Category: woody plants

Plant Detective: Identifying Fungal Rust on Eastern Redcedar

On By durhammastergardenersIn plant disease, plant fungi, Uncategorized, woody plants

By Wendy Diaz, NC State Extension Master GardenerSM volunteer of Durham County

Evidence of Cedar-Quince Rust on Eastern Redcedar (Juniperus virginiana)

I noticed a bright orange coating on the peeling bark of the branches and trunk of an Eastern Redcedar shrub (Juniperus virginiana) along my backyard property boundary during a routine walk around my yard in the early spring last year.

Orange swellings between peeling and on bark of Eastern Redcedar branch on March 13, 2025. (Image credit: Wendy Diaz)

Many years ago, I transplanted it along with several other volunteer Eastern Redcedar seedlings, to create a windbreak and evergreen screen when the hardwood forest behind our property was developed into a subdivision. I knew at the time it wasn’t an ideal location for these sun-loving natives[1]; under the shade of a large White Oak but they did survive and slowly grew from 4 inches to several feet high. 

View of backyard Eastern Redcedar hedge. Area circled in red denotes the diseased cedar shrub planted behind the white oak tree which was diseased and later removed. (Image credit: Wendy Diaz)

The Eastern Redcedar with the orange coating was located in the most-shaded part of the hedge and behind the oak, so it was no surprise to me that it developed a disease at this location. There are three different rust fungus that can infect Eastern Redcedar: 1. Gymnosporangium juniperi-virginianae[2] which produces bright orange gelatinous galls with tendril-like protrusions or Cedar-Apple Rust (spores from these galls will infect apple trees). 2. Gymnosporangium globosum smaller, less conspicuous branch galls, with horn-like protrusions or Hawthorne Rust and, 3. Gymnosporangium clavipes or Quince rust (spores infect rosaceae plants). I did not observe round branch galls[3] so I concluded Cedar-Quince rust was the disease on my cedar shrub which is caused by the Gymnosporangium globosum fungus[4].

Close up of Cedar-Quince Rust on branch of Eastern Redcedar on March 13, 2025. (Image credit: Wendy Diaz)

Disease Cycle

These fungi need plants from two plant families to complete their life cycle (multiple hosts).[5]  Of the rust diseases, Cedar-Quince has the broadest host range and affects many genera of the Rosaceae family including apple, crabapple, flowering quince, hawthorn, serviceberry and mountain ash.[6] In damp spring weather it forms orange, gelatinous blisters on the bark of branches of the Eastern Redcedar. It can kill young branches and weaken plants when the cankers develop on the main trunk. When it infects the other hosts, like apple, it infects the young branches and fruit but not the leaves. Basidiospores released from the Eastern Redcedar branch orange swellings will infect the stems and fruit of quince and other deciduous host plants. Seven to ten days after infection spots develop, followed by the formation of tiny black dots within the spots a few days later. Globular or cup-shaped structures (aecia) are formed four to seven weeks later. Aecipospores, which are released during a rain event from these structures, will become airborne and infect susceptible Easter Redcedar plants during late summer or fall. One year later, swellings composed of both fungal and host plant tissues will develop on the Eastern Redcedar host. When the spring weather is wet and cool (74 to 78 degrees F) swelling on the branches of the Eastern Redcedar will result in the release of basidiospores which in turn will infect quince or another deciduous host, and the cycle continues.

Management of Cedar-Quince Rust on Eastern Redcedar

Pruning and proper disposal of the infected branches, if practical, is a good way to control the disease. I decided to remove the thinly branched Eastern Redcedar and burn it because it had lost it ornamental value and it was unhealthy and the other cedars beside it did not appear to be infected. Because two kinds of plants are necessary for the survival of this fungus, removal of my old flowering quince in my front yard that has developed galls seems to be a practical solution for me because I want to eventually remove most of my non-native species in my yard.[7]

There are preventive fungicides that are made to protect developing/new growth twigs and branches from infection during the time the swellings on the Eastern Redcedar are orange and gelatinous. Multiple applications over several weeks are necessary until the orange coating becomes dry and inactive. Pesticides registered for use include: captan, chlorothalonil, mancozeb, sulfur, thiram and ziram. Other strategies include not planting susceptible host plants within a few hundred yards of apples, hawthorns and other plants of the Rosaceae family. Other cultural methods of disease control would be planting plants that are resistant to rust diseases and removing galls from the deciduous host plants to reduce infection of the alternate host plant. The gall is not as big as the black knot disease[8].

Black gall on the flowering quince on Febraury 24, 2025. The gall is not as big as those associated with black knot disease.8 (Image credit: Wendy Diaz)

This experience was a reminder to me to take a stroll and inspect parts of my yard that I have taken for granted and it was well worth the time because the other adjacent Eastern Redcedar shrubs in my border screen do not exhibit any fungal rust symptoms. Scouting for disease is good gardening practice. You know what they say ‘an ounce of prevention is worth a pound of cure’. If you have Eastern Redcedar trees in your yard now is the time to inspect for any evidence of fungal rust disease. Your neighbor with a flowering crabapple may thank you.

Notes

[1] https://plants.ces.ncsu.edu/plants/juniperus-virginiana/

[2] https://hgic.clemson.edu/factsheet/juniper-diseases-insect-pests/

[3] https://content.ces.ncsu.edu/extension-gardener-handbook/5-diseases-and-disorders#section_heading_7616

[4] tps://ask2.extension.org/kb/faq.php?id=828832

[5] https://hgic.clemson.edu/factsheet/cedar-apple-rust/

[6] https://www.missouribotanicalgarden.org/gardens-gardening/your-garden/help-for-the-home-gardener/advice-tips-resources/insects-pests-and-problems/diseases/rusts/cedar-quince-rust

[7] https://extension.umn.edu/plant-diseases/cedar-apple-rust

[8] https://hyg.ipm.illinois.edu/pastpest/200715b.html

Resources and Additional Information

Read about another fungal disease that affects trees (Black Knot Disease: Apiosporina morbosa ) in a previous post by Melinda Heigel: https://durhammastergardeners.com/wp-admin/post.php?post=15569&action=edit

The links highlighted in the notes are excellent resources for learning more about fungal rust that can infect the Eastern Redcedar.

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Propagating Trees & Shrubs through Hardwood Cuttings

On By durhammastergardenersIn Durham NC, hardwood cuttings, how to propagate shrubs, how to propagate trees, propagation, Scion, Uncategorized, woody plants

By Peter Gilmer, NC State Extension Master GardenerSM volunteer of Durham County

(Image credit: University of New Hampshire Extension)

The “dead of winter” is an expression understandable when we had two weeks of cold and a touch of snow, not so understandable with temperatures in the 70s. For plants, the winter is a time of dormancy, both for deciduous as well as evergreen shrubs and trees. This time of year for gardeners often means planning, ordering seeds, and waiting for the soil to warm. It is also the right season for hardwood cuttings, a simple but often forgotten plant propagation technique.


Hardwood cuttings (also known as scions) are taken during the dormant stage of a woody plant, including both trees and shrubs, usually involving last year’s growth, and can be considered from the first hard freeze (late November for us?) through bud break in early spring. The technique is simple, fun, and often considered for a favorite plant or when seed propagation for a specific plant is difficult or slow.

(Left) A healthy donor plant, red twig dogwood (Cornus sericea), showing last year’s growth as the reddest of the stems, each about the diameter of a pencil. (Right) Five cuttings, ready to be dipped in planting hormone powder.  Each is cut horizontally just below a bud, and at an angle just above an upper bud. (Image credit: Peter Gilmer)

Where, When, and How to Take Cuttings

To be successful, the donor plant must be healthy. The cut is made just below a bud, often near the base of the plant and should be done with the health and final appearance of the donor plant in mind. The stem should be about the diameter of a pencil, and length does not matter initially as the stems taken will be cut again before sticking. The term sticking is used to describe the simple act of pushing the cut stem into the growing media. Plants with suckers and shoots are often good candidates, and juvenile stems do better than more mature ones.

Cuttings are best taken in the early morning on a cloudy day, to minimize sun exposure, and should be placed in an opaque plastic or paper bag, with a moist cloth or paper towel around the base. A cooler (without ice) may be helpful if many cuttings are being taken. Remember, cutting a stem is an injury to the donor plant, and should be done with a sharp tool cleaned with alcohol or a bleach solution to avoid disease transmission.

Once the long stem is taken from the donor plant, that stem is cut again with attention paid to the final stem length, bud locations, and polarity. In general, final cuttings should contain at least one bud that will be below ground, and at least one above ground. The bottom cut is generally made transversely just below a bud, and the upper cut made at an angle just above a bud. Polarity is easier to maintain if the angled cut is always up, and this also keeps moisture from potentially sitting in droplet form on the top of the stem. Stems will not root if planted inverted. The cuttings at this point are generally six to ten inches long, although this depends on the arrangement of the buds. Note that no terminal buds are kept in this technique, as the stems are usually too small in diameter near the top of the stem.

Rooting and Care of Hardwood Cuttings

Some cuttings can be stuck directly into the planting media, but most authors recommend dipping the base of the cut stem into rooting hormone prior to sticking. Rooting hormone can be purchased at most big box stores, usually in a powder form, and should be handled with gloves and eye protection, as the hormone can be caustic to eyes and to skin. Never dip the cutting into the original container to avoid contamination, and don’t use too much. More is not better, and in fact can inhibit root development. The planting media required is not unique or specific. Any commercially available planting soil or seed starting mix will work. It may be important to not have fertilizer already in the media, as new roots form more easily without initial fertilizer exposure. Most media options contain two or more of the following: perlite, pumice, peat, sand, and fine bark chips.

Taking care of the cuttings is relatively easy. The media should be kept moist, but not soggy. It is essential to avoid desiccation of the new cuttings, but cuttings are more commonly injured by being too wet (for example, in soil that does not drain well). The cuttings will need protection from direct sun, temperature extremes, and animal predation. For some this may be as easy as a container on the north side of the house, perhaps with chicken-wire on the top, with the option to move the container indoors during very cold nights.

Roots can take several months to form, so patience is required. The best way to assess root development is to tip over the container, gently dumping the contents. A cutting with generous fibrous root formation will maintain the entire planting media, while minimal or no root formation will allow the media to fall away. The cuttings can be fertilized once root formation is confirmed, and hardened off by gradually increasing sun exposure as leaves begin to form.

Have fun with this technique. It is fine to experiment. If you wonder “Can I take a cutting of this plant?”, give it a try. It is quite useful to research the potential donor plant using basic cell phone techniques. Simply ask Google “What is the best way to propagate “X” plant?”. We recommend searching for research-based information on sites with the domain .edu– such as https://plants.ces.ncsu.edu. For example, the best propagation technique for red twig dogwood is a hardwood cutting, while the best technique for white oak is an acorn. Enjoy this propagation technique in the dead of winter.

Resources and Additional Information

Hartmann and Kester’s Plant Propagation: Principles and Practices, 9th Edition. Pearson, 2018.

NC State Extension Gardener Handbook online chapter on propagation, 2018. https://content.ces.ncsu.edu/extension-gardener-handbook/13-propagation

Clemson Cooperative Extension Home & Garden Information Center online fact sheet.

Hardwood Cuttings for Shrub & Tree Propagation

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