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K-State Turf and Landscape Blog

Category: Insects

How to Protect Trees from Elm Leaf Beetles

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.

Article originated from K-State Research and Extension News

Mimosa and Fall Webworm Damage in Trees Throughout Kansas

By Raymond Cloyd, Professor and Extension Specialist

 

Mimosa Webworm

Damage associated with mimosa webworm, Homadaula anisocentra, larvae/caterpillars is quite noticeable on honey locust, Gleditsia triacanthos, and mimosa, Albizia julibrissin, trees throughout Kansas.

Mimosa webworm caterpillars feeding on leaves

The larvae/caterpillars are 1/2 of an inch long when fullgrown 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.

Articles originated from the Kansas State University Extension Entomology Newsletter

Entomology Department Insect Diagnostics

By Anthony Zukoff, Extension Associate, Entomology

The Entomology Department’s Insect Diagnostics service continues to accept digital identification requests.  Our extension specialists’ areas of expertise include home and structural pests, horticultural and garden pests, pests of medical and veterinary importance, agricultural pests as well as general “what’s this bug?” requests.  Members of the public seeking assistance identifying an insect or insect related problems can access the Insect Diagnostics ID Request Form online.

After providing observation information such as location and date of the sighting, followed by answering a set of questions intended to help with the identification process, one can then upload up to 3 photos and submit the form.  The inquiry is then forwarded on to one of the entomology extension specialists.  Within a few days, usually less than two, the identity of the insect along with appropriate life history information and/or control measures is then sent to the client by email or phone.

The online submission process takes only a few minutes and can be accessed with desktop computers and mobile devices. If you need insect identification assistance, submit a request at https://entomology.k-state.edu/extension/diagnostician/.  Any questions about the program can be submitted to Insect Diagnostics Program Coordinator, Anthony Zukoff at azukoff@ksu.edu.

Got Plant Questions? The K-State Plant Disease Diagnostic Lab Has Answers.

By Chandler Day, Associate Diagnostician, K-State Plant Disease Diagnostic Lab

 

 

A quality diagnoses starts with a quality sample. A sample can be physical plants or digital images of plants. Digital images are a great screening tool to determine if a physical sample is required for diagnoses. In order to make a diagnosis, the quality of the images and/or samples is extremely important. Follow these tips for submitting your plant health questions. If you ever have questions about a plant problem, how to collect and/or ship a sample, feel
free to call or email us.

Inform. Collect. Ship.

Inform:

Send photos and background information to clinic@ksu.edu!

Three types of high quality digital images are an excellent way to pre-screen plant health issues.

  1. Symptoms up close (Fig. 1)
  • Take zoomed in photos of the problem/symptoms.
  • Ensure the image is in focus by tapping the image before you take the shot.
  • Examples of symptoms: leaf spot, branch die-back, sunken tissue, scorched leaves.
Fig 1. Close-up and focused image of leaf spots on iris.

 

  1. Entire plant. (Fig. 2.)
  • Take photos of the entire plant that includes all plant parts from soil level to the top of the plant.
  • Ensure the symptoms are still visible in this type of image.
  • Example: whole tree or shrub (trunk/base to top of crown).

 

Fig. 2. Photo of entire Iris plant with leaf spot still visible.

 

  1. Landscape pattern. (Fig. 3.)
  • Stand back and capture the entire landscape where the plant resides.
  • Include in the photo the surrounding plants, concrete, rocks, drain spouts, or whatever else is near the symptomatic plant. Don’t worry if the symptoms cannot be seen in this type of image.
  • The importance of this image is not to capture the symptoms on the plant but to capture the landscape. This gives us look at how the affected plant is growing within the site and if there are any site issues that might be contributing to the problem.
Fig. 3. Overall landscape view of flowerbed with Iris plants.

 

Useful background information:

  1. Site history:
    • Soil types, drainage, slope, sunny or shady problem areas, previous construction activity, proximity to structures such as roads or sidewalks, etc.
  2. Irrigation practices:
    • Frequency of irrigation, length of time, irrigation application method (sprinkler, drip, hand held hose), time of day
  3. Chemical history:
    • Pesticide usage and timing, fertilizer applications, etc.
  4. Pattern on plant:
    • Describe the problem. Are symptoms on new or old growth? Top or bottom of plant?
  5. Pattern in landscape:
    • One host or multiple hosts? Other plants in the landscape showing similar symptoms?
  6. Timing:
    • When did the symptoms occur: All at once? (i.e. after a storm?) Slowly over time?

 

Collect:

  • Complete the sample submission form with as much information as possible.
  • Send a “healthy” plant and a “sick” plant.
  • Submit entire plants when possible including roots. (EX. Tomatoes, annuals, turf grass, etc.)
  • DIG up plants. Do NOT pull up plants as this can damage the roots.
  • Bag roots separately and then place entire plant into larger plastic bag.
  • Do NOT add water or use paper bags. These degrade the sample quality and affects the diagnostic process.
  • For specific collection guidelines, go to the K-State Plant Disease Diagnostic Lab webpage, scroll down to where it says collection tips, and use the arrows on the right hand side to navigate to the appropriate collection strategy.

 

Ship:

  • Collect and ship samples on the same day. If this is not possible, store plants in plastic bags in the refrigerator until shipping is possible.
  • Ship plants overnight using UPS or FedEx. UPS can take up to 14 days even with 2 day priority shipping.
  • Ship on or before Wednesday to avoid weekend storage.

 

The K-State Plant Disease Diagnostic Lab is here to help you identify your plant health problems. If you ever have questions about a plant problem, how to collect and/or ship a sample, feel free to call or email us.

 

K-State Plant Disease Diagnostic Lab
4032 Throckmorton PSC
1712 Claflin Road
Manhattan, KS 66506
clinic@ksu.edu
785-532-6176

 

Japanese Beetle Activity

By Raymond Cloyd, Horticultural Entomology/Integrated Pest Management

Japanese beetle adults feeding on leaf

Japanese beetle, Popilla japonica, adults are present throughout Kansas feeding on many plants in landscapes and gardens, including: roses (Rosa spp), littleleaf linden (Tilia cordata), oak (Quercus spp.), Virginia creeper (Parthenocissus quinquefolia), crabapple (Malus spp.), grape (Vitis vinifera), and common garden canna (Canna x generalis).

The strategies to manage Japanese beetle adult populations are limited and have been for many years. The primary strategy involves spraying contact insecticides to kill the adults in order to reduce plant damage.

Japanese beetle adults are 3/8 to 1/2 of an inch long, metallic green with coppery-brown wing covers. There are approximately 14 white tufts of hair along the edge of the abdomen. Japanese beetle adults live up to 45 days feeding on plants over a four-to-six-week period. Adults feed on many horticultural plants including: trees, shrubs, vines, herbaceous annual and perennials, vegetables, fruits and grapes.

For more information including how to manage Japanese beetle adult populations, read the latest Kansas Insect Newsletter: https://entomology.k-state.edu/doc/extension-newsletters/2023/KSInsectNewsletter%2010.pdf

 

Unmanned Aerial Vehicle Pesticide Applications – What You Need to Know!

By Frannie Miller, Pesticide Safety and IPM Coordinator

There is a good deal of interest in using drones, also called unmanned aerial vehicles (UAVs) for the application of pesticides. In our context, a drone is a small, remotely controlled fixed-wing or rotary-wing aircraft. A drone application might be appealing to individuals wanting to spray where it is not practical or desirable to use a traditional spray, or perhaps, for spot spraying.  However, applications are limited by the size of the payload the drone is able to carry and compliance and logistics for such applications can be challenging. Downdraft can affect the deposition of the product and cause off-target movement or volatilization. If you are an applicator who is considering using a drone for applications, here is some basic information regarding licenses that you need to know before you apply any pesticides.

Drone image, courtesy of Brett Bultemeier, University of Florida, Pesticide Information Office

First, any individual who will be operating a drone for pesticide applications shall have a current Remote Pilot Certification under title 14 of the Code of Regulations (14 CFR) 107 and meet all Federal Aviation Administration (FAA) requirements. This can be achieved by taking a Commercial Remote Pilot Training course or simply taking the exam at an approved testing center. The fee to schedule an examination is usually around $175. Drones shall be operated under the applicable FAA requirements and the necessary exemptions must be obtained according to the weight of the drone being flown. A Commercial Agricultural Aircraft Operator Certificate shall be obtained if the drone does not meet the requirements for exemption.

The applicator needs to provide the Kansas Department of Agriculture with the make, model, serial number (if applicable) and any other requested information related to the drone and submit a completed and signed application to apply pesticide products. Documentation is needed to confirm that each drone is properly registered with the FAA (FAA registration certificate) and the individual flying it has the proper certification (copy of remote pilot license).  The business making the applications also has to prove they have the proper certification (exemption/rule-making documentation, a Commercial Agricultural Aircraft Certificate) or has obtained the necessary exemptions to KDA.

Commercial pesticide applications via drones or unmanned aerial vehicle are only permitted in the following categories: Category 1: Agricultural Pest Control (1A: Agricultural Plant Pest Control, 1B: Agricultural Animal Pest Control, 1C: Wildlife Damage Control, 1D: Stump Treatment), Category 2: Forest Pest Control, Category 3: Ornamental and Turf Pest Control (3A: Ornamental Pest Control, 3B: Turf Pest Control), Category 5: Aquatic Pest Control, and Category 6: Right-of-Way Pest Control. The individual who is operating the drone during the pesticide application must be a certified applicator in the category that applies to the application. The business need to comply with all existing requirements for obtaining a pesticide business license.

Finally, commercial pesticide applications via drone or unmanned aerial vehicle need to comply with the label requirements of each pesticide product being applied. Remember the label is the law! Unfortunately, though, there is little clear guidance on pesticide labels that pertains to drone applications. One thing to note is that if the label prohibits aerial application then the product cannot be applied by a drone. If aerial application is permitted, the application rate and other parameters need to be in compliance with the label. Also it is important to point out, manufacturers and users are adopting commercial nozzles meant for self-propelled sprayers, which can be a concern for product deposition and coverage.

Insect Heroes of Pollination

By Frannie Miller, Pesticide Safety and IPM Coordinator

All around us, insect superheroes are industriously keeping us fed and our world moving forward whether we take time to notice them or not. Did you realize that pollinators like bees, wasps, butterflies, and bats are responsible for pollinating one out of every three bites of food we eat? The stability of our food supply relies on more than 200,000 species of pollinators. As we celebrate National Pollinator week (June 19-25, 2023), it is a good time to focus on insects which may not get as much glory for providing pollination as those we commonly hear about, like honeybees.

For example, tiny insects called thrips (order Thysanoptera) can play a big role in eating and spreading pollen. Thrips feed on pollen and are quite messy. It is estimated a single thrip can get up to 10 to 50 pollen grains on his body, which does not seem like much, but since they are often present in large numbers that can equate to a lot of pollen movement. These insects fly from plant to plant using the stigma as a landing and take-off point. The pollen is easily transferred from the insect to the stigmas during this process. Thrips are important to the pollination of sugarcane and the mahogany tree, but it is important to point out too many thrips can also cause plant damage and transmit diseases, so their presence is not always wanted.

Hoverflies (order Diptera) also known as flower flies are “incidental” yet prolific pollinators. The adult flies hover over flowers to drink the nectar. Pollen is transferred between the fly and the flower when their hairy bodies brush up against the stigma of the flower. Hoverflies may not carry as much pollen as bees, but they visit the flowers more frequently. These insects prefer small, flat flowers which allow easy access to the nectar, but they do visit a wide variety of our global food crops and flowers.

Hoverfly

For those of us who like eating chocolate, then the chocolate midge (order Diptera) is of extreme importance. These midges seem to be the only creatures which can find their way into the long, twisty, intricate flowers of the Cacao tree to provide pollination. Their pollination duties are most active at dawn and dusk to be in sync with when the flowers are fully open. This pollination allows the prized seed pods to form, which are needed to produce chocolate. Interestingly enough these insects are threatened by clearing cutting of the rain forest as they need the damp rotting leaf litter on the forest floor to thrive.

Chocolate Midge drawing from Insect Art Contest by Lillyon R.

These are just a few examples of the limited knowledge of the true depth of pollinators. In the state of Kansas, it is estimated that there are over 400 different native bee species.

We can help pollinators by growing a diversity of pollinator-friendly plants to help increase the availability of food sources. Check out the publication “Pollinators and Beneficial Insects”(https://bookstore.ksre.ksu.edu/pubs/MF3588.pdf) for a list of possible plants. In celebration of National Pollinator week, consider purchasing one new food or nectar plant to plant in your landscape or doing your own research to identify one lessor known pollinator. You can also place a shallow dish of water on the ground to provide water for pollinators. Help to inform others about the importance of pollinators and inspire them to make a difference!

Feeding Damage to Rose Leaves

From the KSU Entomology Newsletter, article by Raymond Cloyd

We have received numerous inquiries regarding insects feeding on the leaves of rose plants. The insects are sawflies and there are at least two species that attack roses this time of year: the rose slug, Endelomyia aethiops, and the bristly rose slug, Cladius difformis. Rose sawflies are the immature or larval stage, which eventually become a black to yellow adult that resemble wasps. Rose sawfly females create openings or slits along the edges of rose leaves with their saw-like egg laying device (ovipositor) in which eggs are inserted. Larvae emerge (eclose) from the eggs and resemble small slugs. Larvae are approximately 1/2 of an inch long when full-grown and yellow-green, with an orange head.

The larvae will fall onto the soil surface to pupate. Rose sawflies overwinter as pupae in earthen cells created by the larvae. There is typically one generation per year in Kansas. Rose sawfly larvae cause damage by feeding on the underside of rose leaves causing the leaves to appear skeletonized.

 

 

 

Small infestations of rose sawflies are best dealt with by removing the larvae by hand and placing into a container of soapy water. A high pressure water spray will quickly dislodge sawfly larvae from rose plants. Once dislodged the larvae will not crawl back onto rose plants. There are contact insecticides containing various active ingredients that are effective in managing populations of sawflies. Sawflies are not caterpillars.

Consequently, the bacterium, Bacillus thuringiensis subsp. kurstaki, which is the active ingredient in various products (e.g. Dipel®) has no activity on sawflies because the insecticide is only effective against caterpillars.

Webworms Causing Damage to Turf this Spring

Although referred to as the “buffalograss webworm” this insect has the ability to cause damage to cool-season and warm-season turf.  Dr. Raymond Cloyd has had been reached out to help from many in the industry regarding damage to lawns this spring.  Learn more about this insect issue by clicking on the link below and then clicking on Newsletter>2023:

DR. CLOYD’S RECENT K-STATE INSECT NEWSLETTER ARTICLE

Boxwood Leafminer

From the KSU Entomology Newsletter

Figure 1. Boxwood leafminer adult (Joe Boggs, OSU)

The boxwood leafminer, Monarthropalpus flavus, is a major insect pest of the common boxwood, Buxus sempervirens, which is a plant commonly used in landscapes throughout Kansas.

Boxwood leafminer adults emerge (eclose) from pupae when Weigela florida is flowering in the spring. Adults are 1/15 to 1/9 of an inch (2 to 3 millimeters) long, yellow-orange, and resemble mosquitoes or gnats (Figure 1).

Figure 2. Boxwood leafminer larvae (Howard Russell, MSU)

 

 

Adults leave behind pupal cases attached to the leaf after emergence. After mating, females insert eggs inside the tissue of new leaves. A single female lays approximately 29 eggs and then dies afterward.

Larvae emerge (eclose) from the eggs in about three weeks. Larvae are legless maggots, yellow-white to green, and about 1/9 of an inch (3 millimeters) in length (Figure 2).

Figure 3. Boxwood leafminer larvae (Joe Boggs, OSU)

 

 

 

The larvae feed on the leaf tissue inside the leaf (Figure 3). Boxwood leafminer larvae tunnel between the upper and lower parts of leaf tissue creating blotched or irregular-shaped blisters on the lower leaf surface and raised areas on the upper leaf surface.

Learn more about boxwood leafminer and their control in an article by Dr. Raymond Cloyd by clicking HERE.