulture expert.
Managing plant pests is a common garden task, but Kansas State University horticulture expert Cynthia Domenghini says using preventive methods in the fall also is important.
“There are typically two generations of elm leaf beetles each year,” Domenghini said. “They overwinter as adults and emerge from their protective shelters in early spring. As elm trees develop leaves, the beetles move in and females begin laying eggs.”
Young Elm Leaf Beetle larvae are dark-colored, hairy grubs. Older larvae are yellow with two long, dark stripes. Adult beetles have green and yellow stripes.
“Larvae hatch and spread throughout the tree to feed. Larvae reach maturity within four weeks and seek shelter to pupate,” Domenghini said. Larvae may travel to the bottom of the tree or in cracks of bark.
Domenghini said larvae cause most of the damage by skeletonizing leaves of elm trees. Adult beetles chew holes through the leaves resulting in a change of color to brown and dropping.
Preventive methods include several insecticides. Healthy trees that have not been greatly affected should not be sprayed in the fall.
Larvae and adult sprays include acephate (Acephate, Orthene), spinosad (Natural Guard Spinosad, Conserve, Captain Jack’s Dead Bug Brew, Monterey Garden Insect Spray), lambda cyhalothrin (Scimitar, Spectracide Triazicide).
Domenghini and her colleagues in K-State’s Department of Horticulture and Natural Resources produce a weekly Horticulture Newsletter with tips for maintaining home landscapes and gardens. The newsletter is available to view online or can be delivered by email each week.
By Jack Fry, Professor and Commercial Turf Extension Specialist
The National Turfgrass Evaluation program is a cooperative effort between the non-profit National Turfgrass Evaluation Program, Inc., and the United States Department of Agriculture (USDA). NTEP is headquartered at the Beltsville Agricultural Research Center in Beltsville, Maryland. NTEP started in 1980 with J.J. Murray. For many years, Kevin Morris has been overseeing NTEP.
Zoysiagrass NTEP spring green up in 2023 at Olathe Horticulture Research and Extension Center.
NTEP trials are underway at three locations in Kansas. At Olathe, trials are being done on fine fescue (planted in 2020), tall fescue (planted in 2020), and zoysiagrass (planted in 2019). The fine fescue and tall fescue trials are low maintenance trials in Kansas, but not at all locations, which are mowed at 2.5 inches, receive no supplemental irrigation, and are fertilized with only 1 lb of nitrogen per 1,000 sq. ft. applied annually in autumn.
The zoysiagrass NTEP trial in Olathe is mowed at 0.75 inches 2 to 3 times weekly and receives 1 to 1.5 of nitrogen per 1,000 sq. ft. applied annually in early summer.
At the John C. Pair Center, the NTEP bermudagrass trial (planted in 2019) is being done and you’ll also find a specific article in the 2023 Turfgrass Research Report regarding their performance: https://newprairiepress.org/kaesrr/vol9/iss5.
Graduate student Dani McFadden evaluating creeping bentgrass NTEP trial at Milburn Country Club in Overland Park, KS.
In Overland Park, the NTEP creeping bentgrass putting green trial (planted in 2020) is being conducted at Milburn Country Club and maintained as they do other putting greens at the course. Steve Wilson, golf course superintendent at Milburn CC, has been very courteous to allow use of their nursery green area for this trial to be conducted and he oversees management of the site.
You can view data Kansas and multiple other locations from 2021, 2022 and many other years for trials conducted. The NTEP website allows access to data and results from all NTEP trials. Find information here: www.ntep.org
By Raymond Cloyd, Professor and Extension Specialist
Mimosa Webworm
Damage associated with mimosa webworm,Homadaula anisocentra, larvae/caterpillars is quite noticeable on honey locust,Gleditsiatriacanthos,and mimosa,Albizia julibrissin, trees throughout Kansas.
Mimosa webworm caterpillars feeding on leaves
The larvae/caterpillars are 1/2 of an inch long when full–grown and move backward rapidly when disturbed.
Caterpillars’ web leaves together on the ends of branches. Webbing typically starts at the tops of trees and protects caterpillars from natural enemies (parasitoids and predators) and insecticide spray applications.
Mimosa webworm webbing on end of branch
Heavily infested trees are brown or scorched in appearance because the caterpillars skeletonize the leaf tissue. Caterpillars eventually leave trees using a silken strand before pupating. Mimosa webworm pupates in bark crevices or pupae are attached to structures (e.g. buildings). There are two generations per year in Kansas.
Mimosa webworm caterpillar feeding damage
It is too late to apply an insecticide this time of year when trees are heavily infested with webbing because the caterpillars are protected from insecticide spray applications inside the leaf webbing. However, next year, you can manage mimosa webworm caterpillar populations by applying an insecticide when the caterpillars are initially present and exposed to insecticide spray applications.
You can use insecticides that contain the following active ingredients: Bacillus thuringiensis subsp. kurstaki, spinosad, bifenthrin, cyfluthrin, and permethrin. Read the label of each product to ensure that “webworms” are listed. Bacillus thuringiensis subsp. kurstaki and spinosad are stomach poisons so mimosa webworm caterpillars are killed after ingesting the spray solution on the leaf surface. High-volume spray applications are required so that the insecticide contacts the caterpillars or there are residues on the leaf surface.
Selective pruning, if possible, can quickly remove isolated or localized early infestations of mimosa webworm.
Fall Webworm
The fall webworm,Hyphantria cunea, second generation is now present throughout most of Kansas with nests present on trees, such as, hickory and walnut.
Fall webworm nest on walnut tree.
Fall webworm nests consists of silk webbing that encloses the ends of branches and leaves. Fall webworm larvae or caterpillars are pale-green, yellow to nearly white, with two black spots on each abdominal segment. Caterpillars are covered with long, white hairs.
Fall webworm nest on birch tree.
Fall webworm caterpillars feed on a wide-range of trees, including: birch, cherry, crabapple, elm, maples, hickory, pecan, mulberry, walnut, and willow. Fall webworm caterpillars, unlike caterpillars associated with the eastern tent caterpillar,Malacosoma americanum, remain within the enclosed nests and do not venture out to feed.
Close-up of fall webworm larvae.
Caterpillars consume leaves, resulting in branches with only webbing attached that contains fecal deposits (frass) or ‘caterpillar poop’. The nests will eventually dry-up as the caterpillars transition into pupae, with adults eventually eclosing (emerging) from the pupae later on in the growing season.
At this time of year, feeding by fall webworm caterpillars is not directly harmful to trees, especially larger trees. The most effective method of managing fall webworm infestations is to prune-out the nests that enclose the caterpillars, place into a plastic bag, and dispose of immediately. Insecticide spray applications are not be effective in managing fall webworm infestations because the caterpillars remain in the nests while feeding, which reduces exposure to spray residues. If insecticides need to be applied, for whatever reason, use high-volume spray applications that penetrate the protective nests, or use a rake to disrupt or open-up the nests so that insecticide sprays contact the caterpillars.
“The Census of Horticultural Specialties collects information to provide a comprehensive and detailed picture of the horticultural sector of the U.S. economy. It is the only source of detailed production and sales data for floriculture, nursery, and specialty crops for the entire United States. For the 2019 Census of Horticultural Specialties, an operation is defined as any place that grew and sold $10,000 or more of horticultural specialty products during the census year.”
If you have not filled this out, please do so ASAP—Be Counted!
Participating in listening sessions and discussions, filling out surveys, and contributing to grant review panels are critical ways you can help us so we can help you with teaching, research, and extension—the Land-grant university missions. Thank you for engaging with these essential processes.
By Cheryl Boyer, Professor and Extension Specialist, Nursery Crop Production and Marketing
At the Turf and Ornamental Field Day earlier this month, I mentioned a suite of KSRE resources for the turf and landscape industry focusing on safety. Many participants were interested in these publications—perhaps for in-house training this winter or on an as-needed basis for new and returning employees. In addition to the links below, there is a similar set of safety resources for the fruit and vegetable preserving and specialty foods manufacturing industry—let me know if you would like help finding them in the KSRE Bookstore.
While these items were published in 2008 and 2009, much of the content is relevant and consistent with current safety recommendations. Would you support updating these written resources or additional learning tools like videos or hands-on workshops? If so, please contact me (crboyer@ksu.edu) with your ideas or willingness to write a letter of support for a grant application. Thank you for caring about the safety of people working in our industry!
The 73rd Annual Kansas Turf & Landscape Conference will be held on November 29 & 30 (Wednesday and Thursday) at the Hilton Garden Inn, Manhattan. The conference is an excellent way to learn about turf and landscape management, visit with old friends, network with new ones, and see all the latest products and supplies from local and national vendors.
