Philadelphia just set a record that can't be broken. October 2024 was the driest month in Philadelphia recorded meteorological history - no measurable rain. None, zippo, zero, nada, nil. (The only way to beat such a record is if climate change goes turbo and results in negative rain. You know, when lots of drops come out of the ground and go straight up into the atmosphere. Just saying.)

It turns out that many of the cultivars they cite are among the so-called "ironclads" and/or have species native to Eastern North America in their parentage. Indeed, ironclads for the most part are hybrids of R. maximum, catawbiense or carolinianum. In a serendipitous bit of timing, the chapter's October, 2024, meeting featured Steven Kristoph, nurseryman and college instructor from central New Jersey, whose topic was ironclads. These hybrids were first described in the nineteen-teens, with lists from E. H. Wilson and Cornell's Ralph Curtis. The point was to identify rhododendrons that would survive the winters of the northeastern United States, given that so many cultivars from England died or were grimly set back when America's deep freeze winters locked in.

Here are some other takeaways from the Journal articles and Steve's presentation summarized by Michael Martin Mills:

• Older cultivars that have stood the test of time are likely to be better at standing the test of the future. Keep in mind that our summers can be like ovens now.

• A surprising number of almost-local hybrids make the drought tolerance cut - cultivars bred by Joseph Gable of York County, Pa.

• Yellows and oranges may be doomed. It took forever to breed some winter-hardy ones, and it turns out they are real wimps in hot dry spells.

• Truly appropriate planting conditions are more important than ever. Drainage, drainage, drainage plus lots of organic content. The way the weather is going, if you plant a rhododendron in a marginal site don't be surprised by marginal results. And if you don't mulch - not for weed prevention but to minimize drying of the soil - you're a nincompoop.

• Whoever heard of 'Lady Grey Egerton'? This lilac-tinged white is an English hybrid by Waterer, pre-1890, cited by C J Patterson in her Journal article as the "most drought-tolerant ironclad I know of." It may be an English cross, but the key parent is the American native R. catawbiense. Even Joe Gable extolled is performance in dry spells.

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References:

"This has been more than just a dry spell" by Michael Martin Mills in the DVRS Autumn 2024 Rhodogravure

Contributed by Michael Marin Mills, November 5, 2024

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Rhododendron 'Tony'



Photo by Harold Greer. Harold described 'Tony' ('Boule de Neige' x red catawbiense seedling) as a hardy Shammarello hybrid with glowing cherry red flowers. Somewhat crinkly foliage decorate this handsome low growing rhododendron. In ten years it grows to 4'. It is hardy to 15F.

The devastating winter of 1938 in South Euclid, Ohio, induced Tony Shammarello to begin hybridizing. Ninety percent of the rhododendrons in the Shammarello field were devastated. Tony thought that, while he was at it, he might as well aim at producing rhododendron hybrids heavily foliaged and of modest stature.

In 1943 Tony Shammarello crossed 'Boule de Niege' with a selected red catawbiense and after several years of selection introduced the plant in the illustration and named it 'Tony'. His primary objective was to obtain a dwarf red, which he certainly achieved. The bright cherry red trusses are at their best in late May and are bud hardy to -20 degrees F. The leaves are 4" long and 1¾" wide, thick dark green and slightly crinkled. The plant habit is extremely sturdy and compact. Sadly, Tony Shammarello passed away in 1982, but his many rhododendron hybrids including 'Tony' survive him.

Through the years, the rhododendron 'Tony' has been overlooked to a large extent. Recently, Mike Stewart sent rooted cutting to many nurseries in areas around the US to evaluate as commercial plants In field trials they ran. The one rhododendron that was most frequently admired was 'Tony,' the Shammarello hybrid.

R. 'Tony' has a good compact plant habit, lush dark green foliage, and tolerance to sun, shade, heat, and cold. Grows to a height of about 4 feet in 10 years, making it a relatively compact shrub with dense foliage suitable for the suburban landscape. The foliage provides year-round interest, even when the plant isn't in bloom. Tolerance of cold temperatures down to -15°F (-26°C), makes it suitable for many climates. It prefers partial shade but can tolerate more sun if it has adequate moisture. It can be planted as an accent in borders and foundation plantings and adds a focal point to any landscape. As a bonus, it attracts bees, making it a valuable addition to pollinator gardens.

Overall, Rhododendron 'Tony' is a fantastic choice for gardeners who want a vibrant and low-maintenance shrub that adds beauty to their landscape. Its striking red flowers and attractive foliage make it a standout plant that will surely be admired by all who see it.

Now, the efforts of Mike Stewart, Van Veen Nursery, and the American Rhododendron Society will make sure it is available to rhododendron nurseries around the US.

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References:

"Rhododendron Tony" by Alfred Martin in the QBARS: V25N2, 1971

"In Memoriam: Tony Shammarello" by David Leach in JARS: V37N1, 1983

Contributed by Steve Henning, October 26, 2024

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Fatal Tick-borne Disease: Babesiosis



The deer tick is the most common vector for babesiosis.

Recently, the horticulture community mourned the loss of Wayne Mezitt, a renowned horticulturist, who passed away due to complications from babesiosis. But what is babesiosis. Babesiosis is a tick-borne disease that has been gaining attention due to its increasing incidence and potential severity.

Transmission of Babesiosis

Babesiosis is primarily transmitted through the bite of an infected black-legged tick (Ixodes scapularis), commonly known as the deer tick. These ticks are most prevalent in the Northeastern and Upper Midwestern United States. The disease can also be transmitted through blood transfusions, organ transplants, and from mother to baby during pregnancy or delivery, although these modes of transmission are less common. The causative agent of babesiosis is a microscopic parasite called Babesia, which infects red blood cells. The most common species causing human babesiosis in the United States is Babesia microti.

Recognizing Babesiosis

The symptoms of babesiosis can vary widely, ranging from mild to severe. Some people may remain asymptomatic, especially if they are otherwise healthy. However, in others, particularly those with compromised immune systems, the elderly, or individuals with underlying health conditions, the symptoms can be severe and potentially life-threatening.

Common symptoms of babesiosis include: fever, chills, sweats, headache, body aches, loss of appetite, nausea, and fatigue.

In severe cases, babesiosis can cause hemolytic anemia (destruction of red blood cells), leading to jaundice and dark urine. Additionally, it can result in thrombocytopenia (low platelet count), leading to easy bruising and bleeding.

Complications of Babesiosis

Babesiosis can lead to several serious complications, particularly in high-risk individuals. These complications include: acute respiratory distress syndrome (ARDS), disseminated intravascular coagulation (DIC) which can lead to widespread clotting and bleeding, heart failure, kidney failure, and splenic rupture.

The severity of complications can be influenced by factors such as age, immune status, and the presence of other medical conditions.

The fatality rate of babesiosis is relatively low for the general population but can be significant in high-risk groups. The Centers for Disease Control and Prevention (CDC) reports that the overall case-fatality rate is approximately 5-10% among hospitalized patients. However, in immunocompromised individuals, the fatality rate can be higher.

According to the CDC, the number of reported cases of babesiosis has been on the rise. In 2019, there were over 2,400 reported cases in the United States. The actual number of cases is likely higher, as many cases may go unreported or misdiagnosed.

Prevention and Awareness

Preventing babesiosis primarily involves reducing the risk of tick bites. This can be achieved by:

• Avoiding areas with high tick populations, especially during peak tick season.
• Wearing long sleeves and pants when in wooded or grassy areas.
• Using insect repellents that contain DEET.
• Wear clothing treated with the insecticide permethrin.
• Performing thorough tick checks after spending time outdoors.
• Promptly removing any attached ticks.

Awareness and education about babesiosis are crucial for early diagnosis and treatment. If you develop symptoms of babesiosis after a tick bite or after spending time in areas where ticks are common, seek medical attention promptly.

Babesiosis, while relatively rare, can have serious consequences, particularly for vulnerable populations. Understanding how the disease is transmitted, recognizing its symptoms, being aware of potential complications, and knowing the severity can help in early detection and treatment. As we remember Wayne Mezitt and his contributions to horticulture, let us also take this opportunity to raise awareness about babesiosis and the importance of tick bite prevention.

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References:

CDC: Neurologic Complications of Babesiosis

NIH: National Library of Medicine: Babesiosis

NY State Dept. of Health: Babesiosis

Contributed by Steve Henning, July 29, 2024

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Wayne Mezitt: 1942-2024



Wayne Mezitt (center) accepts ARS Pioneer Achievement Award on behalf of his father, Edmund V. Mezitt at ARS 2022 Fall Meeting at Gettysburg, PA.

Wayne Mezitt of Hopkinton, MA, passed away on July 18, 2024. He was a revered figure in the horticulture industry and a dedicated champion of the genus Rhododendron. Wayne's contributions have left an indelible mark on our gardens, our hearts, and the very fabric of horticulture itself.

Wayne Mezitt's journey began in Hopkinton, Massachusetts, where he grew up surrounded by the beauty of nature and the nurturing environment of his family's business, Weston Nurseries. His passion for plants was evident from a young age, and it was clear that he would follow in the footsteps of his father and grandfather, both of whom were esteemed horticulturists.

Wayne's dedication to horticulture was not just a profession; it was a calling. He possessed a profound understanding of plants, coupled with an insatiable curiosity and a commitment to innovation. Under his stewardship, Weston Nurseries flourished, becoming a beacon of excellence in the industry. His leadership transformed the nursery into a thriving hub for gardeners, landscapers, and plant enthusiasts, offering a diverse range of high-quality plants and expert advice.

One of Wayne's most significant contributions was his work with Rhododendrons. He was passionate about this genus, captivated by their stunning blooms and diverse varieties. When Wayne's father, Edmund V. Mezitt was recognized with the ARS Pioneer Achievement Award, it was mentioned that from his father's hybridizing, Wayne had selected and registered 44 lepidote rhododendrons, 27 deciduous azaleas, 23 elepidote rhododendrons and 7 evergreen azaleas. These varieties brought adaptability, toughness, and beauty to places where rhododendrons were never expected to grow. They are still being sought by landscapers and the gardening public

Wayne's horticultural legacy spans over six decades. His meticulous breeding programs focused on enhancing the hardiness, disease resistance, and aesthetic appeal of these beloved plants, making them more accessible and enjoyable for gardeners everywhere. Wayne's impact extended beyond the boundaries of his nursery. His lectures and writings were a source of inspiration and education for many, and his contributions to horticultural journals and publications have left a lasting legacy of knowledge.

He was an active member of various horticultural societies, sharing his knowledge and expertise with fellow enthusiasts. Wayne was a past president of American Nursery and Landscape Association, The Massachusetts Nursery and Landscape Association, the Massachusetts Horticultural Society, the Massachusetts Invasive Plant Council, the Horticultural Club of Boston and the Massachusetts Agricultural Club. The ARS Massachusetts Chapter awarded Wayne the Bronze Medal in 1992.

In addition to his professional accomplishments, Wayne was a mentor, a teacher, and a friend to many. He believed in the power of community and the importance of nurturing the next generation of horticulturists. Through his mentorship programs and involvement in educational initiatives, he inspired countless individuals to pursue their passion for plants and horticulture.

Wayne Mezitt's legacy is one of beauty, innovation, and dedication. His work has brought joy to countless gardeners and nature lovers, and his contributions will continue to bloom in gardens for generations to come. As we remember Wayne, let us cherish the contributions he made to horticulture and the genus Rhododendron that have truly made the world a more beautiful place.

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References:

Weston Nursery Statement

Boston Globe's Wayne Mezitt Eulogy

JARS, Spring 2023

Contributed by Steve Henning, July 29, 2024

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OpenAI on Rhododendrons & Azaleas

I asked Open AI artificial intelligence about growing rhododendrons and azaleas in the Philadelphia region. The first answer included using Aluminum Sulfate which is toxic to rhododendrons and azaleas after repeated applications. When informed of that, it thanked me and revised its post. Here is what OpenAI came up with. It is good for the most part.

Climate Considerations

Hardiness Zone: The Philadelphia region falls in USDA Hardiness Zones 7a to 7b. Rhododendrons and azaleas generally thrive in these zones, but it's essential to choose varieties that are well-suited to this range.

Temperature Extremes: Be prepared for cold winters and hot, humid summers. Winter protection might be necessary for less hardy varieties.

Soil Requirements

Acidic Soil: Both rhododendrons and azaleas prefer acidic soil with a pH between 4.5 and 6.0. Philadelphia’s native soil can vary, so it’s crucial to test the soil pH and amend it if necessary. Elemental sulfur or iron sulfate can be used to lower the pH safely.

Well-Drained Soil: These plants do not tolerate waterlogged soil. Ensure the planting site has good drainage to prevent root rot. Raised beds or amended soil with organic matter like peat moss can help improve drainage.

Planting and Care

Location: Choose a location with dappled shade. While they need some sunlight for blooms, too much direct sun can cause leaf scorch, especially during the hottest parts of the day.

Mulching: Mulch around the plants to conserve moisture, regulate soil temperature, and prevent weeds. Use organic mulch like pine needles, wood chips, or bark.

Watering: Keep the soil consistently moist but not waterlogged. During dry spells, deep watering is necessary. Ensure that the water reaches the root zone.

Fertilization

Acidic Fertilizers: Use fertilizers formulated for acid-loving plants. Avoid high-nitrogen fertilizers that can promote leaf growth at the expense of flowers.

Timing: Fertilize in early spring before new growth begins and again after flowering. Avoid late-summer fertilization, which can promote new growth that might not harden off before winter.

Pests and Diseases

Common Pests: Be vigilant for pests such as lace bugs, which can damage foliage. Neem oil or insecticidal soap can help manage these pests.

Disease Prevention: Proper spacing and good air circulation can help prevent fungal diseases like powdery mildew and root rot. Avoid overhead watering to minimize fungal issues.

Winter Protection

Mulching and Burlap Wraps: Apply a thick layer of mulch in late fall to insulate the roots. For less hardy varieties, consider using burlap wraps to protect them from harsh winter winds and cold.

Pruning

Timing: Prune immediately after flowering to shape the plant and remove dead or diseased wood. This timing ensures that you don’t remove next year’s flower buds.

Technique: Light pruning is generally sufficient. Avoid heavy pruning, which can stress the plants and reduce blooming.

Specific Varieties

Local Recommendations: Consult local nurseries or extension services for recommended varieties that perform well in the Philadelphia region. Native or locally adapted species often have better resistance to local pests and diseases.

Gardeners in the Philadelphia region can successfully grow beautiful rhododendrons and azaleas, enhancing their landscapes with these vibrant, flowering shrubs.

References:

Contributed by Steve Henning, May 26, 2024

 

Sadly, 15 years ago Hank Schannen passed away on September 16, 2009, at the age of 71. He had joined the ARS Princeton Chapter 43 years earlier in 1966. Hank’s enthusiasm for rhododendrons combined with his gregarious personality led him to visit rhododendron hybridizers as far away as the West Coast and Germany. Hank became a popular speaker not only for his knowledge and photography, but also for his down-to-earth humor.

He would say, "My idea of an erotic dream is ‘Roseum Elegans’ in twenty-one different colors."

When speaking at the Pilchuck Chapter in Washington State, after Amby Schultz introduced him, Hank stated "You did that introduction so well, I would like you to do my epitaph." Amby shot back in an instant, "Lie down and I'll start writing." Hank smiled and replied, "I won't touch that. You're too quick for me."

Hank knew how to make a point. After he founded Rare Find Nursery in Jackson, NJ, he published a catalog featuring his many favorite rhododendrons and the other plants he loved. After his passing the Catalog featured his Criteria For Success with Rhododendrons, a list which those who knew him had heard in his programs.

References:

Contributed by Steve Henning, April 1, 2024

Currently there are 1,159 distinct Rhododendron species officially recognized. But, who decides which plants are the members of genus Rhododendron? It turns out that taxonomists and botanists publish their research and propose changes in classifications, hence names. Then an official body, the International Botanical Congresses, a collaboration between The Royal Botanic Gardens, Kew; The Harvard University Herbaria; and The Australian National Herbarium, meets every five years to update the official list. That is the International Plant Names Index (IPNI).

Some changes added new members to genus Rhododendron:

Common Name Sand Myrtle Western Labrador Tea Marsh labrador tea Labrador Tea Wild Rosemary Mock Azalea Minniebush

Present Name Kalmia buxifolia Rhododendron columbianum Rhododendron tomentosum Rhododendron diversipilosum Rhododendron groenlandicum Rhododendron hypoleucum Rhododendron tolmachevii Rhododendron tomentosum Rhododendron tomentosum Rhododendron subulatum Rhododendron benhallii Rhododendron menziesii Rhododendron goyozanense Rhododendron katsumatae Rhododendron multiflorum Rhododendron pentandrum Rhododendron pilosum Rhododendron kroniae Rhododendron yakushimense

Former Name Ledum buxifolium Ledum columbianum Ledum decumbens Ledum diversipilosum Ledum groenlandicum Ledum hypoleucum Ledum macrophyllum Ledum maximum Ledum palustre Ledum subulatum Menziesia ciliicalyx Menziesia ferruginea Menziesia goyozanensis Menziesia katsumatae Menziesia multiflora Menziesia pentandra Menziesia pilosa Menziesia purpurea Menziesia yakushimensis

Newest members of genus Rhododendron in Pennsylvania.

Above: Rhododendron pilosa
Right: R. groenlandicum

According to the USDA Plant List, these are the rhododendron species native to Pennsylvania, New Jersey, Delaware, or Maryland:

Common Name Smooth Azalea Coastal Azalea Flame Azalea Rhodora Labrador Tea Great Laurel Pinxterbloom Azalea Minniebush Roseshell Azalea Swamp Azalea

Present Name Rhododendron arborescens Rhododendron atlanticum Rhododendron calendulaceum Rhododendron canadense Rhododendron groenlandicum Rhododendron maximum Rhododendron periclymenoides Rhododendron pilosum Rhododendron prinophyllum Rhododendron viscosum

Former Name Ledum groenlandicum Rhododendron nudiflorum Menziesia pilosa Rhododendron canescens

References:

The International Plant Names Index (IPNI): https://www.ipni.org/
The World Flora Online: http://www.worldfloraonline.org/
New Plant List: https://www.kew.org/read-and-watch/new-plant-list-released
USDA Plant List: https://plants.usda.gov/

Researched by Steve Henning, August 12, 2023