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Author: Burkholder PHC

What Are Invasive Species?

Invasive species are plants or animals from another region that have been placed in a new environment. Often these species are introduced to an area by humans and can spread quickly and cause damage to native ecosystems and people. While not all invasive species are necessarily dangerous or lethal, some of these plants and animals can disrupt the balance in their new environments.

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Traits of Invasive Species

Invasive species have traits that allow them to thrive and spread over their new environment rapidly. Some of these include

  • Ability to grow quickly
  • Ability to reproduce quickly
  • Ability to disperse a high number of seeds or spores quickly
  • Ability to alter form to suit current conditions
  • Tolerance of a wide range of environmental conditions
  • Ability to sustain a diet of various food types

Invasive species are often overlooked because those unfamiliar with these plants and animals do not perceive them as threatening. However, these plants will take over large areas of land over time. A well-known example of an invasive plant is the kudzu vine (Pueraria lobata). Kudzu was brought from Asia into the United States as a food crop during the late 19th century. The vine spread throughout many southern states in the U.S. and chokes out surrounding plant life.

kudzu covering trees - Invasive species - Burkholder PHC

What Makes Invasive Species Difficult to Control?

Invasive species can be challenging to remove once established. One of the reasons is the lack of natural control mechanisms. In their native environment, plants and animals have predators or environmental factors that act as control mechanisms to keep populations in check.

For example, the spotted lanternfly is an invasive species of planthoppers native to China. In China, the lanternfly is preyed upon by native species of wasps. However, those wasps are not found in Pennsylvania, so the spotted lanternfly has spread rapidly because those predators are unavailable to keep the population in check.

Plants Have Become Established by Being Sold at Nurseries Without Proper Labeling

The most common way invasive plants spread is by being sold at nurseries. In some cases, many invasive plants often lack labeling that indicates whether the plant is native or exotic to a specific region. As a result, governments are taking more action to prevent certain invasive species from being sold at nurseries.

If you are purchasing plants for your landscape, you may wish to check to see whether the plant is native or could have negative impacts on your landscape. If you are concerned about invasive species of plants and insects on your property, contact plant health care experts to assist with removal efforts.

Invasive species are difficult to remove, as removing or controlling their population requires extensive knowledge of the specific species and the various control and removal methods. These methods also have to protect the health of other plants in the environment.

Contact Burkholder PHC for Invasive Species Management

Invasive species can threaten local ecosystems, and some have the potential to cause harm to native wildlife and people. Visit next month as we continue our series and discuss invasive plants. Burkholder PHC has experience helping homeowners in the Main Line area with all types of plants and insects. We have a team of specialists who will visit your property, conduct a plant health care evaluation, diagnose the problems, and inform you of the recommended treatment options. Contact us today for a free consultation.

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Plant Health Care Outlook

The trend of the past 10 years in residential landscapes has been increasing pressure from insect pests, diseases, and vertebrates. We fully expect that this will continue in 2023 and that the plant health care outlook for the next year will include the following conditions.

  1. Increase of insect pest number and variety that will affect more ornamental plants
  2. A wet spring will bring increased soil and foliar disease pressure
  3. Damage from deer will certainly continue to increase for the foreseeable future

In addition, we are just about due for the next invasive landscape pest, following emerald ash borer (1992), brown marmorated stink bug (2001), and spotted lanternfly (2014). Investing in a program to manage the biological health of landscape plants and keep soil in good shape is the best way to ensure your landscape not only survives, but thrives. Burkholder Plant Health Care offers a broad variety of programs to control insects and diseases that are damaging plants, vertebrate pests that are eating investments, and bugs that bite, sting, and transmit diseases to people and pets.

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New Discoveries and Achievements by Burkholder Plant Health Care

Burkholder PHC’s manager, Starker Wright, has been busy in the field. His work, extensive research and education, and his vast experience have led to the following achievements.

  • First identification of crape myrtle bark scale in Pennsylvania (West Chester), confirmed by Penn State Insect ID Lab.
  • Federal quarantine identification of white rust on chrysanthemum (Berwyn), confirmed by USDA-APHIS.
  • First identification of camphor shot borer damage in hemlocks (Phoenixville), confirmed by Penn State Insect ID Lab.
  • First active sampling program in Pennsylvania for vascular streak dieback disease in redbud.
  • Submission of field research article “Pre-Emergent Control of Spotted Lanternfly” in collaboration with Bartlett Tree Experts.
  • Continuing research with Bartlett Tree Experts and University of Maryland on potential impact of native predators on spotted lanternfly eggs.

Burkhoolder PHC Spray Rig - plant health care outlook

Did You Know? Plant Health Care News

On January 10th, Burning Bush (Winged Euonymus, Euonymus alatus) and four species of privet (Japanese, Border, Chinese, and Common) will be added to the list of invasive plants that will no longer be allowed to be grown for sale in Pennsylvania (

These plants will join Callery (Bradford) Pear and Japanese Barberry on the Pennsylvania Controlled Plant and Noxious Weeds List, overseen by the Pennsylvania Department of Agriculture’s Controlled Plant and Noxious Weed Committee (CPNWC). Many other plants are still under consideration to be banned, based on recommendations by the Pennsylvania Governor’s Invasive Species Council (PISC). The current candidate list can be seen at

In Pennsylvania, a noxious plant is “identified as a plant that is determined to be injurious to public health, crops, livestock, agricultural land or other property and cannot be sold, transported, planted, or otherwise propagated in Pennsylvania”.

Every plant that leaves the property of Burkholder Landscaping and Sauder’s Nursery has been proactively monitored and treated to minimize spread insect and disease pests. This does not guarantee that once installed, infestations will not happen, but it does greatly reduce the risk of spreading damaging plant pests.

Contact Burkholder PHC to Improve Your Landscape’s Plant Health Care Outlook for 2023

Now you know what to expect with regard to the plant health care outlook for the coming year, and the information could help you recognize issues in your own yard. Burkholder PHC’s team of experienced, qualified arborists will visit your property, conduct a plant health care evaluation, diagnose the problems, and inform you of the recommended treatment options. In addition, we provide a proactive approach, helping encourage and maintain your trees’ health and appearance. Contact us today for a free consultation.

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Burkholder Plant Health Care Year in Review

2022 was the second full year in the field for Burkholder Plant Health Care. Having a year of local-property data and experience enabled us to measure our successes and adjust our program to address any shortcomings from 2021. As a certified arborist and the manager of Burkholder Plant Health Care, I am taking this opportunity to share with you our plant health care year in review, featuring the top plant health care issues– pests, diseases, and soil conditions — that we regularly addressed on clients’ properties this year.

Following is a list and descriptions of the most common plant health care issues that we saw, results of control efforts, and what we believe is in store for 2023.

6 Pennsylvania Plant Health Care Concerns in 2022

  • Deer

  • Rake in Soil | Plant Health Care by Burkholder Landscape


  • Bagworms
    and Beetles

  • Scale Cottony Maple Scale - Burkholder Plant Health Care- Insects in Landscape Plants


  • square image of boxwood leafminer damage | plant health care year in review | Burkholder PHC


  • Arborvitae

Deer Damage

diagram of trunk with deer rub damage and deterrents | plant health care year in review | Burkholder PHC

Plant damage from deer is a threat to just about every property in this area. In fact, I would confidently say that on unprotected properties, deer inflict more damage (both feeding and antler-rubbing) than any other individual pest: insect, disease, or vertebrate. Damage from deer is exacerbated by the fact that deer target very common feature landscape trees and shrubs and flowering bedding plants. The most effective tool to control deer damage is likely a really good fence. Second is a free-ranging dog, and third is anything else you can throw at them, including deer repellents. Along with multi-component repellents to discourage deer feeding, we have solutions to minimize antler rubbing of trees and to control ticks that are along for the ride. Managing deer is no longer just a winter challenge, and we adjust our program by season and threat level to control deer behavior year-round, with the goal of making our clients’ properties undesirable for deer to visit.

Learn More About Deer Deterrents

Soil Health

Rake in Soil | Burkholder Plant Health Care year in review

Poor Growing Conditions and Soil Diseases

In nature, a rhododendron can live for 100 years or more; however, in residential landscapes, rhododendrons and azaleas can be exceptionally difficult to establish given environmental and pest pressures. In 2022, we found a lot of struggling mature plants whose decline could be traced to specific deficiencies in soil condition, planting site, or planting method.

Effect of Soil pH on Plants

Soil pH is an excellent example of a specific factor that has an inarguable effect on landscape plants, and for the vast majority of common and preferred landscape plants, the ideal pH range leans toward acidic (5.5-6.5). Many common landscape plants require acidic soil; however, of 192 properties on which we have formally analyzed soil chemistry in foundation beds, landscape beds, and beneath featured trees, 165 properties (86%) have a pH above 6.5, meaning that without amendment and adjustment, only 14% of local properties have the basic soil chemistry that supports health and vigor of preferred plants. In general, mature plants that are struggling are growing in compacted or otherwise unhealthy soil with little or no pore space for oxygen and water penetration or buffering of soil chemistry including pH.

Plants need healthy, biologically active, well drained, and well aerated soil to thrive. Fortunately, all of these biotic (soil biology) and abiotic (soil composition, planting techniques, and light/water availability) conditions can be corrected for struggling plants. Using specialized equipment, we can manage soil structure and chemistry, root physiology, and environmental stress to restore plant health, vigor, and aesthetic value.

Soil Diseases

A majority of landscapes in this area are supported by unhealthy soil. In addition to shortcomings in structure and chemistry, challenged soils are highly prone to harbor soil-borne plant diseases such as phytophthora root rot and black root rot, lethal diseases that colonize and kill the roots of many ornamental plants, starving the plants of water and nutrients. We have a very effective, integrated strategy to manage this disease, beginning with on-site testing and chemical analysis to confirm presence of the diseases, followed by multi-tactic chemical and physical treatment of soil and affected plants. Our team is trained to detect this disease before damage is irreversible, confirm diagnosis, and apply specific treatments to restore the function of the root system.

Learn More About Soil Health

Bagworms and Beetles

Rake in Soil | Plant Health Care by Burkholder Landscape

Bagworm and Japanese Beetle

In late June each year, two insect pests emerge and can devastate certain groups of landscape plants: bagworm and Japanese beetle. Both of these pests can destroy the aesthetics of valuable landscape plants very quickly, and the greatest difficulty with both is the fact that when damage is apparent, it is too late to contain. In other words, management tactics must be in place before the peak population of the pest is actively feeding to ensure an acceptable level of damage control. Our team is trained to identify and treat for bagworm and Japanese beetle before damage is apparent, and our IPM program (Integrated Pest Management program) is structured to facilitate management of annual pests like bagworm and Japanese beetle before they become a problem.

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Scale Insects

Scale Cottony Maple Scale - Burkholder Plant Health Care- Insects in Landscape Plants

Scale insects continue to be the most prolific group of insects feeding on and damaging local landscape plants. Individuals of this diverse group of insects attach to various plant parts and feed on the vascular system of the plant, capturing and digesting nutrients as sap moves between the leaves and roots. Scale insects can build to astounding numbers on some plants. Of this group, the most important pests are currently

  • White peach/prunicola scale
  • Japanese maple scale
  • Cottony camellia (taxus) scale

However, scale insects are affecting more plant species every year, and a majority of landscape plant species have one or more species of scale insects that feed on them and can cause significant damage. In fact, last year we were able to identify the first infestation of crape myrtle bark scale in the state of Pennsylvania and have since identified and treated this pest on dozens of properties. Our IPM program provides each of our clients’ properties with professional evaluations to determine throughout the year if plants are currently infested with or at risk of infestation with insidious scale insects, allowing treatment and control before the plants are damaged beyond repair.

Learn More About Scale Insects

Boxwood Leafminer

boxwood leafminer damage | plant health care year in review | Burkholder PHC

Leafminer is the most destructive insect pest of boxwood. These are fly larvae and they feed between layers of leaves, creating patchy discoloration on the tops of the leaves and light-colored blisters on the lower surface. Leaves are eventually killed by the feeding of the larvae and turn brown, destroying the aesthetics of the plants. Proactive treatment of boxwood leafminer is critical to bringing this pest under control and protecting boxwoods, which are often the most highly featured and valuable plant installations on residential properties. Management of boxwood leafminer requires accurate diagnosis and precise timing of treatment to coincide with vulnerable growth stages of the insect, without collateral damage to beneficial insects such as honeybees and other pollinators. This season, we worked on 97 properties with featured boxwoods (10+ plants), and boxwood leafminer was detected on 80% of these properties (78 of 97).

Learn More About Boxwood Issues

Arborvitae Borers

Scale Cottony Maple Scale - Burkholder Plant Health Care- Insects in Landscape Plants

Arborvitae (especially Green Giant and Emerald Green) are among the most common landscape trees in this area. Historically, these have also been among the most durable and reliable landscape plants, fast-growing, consistent shape and size, and relatively insect and disease resistant. From our experience, there are only four common problems with arborvitae in general: deer browse, bagworm, phytophthora root rot, and wind/snow/ice damage. In 2021, we started to see damaged arborvitae in nurseries: trees with individual flagging limbs: dull green-gray branches that turn brown and shed their foliage. On trunks and limbs of these damaged trees, we found a particular species of bark beetle (shothole borer)—tiny beetles whose larvae tunnel just beneath the bark and can kill branches. When there are enough beetles in a tree, they can kill large sections, eventually leading to tree death. In 2022, we observed much more damage from this pest particularly in newly installed trees, and further examination revealed that it is most likely that trees were being infested and damaged immediately after planting. Trees stressed by transplanting conditions produce ethanol, and beetles in surrounding woods are attracted to the odor of these trees, quickly colonizing and damaging branches in as little as 6 weeks after planting. Our program has adapted to manage this risk, preventatively treating transplanted arborvitae after installation, monitoring for early indications of infestation, and nurturing new trees to full health and vigor to reduce likelihood of damage using the trees’ own defensive mechanisms.

Learn More About Arborvitae Issues

Contact Burkholder PHC for Exceptional Treatment of Plant Care Issues

Burkholder PHC has a team of experienced, qualified arborists who will visit your property, conduct a plant health care evaluation, diagnose the problems, and inform you of the recommended treatment options. In addition, we provide a proactive approach, helping encourage and maintain your trees’ health and appearance. 

If you are a current or past client of Burkholder Plant Health Care, thank you for trusting us with the care of the structure and biology of your landscape plants. If you have not brought our services onto your property and are interested in an assessment of the condition of your landscape plants, just let me know ( All of our initial evaluations, sampling, and diagnostics are free for current or past clients of Burkholder Brothers. For more information about the Burkholder Plant Health Care Year in Review, give us a call.

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Mosquitoes have long been considered summertime pests. You know that mosquitoes are annoying with their high-pitched buzzing on hot summer nights, and that their bites lead to itchy skin. Did you know that these insects pose health risks to animals and people? Mosquitoes are actually a major risk to human and animal health. Mosquito borne diseases are spread through their bites, which can cause sickness and death in both humans and animals.

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Mosquito Bites

Bites from mosquitoes cause itchy skin and welts in most humans, resulting from the immune system releasing histamine when the mosquito breaks the skin. Though mosquitoes consume nectar for energy to fly, females need a blood meal to nourish developing eggs. These female mosquitoes are attracted by carbon dioxide, so humans and animals are perfect targets. Mosquitoes are also likely to fly in groups, so a person can receive multiple bites in a short time.

The Risks Mosquitoes Carry

These pests carry numerous risks for humans and animals during their active times. They are typically not active when temperatures drop below 50 degrees.

Mosquito Risk to Human Health

Mosquitoes are a risk to human health in the United States, particularly during the summer months. The Centers for Disease Control and Prevention (CDC) reports that there are about 3,000 deaths in the United States each year from mosquito-borne diseases, including:

  • Zika virus
  • West Nile virus
  • Eastern equine encephalitis

golden dog-risks of mosquitos to animal health - Burkholder PHC

Mosquito Risk to Animal Health

With their fur, you might think that animals would be protected from mosquito bites. However, they are at risk of health problems from mosquito bites too. Mosquitoes transmit heartworm disease, which can be fatal to dogs, cats and horses.

You can protect your animals in a few ways:

  1. Use a heartworm preventative that kills mosquitoes. The heartworm preventative you use also kills other blood-feeding insects such as ticks and fleas.
  2. Keep your pet indoors at dawn and dusk when mosquitoes are most active.

Use insect repellents for dogs such as spot-on treatments (Frontline Shield, Advantix II) or natural sprays (Wondercide, Vet’s Best). Repellents intended for humans (especially those containing DEET) are not recommended for use on animals.

The best way to prevent these diseases is to reduce the number of mosquitoes in your landscape using Integrated Pest Management (IPM).

Learn About Integrated Pest Management

How Integrated Pest Management Helps

Integrated Pest Management (IPM) is a pest management strategy that combines common-sense practices and ecological concepts to reduce pest populations. These practices include:

  • Pesticide application when necessary
  • Prevention of pests by exclusion, sanitation, and other non-chemical means; and if pesticides are used, choosing the least toxic one for the situation at hand
  • Monitoring for insect population trends so appropriate pesticides can be applied only when needed

IPM’s holistic plant health care and pest management helps create and maintain conditions ideal for a landscape’s health and minimize pests’ presence and effect.

Mosquito Management

What are the ways to treat mosquitoes in your landscape?


Plant health care professionals may use insecticides to treat pests in a home landscape. Insecticides are most effective against immature mosquitoes when applied to areas where water collects, such as around the foundation of a house and near fish ponds or birdbaths that hold water for long periods. For control of adult mosquitoes, we recommend treatment of mosquito resting and mating sites (such as plant material) up to 6 feet high around the boundary of a property or landscape feature such as a deck, patio, or pool. For consistent control of adult mosquitoes, treatments should be reapplied monthly through the peak season of mosquito activity.


Repellents can be sprayed on plants as a preventive measure against mosquitoes.

Biological Controls

Some natural predators feed on mosquito larvae in water bodies, including dragonflies, damselflies, and backswimmers. Unfortunately, these predators fail to survive long enough after hatching to effectively control populations for more than one generation unless abundant food is available for them all year round. Each generation of mosquito adults generally only mates once, and males die within about 2 weeks of mating. Females can live for a month or more, may lay up to 10 batches of eggs (50 to 500 per batch), and will continue to feed on blood throughout their lives.


You can also use barriers like mesh screens across doorways leading outside or window screens over windows that open onto balconies or porches where people spend time outdoors during evenings. The barriers can help keep pests from entering your house.

Eliminating Standing Water

Eliminating standing water is an effective method of reducing mosquito populations since water is required for mosquito eggs to hatch. This practice is referred to as source reduction. Examples include old tires, buckets, flower vases, abandoned toys, and other items that collect rainwater in shady areas of your yard. If you have a pool or pond in your yard, ensure proper maintenance to prevent algae and mosquito-friendly plants such as cattails from growing.

Contact Burkholder PHC for Treatment of Mosquitoes and Other Pests of Human Health

Mosquitoes can pose significant risks to human health. We would recommend a professional evaluation to determine if your property is infested with or at risk of infestation with these pests. Our evaluation is free, and proper treatments can restore your landscape’s health. Contact Burkholder PHC today for a free consultation.

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What is Corrective Pruning?

Corrective pruning is a technique meant to maintain or enhance a tree’s health by removing dead, diseased, weak, or otherwise unhealthy or unsafe branches. Corrective pruning can be beneficial to both the tree or shrub as well as the landscape as a whole.

See Our Pruning Before and After Gallery

Benefits of Corrective Pruning

The main benefit of corrective pruning is that your tree will be healthier and more attractive. You can also reshape your tree’s canopy if you have accidentally allowed the structure to become too dense or if you want to create a more open look.

Improving the Health of the Tree

Removing dead or diseased wood allows light and nutrients to reach healthy parts of the tree. Diseased wood can be treated with an appropriate fungicide if necessary. Pruning can also help thin out a canopy which is sometimes necessary to allow more sunlight and air circulation. One reason is that too many branches close together means more competition among branches for sunlight, and as can often happen, some limbs will get more sunlight at the expense of others. Overly dense branches can make it difficult for certain stems to properly absorb enough rainwater or air to circulate within the canopy.

Viburnum Pruning Before Corrective pruning | Burkholder PHC
Viburnum Pruning After Corrective pruning | Burkholder PHC

Increasing Tree Safety

Trees can be afflicted by many issues that weaken the structural integrity of the tree, which increases the risk of branches (or the entire tree in severe cases) falling or breaking off to damage whatever is below or beside them. For example, many tree species are prone to developing codominant stems, where a tree has two trunks that are similar in diameter. Think of a tree whose trunk splits and forms a Y-shape. In this instance, both codominant stems compete, creating a weak upper structure and likely breaking apart in harsh weather conditions.

Pruning back branches that are growing too low down on a trunk helps prevent damage from snow and ice, which can break off large portions of bark in winter storms if they are close enough to ground level. Vulnerable branches at any height can break off without warning and damage property or persons beneath.

In the case of codominant stems, a certified arborist can prune one of the stems, reducing or removing segments or entire branches, so any new growth occurs around a single, strong trunk. Arborists can selectively prune branches to create a more stable, safe, and healthier tree.

Holly Before Reduction Pruning | Burkholder PHC
Holly After Reduction Pruning | Burkholder PHC

Improving the Aesthetics of Your Landscape

Reducing long limbs that are difficult to reach and eliminating unsightly growth at the base of a tree will enhance the beauty of your landscape.

Why You Should Hire a Professional Arborist for Pruning

Corrective pruning is a far more complex process than simply cutting off tree branches. Therefore hiring a professional certified arborist is recommended.

  • The tools need to be adequately cleaned to prevent further spreading or introduction of new diseases.
  • Specific tools are required to prune trees correctly.
  • Pruning requires carefully examining branches and making exact, precise cuts to maintain a tree’s health as much as possible.

For the best results for your trees and to ensure safety, having a licensed and insured tree specialist perform the work is the best decision.

Contact Burkholder PHC for Corrective Pruning & Other Tree Services

If you believe that your trees need corrective pruning, send us an email or give us a call. Burkholder PHC has a team of experienced, qualified arborists who will visit your property, conduct a plant health care evaluation, diagnose the problems, and inform you of the recommended treatment options. In addition, we provide a proactive approach, helping encourage and maintain your trees’ health and appearance. Contact us today for a free consultation.

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What Are Growth Regulators?

Growth regulators are a group of chemicals used to modify the various growth processes in plants. These chemicals help with many issues in a plant’s lifecycle, including suppressing vegetative growth and stimulating flowering, controlling plant height, enhancing plant branching, and enabling plants to flower during short-day conditions (during late fall and winter). The chemicals used can be found inside plants already but are sometimes modified to improve or lower their efficiency and modify specific processes.

Learn About Plant Growth Regulator Treatments

Plant growth regulators are sometimes referred to as plant hormones because the chemicals act similarly to human hormones. Hormones are chemical messengers that affect your body’s growth, metabolism, and more, the same role that regulators play for plants. Regulators are absorbed by plants via roots, foliage, or by absorption into sapwood and “tell” the plant when it is time for them to grow, flower, or enter a state of dormancy. These chemicals are slow-acting and can take weeks to affect a plant.

While growth regulators can be used to prevent plants or trees from growing, these hormones differ from herbicides. Herbicides quickly kill all the vegetation with which the substances come in contact. These regulators limit the number of nutrients a plant uses, so the plant grows slowly.

Types of Growth Regulators

Plant growth regulators can be broken down into two main types, with specific chemicals falling under one or the other:

  • Promoters enhance and stimulate cell division, plant cell enlargement, flowering, fruiting, and seed formation.
  • Inhibitors prevent growth and promote dormancy and abscission (shedding) in plants.

Examples of promoters include auxins, gibberellins, and cytokinins. An example of an inhibitor is abscisic acid. Each of these growth regulators affects specific processes within plants.


Auxins are hormones found in shoot and root tips that promote cell division and stem and root growth. This chemical is used to help stimulate cell elongation by increasing cell walls, thus helping promote the plant’s stem growth. Auxins can also drastically affect plant orientation by promoting cell division to one side of the plant in response to sunlight and gravity. Plants grow in the direction necessary to absorb the most sunlight possible, so if sunlight only shines on the western side of a plant, auxin will collect on the shady eastern side to promote growth.

Person applying chemical to plants | what are growth regulators | Burkholder PHC


Gibberellins affect many aspects and processes within a plant, such as germination, flowering, and flower development. One of the uses of gibberellins in plant health care is growth and germination control. Low hormone concentrations can increase the speed of germination and stimulate cell elongation, so plants grow taller.


Like auxins, cytokinins are chemicals that promote cell division and the formation of new leaves. Generally, cytokinins help initiate flower budding and encourage lateral growth so that a plant becomes “bushier,” or more expansive in size. In addition, if a plant has increased absorption of water and other minerals, then cytokinins can help stimulate the metabolism of young shoot cells, encouraging growth.

Abscisic Acid

Unlike the plant growth regulators mentioned above, abscisic acid is an inhibitor, slowing down growth, metabolism, and seed germination. In addition, abscisic acid helps regulate dormancy and shedding, particularly as a response to environmental conditions and stresses, such as droughts or extreme temperatures. The chemical also plays a vital role in increasing stress tolerance and generally improving a plant’s ability to respond to stress.


While ethylene can inhibit plant growth, this chemical is sometimes used as a promoter. Like abscisic acid, ethylene promotes leaf and flower shedding but can also be used to break the dormancy of seeds and promote flower bloom.

The Importance of Growth Regulators

As mentioned above, each of these plant growth regulators affects different aspects of plant growth and development, and each is needed in different amounts based on the conditions and issues a plant faces. For example, if a plant is too short, a certified arborist or plant health care expert can provide concentrations of gibberellins to promote growth and help make the plant taller. Likewise, if a flower needs help blooming, a plant health care specialist can use chemicals such as cytokinins or ethylene to encourage blooming. All of these hormones and chemicals can be used to help plants grow in a particular way while maintaining the plant’s overall health and biology.

Contact Burkholder PHC for Plant Care Services

If you want to keep your plants and trees healthy and vibrant, contact Burkholder PHC. We offer many plant health care services, such as plant growth regulators, pest control, and soil care. In addition, our team of specialists has years of experience maintaining landscapes in the Main Line area. For more information about our services, request a free consultation today.

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What is Phytophthora Root Rot?

Phytophthora root rot is a common fungal disease that afflicts many plants outdoors and indoors. The condition causes rotting within the plant stem and roots. Young plants are particularly prone to the adverse effects of the disease, but many plants, trees and shrubs can be affected. This article will focus on the causes, symptoms, and potential remedies that may help treat the root rot.

Learn Signs Of Plant Stress

What Causes Phytophthora Root Rot

Phytophthora is a genus of parasitic microorganisms that cause a range of diseases in plants, particularly in the roots. The genus includes about 140 species. They are oomycetes, as are all water molds, and like other members of this group they have microscopic sporangia (spore capsules) that are produced in great numbers by germination of endospores. Certain conditions are more conducive to disease development, namely if the soil contains too much moisture and if the soil temperature is above 60 degrees Fahrenheit. In these conditions, oospores germinate and produce additional spores. These spores then infect a plant’s root and rot the system over time. More spores form in the residue, and the entire cycle repeats, infecting other plants.

What does Phytophthora Root Rot look like?

Some of the standard and most visible symptoms of Phytophthora root rot include the following:

  • Leaves that turn dull green, yellow, or in some cases, red or purple
  • Dark brown or black discoloration of the stem that extends up from the root/soil line
  • General wilting of the leaves and branches

Other symptoms depend on the plant that is infected. Trees, for example, can have dark sap oozing from the trunk. Another symptom is reddish-brown streaks in the bark tissue. Signs of the disease can also appear on single leaves or branches of a tree and then spread to others.

    Wilting phytophthora rot on a Rhododendron | Phytophthora Root Rot | Burkholder PHC

    • Phytophthora rot on a pine tree | Phytophthora Root Rot | Burkholder PHC

      Pine Tree

    • Phytophthora rot on an Arborvitae | Phytophthora Root Rot | Burkholder PHC


    • Phytophthora rot on Cryptomeria | Phytophthora Root Rot | Burkholder PHC


    • Phytophthora rot on a maple tree | Phytophthora Root Rot | Burkholder PHC


    How Do I Get Rid of Phytophthora Root Rot?

    Water and drainage are among the most important factors when managing or preventing Phytophthora root rot. First, plants need the correct amount of water, as overwatering (to the point of creating standing water around the base of trees or other plants) facilitates growth of this fungal disease. Second, proper drainage, which can be accomplished by breaking up compacted soil, is necessary to prevent excessive moisture in the soil.

    Chemical controls can also be used in conjunction with water and drainage management. Fungicides need to be applied carefully and with professional guidance to maintain the health of other plants and the overall landscape. Another factor to consider is removing the infected plant. Removing an infected plant may be necessary to prevent the disease from spreading to other plants nearby. This is best done in winter since oospores prefer warm temperatures and are less likely to infect other plants.

    What Plants Are Resistant to Phytophthora Root Rot?

    If you are considering planting new plants in your landscape, we advise you to choose plants resistant to Phytophthora root rot. Below are 3 plants that are resistant to the fungal disease and native to Pennsylvania:

    • Summersweet (also known as “Tom’s Compact Summersweet) a compact variety of flowering shrub that produces upright, candle-like, 6-inch-long white flower spires in summer.
    • Sweetspire – a rounded, spreading, fragrant shrub with drooping spires of fragrant white flowers.
    • Eastern ninebark – a deciduous shrub that grows 6 to 10 feet tall and wide, with green leaves 1 to 3 inches long. Small, pink-white flowers bloom in spring and red fruits appear in fall.

    By planting flowers that are resistant to this fungal disease, you can prevent your landscapes from ever being afflicted.

    Contact Burkholder PHC for Plant Health Care Services

    If your plants show symptoms of Phytophthora root rot or other diseases, contact Burkholder PHC. Our team of experienced, qualified plant health care experts will evaluate the health and condition of your plants, diagnose the problems, and provide you with the recommended treatment options to keep your plants healthy and vibrant. Our proactive and holistic approach helps encourage and maintain the conditions that are best for your landscape. Contact us today for a free consultation.

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    Crape Myrtle Bark Scale, a New Pest in Pennsylvania Landscapes

    In May of 2021, we began seeing darkened stems and black moldy growth on crape myrtles in Chester County, carrying over from an insect infestation in the fall of 2020. To recognize that these symptoms were not caused by crape myrtle aphids (common), samples were collected and submitted to the Insect Diagnostic Laboratory at Penn State. These samples revealed the first recorded incidence of crape myrtle bark scale (CMBS) in the state of Pennsylvania. This spring, calls regarding damaged crape myrtles have become much more common, and diagnosis is almost always this insect, which we have now also found in Delaware County. This is bad news for Pennsylvania’s crape myrtles, one of the most ubiquitous and attractive flowering plants in the landscape.

    View Our Plant Stress Tool

    How Crape Myrtle Bark Scale Came to Pennsylvania

    Crape myrtle bark scale is an invasive insect introduced to the United States from Asia in the early 2000s. The insect was initially collected and confirmed near Dallas, Texas in 2004, and detections have slowly moved eastward across southern states, with detection in Arkansas in 2013, North Carolina in 2018, and Maryland in 2020. This insect has been detected in 18 states (including DC), and the Pennsylvania infestation is the northernmost detection to date.

    Initial models suggested that this insect would not move north of USDA Growing Region/Plant Hardiness Zone 8 (coastal Virginia and North Carolina); however, the Philadelphia area is precisely aligned with Beijing, China (~40o N Latitude), which is the northernmost range of this insect in its native land. Likely, this pest can survive in any geographic region where crape myrtles are a realistic landscape option; as winter hardiness is bred into crape myrtles, both the plant and the bug will move further north. In general, low temperatures will kill the tree before killing the pest, which can survive through winter at any life stage, from egg to adult.

    Magnified branch tip with crape myrtle bark scale | Burkholder PHC

    The Damage Crape Myrtle Bark Scale Causes

    Leaves infested with crape myrtle bark scale | Burkholder PHC

    Crape myrtle bark scale (CMBS) is a serious, direct, and primary pest of crape myrtles; however, an infestation of this pest alone will rarely kill trees outright. Instead, damage to crape myrtles is most commonly seen as the development of black sooty mold on the bark and leaves of the tree, and black sooty mold is just what it sounds like: a gray to black moldy growth covering leaves and bark.

    Aside from the aesthetic problems of having ornamental trees turn black, heavy infestation with CMBS will delay foliar emergence (leaf-out) in spring and can severely limit flower growth (up to 70% loss of blossoms). In addition, the black sooty mold is growing on the insect’s excrement, which is very high in sugars and commonly attracts masses of unwelcome stinging insects such as wasps and hornets. This phenomenon is similar to what one sees locally, accompanying high infestations of spotted lanternflies on maples, willows, styrax, and ailanthus.

    Identifying Infestation

    Trees suspected of infestation by Crape Myrtle Bark Scale can be confirmed quickly since this scale is the only bark scale active on crape myrtles and is one of only two direct pests that produce black sooty mold on these trees.

    The most common symptom of an infestation is a general darkening of the bark, which can be seen in spring, especially when infested trees are close to uninfested trees. Closer examination will reveal clusters of white bumps or tufts, which are the silken sacs that the bugs have spun to either:

    • Lay eggs in and die (adult females), or
    • Protect themselves during metamorphosis (males)

    Looking even closer, the individual insects (eggs, nymphs, pupae, and adults) are bright pink, and smashing the white silken bumps with a fingernail produces a blob of dark pink goo.

    crape myrtle with leaf drop due to crape myrtle bark scale | Burkholder PHC

    • Entire tree infested with crape myrtle bark scale | Burkholder PHC

    • Tree with middle branch infested with crape myrtle bark scale | Burkholder PHC

    • Tree with outer branch infested with crape myrtle bark scale | Burkholder PHC

    With large numbers of CMBS, the presence of these insects on trees is very clear; however, with newer or smaller infestations, most signs will be seen in the following:

    1. At pruning cuts
    2. In branch unions
    3. On the underside of upper branches

    A correlation between trees growing in the shade and more significant CMBS damage has been found, meaning that trees in full sun are either less prone to infestation or damage is less pronounced in full-sun trees. According to preliminary data taken in Texas, significant differences exist in the rate or density of infestation by various crape myrtle. The data found no varieties to be resistant to CMBS. However, some were worse than others, and CMBS has been found to infest all types of crape myrtle available in USDA Zone 6 (most of Pennsylvania).

    Life Cycle of the Crape Myrtle Bark Scale

    Through most of the range of CMBS in the United States, this insect has 2-3 generations per year, and in the northern edge of the known range (Pennsylvania), the hypothesis is that only 1-2 generations will form, given the shorter growing season. Each generation takes 3-4 months to complete development (from adult to adult). However, the number of generations in any particular area can be challenging to determine since all life stages are capable of overwintering.

    Newly hatched eggs (for scale insects, this stage is known as crawlers) are the most mobile and most vulnerable life stage. Therefore, most chemical control products recommend treatment to coincide with egg hatch/crawler activity. Eggs are most likely to hatch after about 10 days at or near 80oF, and in the Philadelphia area, we expect that egg hatch will occur in late May or early June (~650-750 degree days).

    Section of Tree with Crape Myrtle bark scale | Burkholder PHC
    Crape Myrtles with symptoms of crape myrtle bark scale indicated } Burkholder PHC

    What Plants Are Affected

    In its native range (China, Japan, and Korea), CMBS has reported many plants of economic importance, including apple, soybean, blackberry, and Korean boxwood. However, this pest is most associated in Asia with crape myrtle, persimmon, and pomegranate. In trials done in the US, CMBS has been found on 5 plants reported from Asia, aside from crape myrtle. Plants on which CMBS has been found in the US include St. John’s wort, American beautyberry, and recently spirea.

    Treatment for Crape Myrtle Bark Scale

    With invasive pests of landscape plants, population levels and damage can be explosive, and early detection is the key to effective management. Many strategies are available to manage this insect pest, from biological control agents (releasing of the pest’s natural enemies, ladybugs) to chemical controls (systemic insecticides or topical treatments). However, none will be as effective as is possible with the identification of the problem before damage becomes irreversible.

    Contact Burkholder PHC for Treatment of Scale Insects in Landscape Plants

    Crape Myrtle Bark Scale can be challenging to control due to their behavior and physiology. If crape myrtles are a signature species of your landscape, or if you have trees that appear to be declining, send us an email or give us a call and we will come out and conduct a plant health care evaluation, diagnose the problems, and let you know what your treatment options are. Burkholder PHC provides no cost identification of the problem in addition to free testing, diagnostics, inspections, and evaluations. Contact us today for a free consultation.

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    Scale Insects in Landscape Plants

    There is consensus among plant health care professionals that the complex of insect and disease pests in landscape plants is becoming more explosive, harder to predict, and more difficult to manage. As invasive pests like Asian longhorn beetle (1998), brown marmorated stink bug (1998), emerald ash borer (2002), and spotted lanternfly (2014) have been brought in through the back door of global trade, attention has been drawn away from many old-school native pest groups, allowing some to catch a foothold in landscape plants and become increasingly problematic. No landscape plant pests have expanded more in the past decade than scale insects, which have historically been kept in check by biological control agents (predators and parasites), kept at low levels by weather factors, or controlled by collateral effects of treatments targeting other pests. In fact, advances in the technology of pest control may be partially responsible for the increasing threat from this pest group, as fewer systemic and broad-spectrum chemicals are used for non-selective pest management in landscape plants.

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    Scale insects are an extremely broad and diverse group, made up of two basic subgroups: soft scale and hardshell scale (armored scale). Soft scales are fairly large (visible to the naked eye) and secrete sugary honeydew that forms black mold on the infested plant along with anything beneath. These insects may look like small bumps on twigs and stems and are most commonly located and identified because of the amount of mold that grows on their excrement, turning plants black. Armored scale are much smaller, often not visible to the naked eye, and generally shaped like tiny oysters. Armored scale are most commonly located and identified because of decline/dieback of individual limbs or white, waxy powder on interior stems. Scale insects do not move very much and spend most of their life securely attached to the plant like a tick or a barnacle. All species of scale insects feed on the vascular system of the plants, intercepting critical nutrients moving between leaves and roots, leading to rapid decline of the infested plant.

    A majority of common landscape plant species have one or more species of scale insects that feed on them and can cause significant damage; in the 2021 field season, we identified and treated 18 species of scale on properties in Chester, Delaware, and Montgomery counties.

    Plant Species Soft Scale Armored Scale
    Azalea Cottony Azalea Scale
    Azalea Bark Scale
    Cherry Laurel/Skip Laurel

    White Peach/Prunicola Scale

    Euonymus (Burning Bush)

    Euonymus Scale
    Japanese Maple Scale

    Holly Cottony Camellia (Taxus) Scale

    White Peach/Prunicola Scale
    Japanese Maple Scale

    Rhododendron Cottony Azalea Scale

    Cottony Camellia (Taxus)
    Scale Fletcher Scale

    Viburnum Cottony Camellia (Taxus) Scale

    Oystershell Scale

    Arborvitae Fletcher Scale
    Pieris Azalea Bark Scale

    Maskell Scale

    Dogwood Cottony Maple Scale

    Japanese Maple Scale

    Redbud Lecanium Scale
    Crape Myrtle Crape Myrtle Bark Scale

    White Peach/Prunicola Scale

    Magnolia Magnolia Scale

    Fiorina/Hemlock Elongate Scale

    Spruce Spruce Bud Scale
    Witch Hazel Cottony Camellia (Taxus) Scale
    Japanese Maple

    Japanese Maple Scale

    Hybrid Elm/Zelkova European Elm Scale

    Japanese Maple Scale

    • Azalea Bark Scale

    • Azalea Bark Scale

    • Cottony Azalea Scale

    • Cottony Camelia Scale

    • Cottony Maple Scale

    • Crape Myrtle Bark Scale

    • Crape Myrtle Bark Scale

    • Elongate Hemlock Scale

    • Euonymus Scale

    • European Elm Scale

    • Fletcher Scale

    • Japanese Maple Scale

    • Lecanium Scale

    • Lecanium Scale

    • Lecanium Scale

    • Magnolia Scale

    • Magnolia Scale

    • Maskell Scale

    • Maskell Scale

    • Oystershell Scale

    • Spruce Bud Scale

    • White Prunicola Scale

    • White Prunicola Scale

    • White Prunicola Scale

    So…what can be done about scale insects in landscape plants? As with all of our integrated pest management (IPM) programs:

    1. Inspect and diagnose to determine which pest species is causing the problem.
    2. Assess the extent of the damage.
    3. Determine the need for intervention.
    4. Apply least-damaging control measures.
    5. Evaluate results and determine the need for follow-up treatment.

    With scale insects, there are challenges at each of these steps, from identification of the pest responsible to recognizing an array of plant injury symptoms and from determining the need for intervention to understanding what management tactics will provide the greatest control at the time of application.

    Contact Burkholder PHC for Treatment of Scale Insects in Landscape Plants

    Although scale insects are a very odd and very primitive group of pests, their behavior and physiology can make them very hard to control, prone to explosive population growth, and very damaging to landscape plants. We would recommend a professional evaluation this winter and spring to determine if properties are currently infested with or at risk of infestation with scale or other pests. The evaluation is free…and proper treatments can bring back the health, vigor, and curb appeal of any landscape. If you are not happy with the appearance of your landscape plants, give us a call!

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