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Potomac Valley Chapter ARS

Potomac Valley Chapter
of the
American Rhododendron Society
Newsletter: Fall 2002

"Plant Hunting along the Salween River in Yunnan Province"
by Steve Hootman

Annual Fall Banquet: October 20, 2002 4:00 - 8:00 PM - Registration Deadline 10/10/02

Registration deadline for our fall banquet at JR's Stockyards Inn is almost here. If you haven't sent in your check for $30 per plate and selected either the Prime Rib or Grilled Salmon, do so as soon as possible. Mail your check to treasurer Phyllis Rittman by October 10th. We have lined up a number of exceptional auction plants including great deciduous azaleas, dwarf evergreen azaleas, rhododendron species and hybrids, and a few companion plants too.

Our speaker will be Steve Hootman, the Co-Director of the Rhododendron Species Foundation. He will be giving us a most outstanding program that you won't want to miss. Over a five-year period, Steve took three expeditions to China where his focus was the extreme northwest corner of the Yunnan Province in China. The area is bordered to the west by "Myanmar" or Burma along the "Gaoligong Shan" range, to the north by "Xizang" or Tibet, and to the east by the "Nu Jiang" or the Salween River. The entire region has been relatively untouched by plant explorers due to its very remote location. However, it is known to be an exceptionally rich and diverse area for rhododendron species and many other choice plants.

With the cooperation of the Kunming Institute of Botany, Steve and several other experts in the rhododendron world including Peter Cox and Dr. David Chamberlain traversed the rugged terrain in that region seeking rare rhododendron species growing in their natural habitats. They explored the Salween / Irrawaddy Divide and reached the Hpimaw Pass on their second trip and by the third trip made it to the dramatic Dulong River gorge formed by a tributary of the Irrawaddy. Most of the plants they found are ones that very few of us have seen although some names may be familiar to hybridizers. Brief descriptions of some of the unusual rhododendron species Steve encountered are offered later in this newsletter for your reference. Anyway, you won't want to miss Steve's entertaining tales of plant exploration or his beautiful slides of rhododendrons and awesome scenery in this remote region.

Some Rhododendron Species Seen by Steve Hootman in Northwestern Yunnan

The following species are ones that Steve Hootman identified as plants he and the other scientists identified while hiking in Yunnan. References used to describe these rhododendrons came from two books by Peter A. Cox, The Larger Species of Rhododendrons and Dwarf Rhododendrons.

A widely distributed species that can grow up to 100 feet tall in the Himalayas (right). Leaves are 7 inches long by 2 1/2 inches wide, dark green and glossy above with tan or gray plastered indumentum below. Flowers are blood red and 2 inches across in compact trusses of 20 blossoms in the forms that grow at lower elevations but often deep rose to pink or even white at higher elevations.

arboreum ssp. delavayi var. peramoenum
A sub-species form that is smaller and less tree like, only about 30 feet tall. Leaves are more narrow, 6 inches long by 1.5 inches wide with wooly indumentum underneath. The 2-inch flowers are bright cherry-scarlet to deep rose crimson in trusses of 15 to 20.

A large shrub or small tree up to 30 feet high. Leaves can be large, up to 6 1/2 inches wide and 13 inches long, and heavily indumented underneath in a deep cinnamon to fawn color. Flowers are white to cream or pale yellow, about 1 1/2 inches, and veined with pink or purple.

An erect to spreading shrub to about 4 feet. The oblong to elliptic leaves are usually evergreen but can be semi-deciduous, about 1.5 to 2 inches long, and highly aromatic. Flowers are small, about 3/4 inches long, greenish to pale yellow and hang in pendulous clusters of three.

Typically an upright shrub that can reach as high as 15 feet tall. The shiny, lance shaped leaves are about 4 inches long by 2 inches wide, dark green above and densely scaly below. The tubular flowers are 1 1/2 to 2 inches long, and come in shades of yellow-orange, apricot, red, salmon, to plum purple, often multi-colored. The pendulous blooms hang in clusters of 2 to 9.

cinnabarinum ssp. tamarense
A sub-species form of cinnabarinum with tubular flowers of deep royal purple to pale lavender.

cinnabarinum ssp. xanthocodon
A sub-species form where the flowers are not quite so tubular since the floral tube opens much wider than the typical form. Those in the Concatenans group have flowers of a striking orange shade whereas forms in the Pallidum and Purpurellum groups range from pink to reddish purple

A 10 to 20 foot shrub in the Argyrophyllum sub-series. Leaves are about 4 inches long and 1 inch wide, dark green and leathery above with a thin buff to ash-gray indumentum below. Flowers are funnel-campanulate, about 1 inch, and appear in loose trusses of 20 to 30 blossoms.

Low growing species, 8 inches to sometimes 3 feet tall. Leaves are elliptic to oblong, 2 to 3 inches long and 1 inch wide. Flowers are bright canary yellow, bell shaped, and up to 1 1/2 inches wide.

An open shrub to as high as 15 feet with leaves 4 inches long and 1 1/2 inches wide. The funnel shaped flowers are 3 to 4 inches, white tinged with pink and flushed with yellow at the base.

dichroanthum ssp. scyphocalyx
A small shrub about 4 to 5 feet tall with lance shaped leave 4 inches long by 1 inch wide and thin fawn to gray indumentum. The 1 1/2 inch tubular flowers in loose trusses of 4 to 8 have a waxy substance and can be shades of bronze, apricot, yellow or orange, possibly flushed with crimson.

A small shrub from 3 to 10 feet tall with dark green, deeply grooved leaves measuring 4 inches long by 1 1/2 inches wide with brown indumentum. The 4-inch flowers are white tinged with pink and very fragrant.

A small shrub up to 4 feet tall with leaves 2 inches wide by 1 inch long. The funnel shaped flowers are pale yellow and 2 inches across, coming in compact trusses of 2 to 5 blossoms.

A tall, narrow shrub from 4 to as high as 15 feet tall with red to mahogany peeling bark. Leaves are 4 inches long by 1 inch wide. The small flowers are about 2/3 inches long and appear on long pedicels in groups of 4 to 15. The color is plum to deep port-wine with a grayish-blue sheen.

A shrub to 40 feet high in the Thomsonii sub-series with leaves 5 inches long by 2 inches wide. The 1 1/2 inch flowers are pink to deep rose and are held in moderately compact trusses of 10 to 12 blossoms.

An open shrub or small tree, 15 to 25 feet high. Oblong leaves are 1 to 4 inches wide and can be anywhere from 4 to 12 inches long, bright green above but with reddish-brown indumentum below. The 2-inch flowers are rose-scarlet to crimson and come in trusses of 10 to 20 blossoms.

A shrub or small tree to 15 feet tall. Leaves are 2 to 3 inches wide and 4 to 9 inches long, dark green and rough above but with dense cinnamon-brown indumentum below. Flowers are 2 inches long, scarlet to deep crimson and appear in fairly compact trusses of 15 blossoms.

An erect shrub to 7 feet with small oblong leaves 3/4 inch wide by 2 inches long. The funnel shaped flowers are about 1 to 1 1/2 inches long, pale pink to deep rose but occasionally white, and have deep crimson spots. They appear in groups of 1 to 3 blooms.

A small plant from 1 to at most 4 feet tall with elliptical leaves 1 inch long by 1/2 inch wide. Flowers are about 3/4 inches wide in lemon to sulphur-yellow and appear singly.

An erect shrub that can reach 10 feet tall with leaves 5 inches long by 2 inches wide, dark waxy green with thick brown indumentum. The 2-inch flowers are deep crimson, 10 to 20 per truss.

A large shrub or tree that can reach as high as 100 feet tall in the wild. Leaves are proportionately large measuring 10 inches wide by 22 inches long, matt green on the surface and often indumented below. The 3-inch flowers are in trusses of 20 to 30 and can be pale pink to rose or mauve.

A shrub form 2 to 7 feet tall with small leaves measuring 2 inches long by 1 inch wide. The 2 to 3 inch flowers are typically held singly and are white to pink.

sanguineum ssp didymum
A small shrub occasionally reaching as high as 6 feet. The oval leaves are about 2 inches long and 1 inch wide, dark green above with a gray to pale fawn colored indumentum underneath. Flowers are dark, black-crimson about 1 1/2 inches across in a loose trusses of 3 to 6.

A small, slow growing plant reaching 1 to possibly 3 feet in height. Leaves are about 2 1/2 inches long by 1 inch wide, dark green and puckered above with a dense brown indumentum underneath. The sulphur-yellow flowers are open and cup shaped, about 1 1/2 inches across.

A sparsely branched shrub to about 10 feet but with dark, reddish-brown and gray peeling bark Leaves are 5 inches long by 2 1/2 inches wide and sometimes recurved. The extremely fragrant flowers are tubular-funnel shaped and about 4 inches long in pure white with a yellow throat.

A small shrub from 2 to 5 feet tall with lance shaped leaves of shiny dark green about 2 to 5 inches long by 1 inch wide. The tubular flowers are usually pale pink to rose, about 1 inch long and about as wide, and appear in trusses of 3 to 9 blossoms.

A shrub that can vary from 2 feet to 35 feet tall. Lance shaped leaves are 2 to 3 inches long by 1 inch wide, dark green above and scaly below. Flowers vary in color from white, pale lilac, purple, rose, pink, to almost salmon and measure about 1 1/2 inches. Trusses carry 3 to 5 blossoms.

Planning Ahead: District IX Meeting - "Rhododendron Legacies"

Dates: Thursday, April 24 - Sunday, April 27, 2003

Location: Country Inns & Suites, Annapolis, Maryland (800)-456-4000 or (410) 571-6700
      Standard Rooms with 2 Queen Beds at $80 or King Suites (can sleep 3) at $99
      Mention the American Rhododendron Society to get our conference rate.
      Registration Materials will be sent out in February with deadline March 24th, 2003

  • Thursday - April 24, 2003
    Afternoon tour of historic Annapolis followed by harbor boat ride. Dinner on your own at one of many excellent restaurants on the wharf. Short opening program back at the hotel that evening.
  • Friday - April 25, 2003
    Bus tour past DC sights including Capitol building and selected monuments. Visit the Botanical Gardens and then enjoy a guided tour of the National Arboretum. Dinner back in Annapolis at local restaurants. Evening program at the hotel. Flower Show and Plant Sale open.
  • Saturday - April 26, 2003
    Visit local gardens including Carol Segree and Bob McWhorter and then Londontown. Evening banquet, auction, and speaker Scott Vergara, formerly of the Rhododendron Species Foundation
  • Sunday - April 27, 2003
    Visit local gardens on your own before heading home.
Plant Sale: Hard-to-find Gable, Delp, Haag, Kehr, and Ring hybrids. Many other goodies including rare evergreen azaleas, native azaleas, rhododendrons, companion plants, and some new deciduous azalea introductions from Clarence Towe, Tom Dodd, and others.

Planning Meeting - Pot Luck: Sunday, October 27, 2002

Margaret White has graciously allowed us to hold another meeting at her lovely home on Sunday afternoon, October 27th, from 1:00 to 5:00 PM. We will be trying to organize committees and plan details for next spring?s District Meeting in Annapolis. We cannot handle this operation alone, so we need the help of many chapter members to serve on the following committees:

  • Registration and Publicity:
    Assemble registration and attendee packets. Send out meeting announcements in early February. Collect forms and record events. Help man registration desk.
  • Hospitality:
    Help people locate various activities within the hotel. Assist people getting on tour buses, and finding local restaurants. Help with box lunches and refreshments at the local gardens.
  • Plant Sale:
    Help set up and man the plant sale. Make sure plants are labeled with prices and are properly arranged. Assist treasurer with money collection and crowd control during sales events.
  • Tours:
    Serve as Bus Captains during tours. Help driver with directions and keep people on time.
  • Other:
    Coordinate minor program details and speakers. Assist MAC Chapter with Flower Show

Although this was scheduled as "Board Meeting", we want to invite anyone who is interested in helping us during our upcoming District Meeting. Committee chairs are already assigned but we desperately need about 10 to 15 extra people to help us stage the event. Since good food and good fellowship go hand in hand, we thought we would make this a "pot luck" similar to our picnic. If you forget to bring something to eat, don't worry because there are always plenty of extra snacks. This should be an enjoyable afternoon so please join us. We need your help!

"Friends" of the White Garden: The Beginnings of an ARS Display Garden

As surely you know by now, Margaret White has given her lovely 13-acre estate (shown to the left) to Fairfax County for a Horticultural Park. To help Margaret maintain the property and to begin a chapter effort to establish an official ARS Display Garden there, we have organized an informal "Friends" group that meets at her home the 1st and 3rd Wednesdays of each month, weather permitting. We arrive sometime after rush hour, around 9:00 to 9:30 (or whenever), and stay for as long as people desire. Currently we are doing garden chores like pruning, raking leaves, weeding, transplanting, labeling, etc. If you can spare a few hours, stop by and stay as long as you want. Bring a bag lunch if you desire.
Next scheduled "Friends" dates: October 16, November 6, and November 20, 2002.

Dr Max Byrkit Awarded the Bronze Medal

At our chapter meeting on September 15, 2002, the Potomac Valley Chapter of the American Rhododendron Society awarded its highest honor, the Bronze Medal, to Dr. Max Byrkit. Max was a chapter President during the early years of our organization and he has generously supported our activities over many years. Thank you Max! We appreciate all you have done.

"Ask the Experts"
Notes from Our September Meeting - by Amy McDaniel, Secretary

Potomac Valley Chapter members had the opportunity to ask a panel of experts questions on a variety of horticultural topics at our September 15th meeting. The panel was composed of ARS President H. Edward "Ed" Reiley, District IX Alternate Director Don Voss, past chapter President Bruno Kaelin, and recent Bronze Medal recipient Max Byrkit. The question-and-answer session has been paraphrased and then grouped into categories below.

Stressors of Rhododendrons and Azaleas: Drought, Disease, and Pests

** Gray Carter brought a rhododendron from his slat house, one of three that has brown tips.
Q. Have these plants been overwatered or underwatered?
A1. Brown tips indicate underwatering. The tender growth has dried out but the plant will recover. [Reiley]

** Gray Carter brought an azalea (Beethoven) whose leaves are cupping.
Q. Is there something wrong with this plant?
A1. It shouldn't cup. [Kaelin]
A2. There could be root damage due to water deficit. Also, fresh pine bark can cause problems. Six weeks of composting pine bark with nitrogen would make it suitable for use. [Reiley]

** Jon Wallenmeyer asked about the cause of dieback.
Q. Why does dieback occur?
A1. Stress invites disease. [Reiley] (referring to the drought)
A2. Our heat also encourages Phytophthera (a Genus of fungi) in plants from the West Coast. [Byrkit]
A3. Once a plant has Phytophthera, the fungus can only be suppressed with a chemical such as Subdue, not killed. [Reiley]
A4. Dieback gets into tips and goes down the stem. [Reiley] (referring to another fungus, Botryosphaeria)
A5. Drying stress is always bad, even if plants recover at night. You need to water all summer. In Atlanta, Dr. Joe Coleman grows rhododendrons despite the perception that the climate prevents them from thriving there. He waters A LOT. Also, there must be good drainage. [Kaelin]
A6. A gardener who unknowingly crossed melons with gourds, which looked good even though they were not good to eat, was asked about how she watered them. She used milk containers filled with water and with holes drilled in the bottom to slowly drip moisture to the plants. [Byrkit]
A7. Different plants have different resistance to different stresses. [Reiley]
A8. "Very Berry" has done well. [Byrkit] (referring to a hybrid rhododendron?s resistance to drought)
A9. "Mist Maiden" is very stress-resistant. Nothing seems to bother it. [Reiley]

** Jon Wallenmeyer asked about watering this time of year.
Q. Should plants be watered in the fall?
A1. Root systems need water now to encourage the growth of small roots before winter. [Reiley]
A2. Even evergreens shouldn't go into winter dry. [Kaelin]

** Gray Carter has a "Ginny Gee" rhododendron which has been watered well but looks dried up and dead.
Q. What might cause this plant to wilt?
A1. There is probably root damage, possibly caused by Phytophthera. [Reiley]

** Bob McWhorter asked about petal blight.
Q. What can be done to prevent petal blight?
A1. I started spraying this year. [Byrkit]
A2. You can't fix it without spraying with Bayleton or Strike. There's a new chemical out, too. [Reiley]

** Don Hyatt mentioned the outbreak of Sudden Oak Death on the West Coast.
Q. Do we need to be concerned about Sudden Oak Death here on the East Coast?
A1. The problem here is drought stress. [Reiley]

** Gray Carter asked about the cause of Sudden Oak Death.
Q. Is Sudden Oak Death due to Phytophthera?
A1.Yes. And Sudden Oak Death does get into rhododendrons. It is not known if this hurts them, although rhododendron nurseries on the West Coast were closed for awhile in order to prevent the spread of this disease through transport of nursery stock. Sudden Oak Death is killing lots of trees, not just oaks. [Reiley]
Note: Phytophthera ramorum is the full name of the pathogen responsible for Sudden Oak Death.

** Carol Segree mentioned stem borers.
Q. What can be done about stem borers?
A1. Marathon or Merit brand granules work best in the spring when they wash into the soil and then go up the roots of the plant. This method also protects the plant against lace wings. However, at this time of year (fall), stem borers can only be removed by hand. [Reiley]

** Jane Goodrich asked about the efficacy of coffee grounds.
Q. Will coffee grounds repel weevils?
A1. Such a treatment might repel weevils, but it won't kill them. [Reiley]

** Harry Dewey also mentioned weevils/borers.
Q. Will Cygon kill weevils/borers?
A1. I'm not sure. [Reiley]
A2. I don't think so since they are inside the plant at this time of year. Orthene, Lindane, and Dursban are all effective to kill weevils during the months of June and July. [Kaelin]

** Jon Wallenmeyer brought in a plant where the leaf surface had been severely eaten causing the foliage to become brown and shriveled. He had pictures of the long, light brown, and elusive bugs he suspected as the culprit of the damage. (shown to the right)
Q. What can be done to protect plants against bush crickets without applying artificial chemicals?
A1. Neem is effective and is an organic plant-derived pesticide. Pyrethrin would be ineffective against these insects. Bush crickets are a recent problem in this area. [Reiley]

** Bob McWhorter asked about bud damage.
Q. What could be eating the buds?
A1. Caterpillars such as the fall army worm will eat buds. Neem is repellent to amost any insect. [Reiley]

** Amy McDaniel asked about insecticidal soaps.
Q. What kinds of pests are insecticidal soaps effective against?
A1. Insecticidal soaps smother soft-bodied insects, but the chemical must get onto the bug in order to be effective. [Reiley]

Q. Beer did not work against slugs. What works?
A1. I use Ortho. [Byrkit]
A2. You might try a copper barrier. Strip an electrical wire and place it around the plant. [Reiley]

Q. Beavers?
A1. I saw seventy trees taken down in one area by beavers, but did not take action until they hit the crape myrtle. [Byrkit]

Q. Deer?
A1. Fences and dogs will deter them. They do not like to eat Yaks ("Yakushimanum"). [Byrkit]

Q. Rabbits?
A1. Rabbits love "Gumpo" and "Satsuki" azaleas. They are tough to deter, although cats might help. [Byrkit]

Q. Squirrels?
A1. I tried using mothballs to deter squirrels and they just buried them. [Byrkit]

Environmental Concerns of Rhododendrons and Azaleas: Fertilizer, Mulch, and Sunlight

** Val Lorenz asked about a cutting she rooted a year ago.
Q. I have a year old rooted cutting with no new growth. What would help?
A1. It might need to be outside during the cold season. Fertilize it after the frost, nitrogen for the roots, and maybe next spring it will grow. I use no chemicals on deciduous cuttings. Use a tender growth cutting so that it will root quickly and then fertilize it early (after it has rooted). It will grow the following spring. Pinch the tip on the cutting before removing it from the plant to encourage growth. Apply one third to one half strength fertilizer as soon as the cuttings root. [Reiley]
A2. Deciduous cuttings must be taken from early/soft growth and they must show new growth during that first year or they will eventually die. I grow them under sixteen-hour lights. [Kaelin]
A3. Low light combined with too much fertilizer is deadly. Only use VERY dilute solution on cuttings. [Hyatt]
A4. You must remove the blooms from cuttings. [Byrkit]
A5. Those blooms do take energy away from the rooting process. [Reiley]

** Don Hyatt asked about fertilizing azaleas in the fall.
Q. Since azaleas are more sensitive to fertilizer, might they have more problems when fertilized in the fall?
A1. Applying fertilizer in the fall as plants go dormant is tougher in this area because the weather does not make a gradual temperature decline as winter approaches. You must watch the progression of temperatures. An even descent to cooler weather is an ideal condition under which to fertilize, but mostly it doesn't work out that way. [Voss]
A2. I like to use Osmocote. [Byrkit] (Osmocote is a time-release fertilizer.)
A3. Fall fertilizing is not needed for large plants, more for nursery stock and small stuff. Definitely you should wait for dormancy. [Reiley]
A4. During the month of March on a radio broadcast of years ago, I heard some advice on fertilizing azaleas from Jack Eden. It was amusing because the amounts he suggested would outright kill the plants! [Voss]
A5. Do go light on the fertilizer. Good mulch helps. [Reiley]
A6. Avoid hardwood mulch. It forms a crust and introduces mineral problems in the form of the trace metal molybdenum. [Voss]
A7. Pine bark lasts twice as long anyway. [Reiley]
A8. Do not use "tan bark". It encourages disease. [Byrkit]
Note: The panel agreed that pine needles were the best mulch.

** Bob McWhorter asked about the tolerance of rhododendrons to sunlight.
Q. Do the sunlight needs differ for different rhododendrons?
A1. Plant the rhododendron in question in progressively more light until damage shows. The most sunlight it will take is the best condition. [Reiley]
A2. "Scintillation" will disintegrate in full sun. [Kaelin]
A3. A lady named Snowdrop Koontz grew "Glendale" azaleas in Hagerstown in both full sun and clay soil. It worked against all expectations. [Byrkit]

Other comments and questions about rhododendrons and azaleas

** Dr. Byrkit related his experience with black walnut trees.
My nemesis has been black walnuts. They will kill azaleas and rhododendrons. I planted them where a black walnut tree had been gone a year or two, but my plants died more quickly the closer they approached the original location of the tree. Squirrels had likely planted seeds from the tree in that area. After that experience I removed the stump of the tree and put in test plants before risking good ones.

** Gray Carter brought two plants of "Bellrose", one whose leaves were wrinkled.
Q. I have some "Bellrose" that were potted at the same time as this one (the one with wrinkled leaves) and others have leaves that are unwrinkled. Does this one have a problem?
A1. I think it is a mislabeled plant whose wrinkled leaves are normal. [Reiley]
A2. It might be a maximum Leachii. [Byrkit]
A3. "Bellrose" is a R. smirnowii hybrid and normally has those twisted, wrinkled leaves. The plant with the dark green flat foliage is probably the one mislabeled. The wrinkled one looks just like my "Bellrose". [Hyatt]

** Val Lorenz asked about the crossing of rhododendrons with azaleas.
Q. What about Azaleadrons?
A1. "Prior's Red" worked, but very few of these crosses take. [Reiley]
A2. "No Suchianum" is a cross between rhododendron and mountain laurel, hard to make and odds are against its success. [Byrkit]

A New Chapter Website: www.donaldhyatt.com/ARSPVC

Don Hyatt has been working on a chapter website with online color newsletters. If you are reading this, you have found the website and the Fall 2002 Newsletter.

Reminder: Don't forget to pay your dues!

Copyright © Donald W. Hyatt 2002