April 2002

Tilt Ramblings:

April could become Peony month in the South. We are going back to China this month to look for heat tolerant peonies for Alabama and the South. There is a good collection of Peonies at the Wuhan Botanical Institute which offers a similar or even hotter climate than Mobile. We always want what we do not have or can not grow! Before going, I thought I would search the world over for peony expertise and found a distributor and garden in Lawrenceville, GA. Shen Huang is the owner of the gardens and has been evaluating a large number of cultivars for about 8 years. It was obvious which ones were doing well and which ones would prefer to be in New York or in other northern habitats. Shen gave me a list of the ones he felt performed well close to Atlanta. I have included his web site and address if you would like to try some in your area. We will start with what he has learned and compare the ones we bring back from China. Check back next month to see some of the treasures we found.


DISCLAIMER: Please remember that all information presented is a summary of research and not an endorsement of any product or a recommendation of chemicals. The official labels from the manufacturing companies offer the legal and proper use and handling information for all products.

The following articles are featured in this month's Something to Grow On:











Shen Huang, President of Golden Port International in Lawrenceville, Georgia, tells us that the following tree peonies are doing well in Atlanta:


  • Jade Flower (Ru Hua Si Yu)
  • Pink Water-lily (Rou Fu Rong)
  • Hundred Smiles (Bai Hua Cong Xiao)
  • Baiyuan's Pink (Baiyuan Fen)
  • Blue Lotus (Lan Furong)
  • Phoenix White (Feng Dan Bai)
  • Jade Plate White (Yu Ban Bai)
  • Rainbow Glow (Ni Hong Huan Cai)
  • Caozhou Red (Cao Zhou Hong)
  • Beautiful Spring Red (Chun Hong Jiao Yan)
  • White Jade Tower (Yu Lou)
  • Bright Red (Hu Hong)
  • Vigorous Red (Chang Hong)
  • Red Bridal Veil (Qing Luo)

According to Mr. Huang Japanese tree peonies have a very good chance to grow in Atlanta. They are all late varieties which will not be damaged by late frost.

Mr. Huang reports that most of the Chinese herbaceous peonies are doing well in Lawrenceville.

Our thanks to Mr. Huang for permitting us to use the following photographs:

Jade Flower

Pink Water-lily

Baiyuan's Pink

Blue Lotus

Phoenix White

Jade Plate White

Rainbow Glow

Caozhou Red

Beautiful Spring Red

Bright Red

Vigorous Red

Red Bridal Veil

If you have questions you can reach Mr. Huang at:

Golden Port International
2255 Cedars Road
Lawrenceville, GA 30043

Call Toll Free 1-877-PEONIES


The horticulture industry considers environmental regulations its biggest governmental issue, according to the latest NMPRO online poll. 38% of 198 respondents named it the top issue, over immigration reform (33%), estate tax repeal (13%), hort research funding (11%) and new ergonomics rules (5%). The current online poll deals with pricing trends. To participate, go to

(from Todd Davis at the NMPRO email of April 2, 2002)


The American Horticultural Society announced details about the updated USDA Hardiness Zone Map it plans to release this fall. The new version will have 15 zones, including 4 new zones for semi-tropical and tropical regions. It will be available on the Internet and published on a CD-ROM. The map will be based on 1986-2002 weather information. The previous version was based on 1974-1986 data. AHS received a USDA grant to update the map.
(from Todd Davis at the NMPRO email of April 2, 2002)


Botrytis is a plant disease capable of doing significant damage to crops in the greenhouse. Infection develops in 60-70 degree temperatures. High humidity, poor air circulation, temperature fluctuations, and slow plant growth encourage the growth of botrytis.

Sixty thousand spores can be produced from a dime sized diseased spot. The airborne spores can infect an entire greenhouse. The disease eventually progresses from watery spots on soft leaf and petal tissue to a brown unsightly mold.

To prevent an outbreak it is important to purchase disease-free plant materials. In the greenhouse, moisture management is critical. Plants need good plant spacing and air circulation. Water the substrate, not the leaves. Practice good hygiene by removing dead leaves and blooms.

Decree is a fungicide that can be used to prevent an outbreak. The re-entry interval is four hours. It can be applied to open blooms and as a pre-ship treatment. For more information contact SePRO Corporation at 317-580-8297 or visit http://www.sepro.com


There are a number of diseases that attack the roots of bedding plants. The prevention of many of these diseases has to do with water management. The longer the growing medium remains wet, the more likely is the development of root diseases. It's important to irrigate early in the day so the medium has a chance to dry. When you water plants air is forced out of the medium. If oxygen isn't reintroduced quickly carbon dioxide levels are increased and that stymies root growth and activity. When roots aren't growing properly pathogens have time and space to grow.

Sanitation is very important. Water, tools, hands, hoze nozzles, and shoes can move a pathogen from one root to another. Sweeping improperly can move infected soil from one place to another with diastrous results. It is smart to not reuse medium and even flats, unless you can be sure that you have removed all pathogens in the cleaning process.

To aid in the prevention you can encorporate biological control products into the medium (RootShield, SoilGard, Mycostop and others).

The following are common diseases found in bedding plants:

DAMPING OFF: rotting of seed or seedlings caused by Pythium, Phytophthora or Rhozoctonia. This occurs when the growing medium has been contaminated and plants are overwatered. Misting overhead exacerbates the problem. Diseased plants must be eliminated quickly.

PHYTHIUM ROOT ROT: All bedding plants are susceptible. Root tips are infected first, then the roots and then the lower leaves often yellow and wilt. Ideal conditions for phythium are high soluble salt concentration in the growing medium, overwatering and excessive overhead misting during propagation. You can manage phythium with good sanitation. Fungicides used for this problem are: etridiazole, fosetyl-Al, mefenoxam and propamocarb.

PHYTOPHTHORA ROOT ROT AND AERIAL BLIGHT: Infected plants die within one to two weeks after developing symptoms. Extended periods of hot, wet weather, frequent overhead irrigation and heavy fertilization increase disease development. Manage with sanitation and the monthly application of azoxystrobin or fosetyl-Al.

RHIZOCTONIA ROOT ROT AND WEB BLIGHT: Begonia, impatiens and petunias are very vulnerable. Plants wilt, fall over and break off at the soil line. Careful attention to sanitation will help prevent the spread. Fungicides that help: fludioxonil, iprodione, PCNB, thiophanate methyl, triflumizole.

BLACK ROOT ROT: Caused by the fungus Thielaviopsis basicola. Leaves turn yellow, plants wilt and then die. Roots become black and water soaked. Surfaces in the greenhouse become contaminated with this fungus. Strict stanitary measures will help.

(from "Reduce Root-rot Disease Losses" by Jean L. Williams-Woodward, published in GMPRO February 2002)


Thrips are a perpetual problem in greenhouse settings. They are commonly found on fuchsia, impatiens, gerbera, tuberous begonia, Russian sage, petunia, ascelpias, aster, marigold, mixed baskets and planters and vegetable transplants. Prevention is the most effective tool. At Bailey Nurseries in Minnesota, before the annual growing season begins, all plant debris and growing media are removed. GreenShield, a disinfectant, is applied to all interior surfaces. Greenhouses are tightly closed for two weeks and 70 degree temperature is maintained. At the end of the two weeks, a total-release aerosol insecticide is applied to eliminate remaining insects.

A 30' radius around the greenhouse is treated with pre-emergent herbicides to keep weeds away. All incoming plant materials are inspected. It is very important to scout your plants to keep track of how many pests you have. Yellow sticky cards placed vertically inside pots will allow you to count thrips. Carefully monitoring thrips will help you determine how many thrips your plants can tolerate. Five or fewer thrips can be controlled with environmentally friendly pesticides like BotaniGard, Azatin or Conserve. More thrips than that will require stronger pesticides like carbamate or organophosphates (DuraGuard, Closure, Mesurol or Orthene - used to rescue crops when the thrips population explodes or for spot treatments).

(from "Living with Thrips" by Jean-Marc Versolato, published in GMPRO February 2002). If you would like a copy of the entire article send your request to Bernice Fischman: bfischma@acesag.auburn.edu


The control of spider mites in the greenhouse is a doable task but it requires a great deal of planning and attention to detail. There are a number of products, old and new, that are specifically registered for use on greenhouse and nursery ornamentals. You must use the correct product for the particular site. There are products that cover the upper and underside of the leaves. Some products affect eggs and the very young larvae while others will deal with a full blown adult infestation. Products will last from 14 to 28 days. There is also a very large range of REI (restricted entry interval) times that might impact on whether or not you use a specific product. Small print on the labels will give rather specific details about how frequently they can be used and under what conditions.

When using products from the table below be sure to:

  1. Frequently inspect plants. Sticky tape traps probably will not work.
  2. Make sure you spray the underside of leaves.
  3. Avoid using water with a pH above 7.0.
  4. Spray when temperatures are between 65 and 85 degrees F.
  5. Do not water from overhead for abour 4 hours after an application.
  6. Clean and rinse spray tank and hoses before every application.

    Trade NameCommon nameCompanyChemical Class*REI (Hrs)Mites Controlled**
    AvidabamectinSyngentaglycoside12SM, BRM, CYM, ERM, RM
    FloramitebifenazateUniroyalcarbazate4SM, ERM, CRM, SRM
    HexygonhexythiazoxGowanthiazolidinone12SM, ERM, CRM, SRM
    KelthanedicofolDow Agroorganochlorine12SM, BRM, CYM, RM
    OvationclofentezineScottstetrazine12SM, ERM
    PylonchlorfenapyrOlympicpyrrole12SM, BRM, CYM, RM
    SanmitepyridabenScottspyridazinone12SM, BRM,SRM, TUM
    Triact 70neem oilOlympicoil4"mites"
    Ultra-fine Oilparaffinic oilWhitmireoil4SM
    Vendexfenbutatin-oxideGriffin L.L.Corganotin48SM

    *Products in different chemical classes may have the same (or similar) mode of action (e.g., Akari and Sanmite, Pylon and Vendex). Products with the same mode of action should not be applied in consecutive applications.
    **BRM = broad mite; CRM = citrus red mite; CYM = cyclamen mite; ERM = European red mite; RM = rust mite; SRM = southern red mite; SSM = spruce spider mite; SM = spider mites; TUM = tumid mites.

    (From "Managing Spider Mites: The New and the Old" by Richard K. Lindquist, published in GPN, October 2001).



    Jackie Mullen
    Extension Plant Pathology Specialist

    February was unusually warm and many saucer magnolia and even some azaleas in the Auburn area had blossoms developing and opening during the second and third week of the month. The unusually warm weather in February resulted in a larger number of plant samples for diagnosis than usual. Most of the 36 samples received were from landscape situations. The freezing night temperatures of the past two weeks have definitely slowed down spring-like landscape developments. Cold damage on many landscape plantings will be evident as tip scorching of new growth. Also, we expect branch and trunk cracking from cold injury to start to show up in April-June. Dieback will result from these injuries.

    In February we started to see some anthracnose (Colletotrichum) leaf spots on azalea, Asiatic Jasmine and liriope, due to the warm weather. Spotting was usually seen as small brown, round spots. Fungal spores were not present; fungus identification was made on the basis of fungal growth with spore production in cultures.

    Pestalotia leaf spots were present on gardenia as gray, blotchy, irregular spots. These spots often develop on landscape shrubs early in the spring when leaves are stressed and sometimes injured by cold.

    Pythium root rot was identified on azalea, gardenia, holly, and Asiatic jasmine. Pythium as a disease agent of woody ornamentals is questionable. Pythium is known to cause root decay of feeder roots of woody ornamentals (often young plants) when the plants are weakened and wet soil conditions have been present for a period of time. In a landscape, disease control (or management) typically involves removal of the dying plant and improvement in soil drainage in the area. Some soil replacement may be helpful as Pythium spores may remain active in the area for a few years, depending upon environmental conditions. Pythium is not considered to be the serious problem to woody ornamentals that the Phytophthora fungus is. Pythium is a serious problem on herbaceous plants in the landscape or greenhouse. Protective fungicide drenches are recommended to help control Pythium (or Phytophthora) in greenhouse and nursery situations. Also, water problems must be corrected.

    Brown patch was active on St. Augustine and centipede grass samples from the Mobile area. When weather warms up, three-four applications of a protective fungicide (See Alabama Pest Management Handbook) will be needed to control this problem.

    Also, one sample of St. Augustine grass from Mobile was received with active growth of the take-all patch fungus. This is normally a warm-weather disease problem, but warm weather had been present for much of February. See ANR-823. Try to avoid stress conditions as much as possible.

    February 2002 Plant Diseases Seen In The Plant Diagnostic Lab at Auburn

    Azalea Colletotrichum Leaf SpotCullman, Talladega
    AzakeaPythium Root RotPike
    CentipedeBrown Patch (Rhizoctonia)Mobile
    GardeniaPestalotia Leaf SpotTalladega
    GardeniaPythium Root RotCoffee
    HollyPythium Root RotMadison
    Jasmine, AsiaticColletotrichum Leaf SpotHouston
    JasminePythium Root RotHouston
    LiriopeAnthracnose (Colletotrichum)Cullman
    Pear, BradfordBotryosphaeria CankerCoosa
    PlumBlack Knot (Plowrightia)Pike
    St. AugustineBrown Patch (Rhizoctonia)Mobile
    St. AugustineTake-All Patch (Gaeumannomyces graminis pv. graminis)Mobile

    *Counties are not reported for greenhouse and nursery samples.

    J. Jacobi
    Extension Plant Pathology Specialist

    The lab received 33 samples for the month of February. Some of the problems seen last month included Phytophthora root rot on azalea and shore juniper, eriophyid or rust mites of white pine, and black knot on plum (Prunus domestica).

    Black knot, caused by the fungal pathogen Dibotryon morbosum (also called Plowrightia morbosum), is a common disease of plum and cherry trees (Prunus species). The fungus attacks twigs and branches forming black, hard, knots or gall-like swellings. This disease is common on wild black cherry (Prunus serotinia) in forests and other natural areas. The knots on the branches slow the flow of water and nutrients causing stunting and dieback of branches. The disease becomes progressively worse during each growing season and if left uncontrolled, the tree can weaken and die. Control of black knot can be achieved by a combination of cultural and chemical control measures. First, prune out knots at least six inches below signs of disease in late winter before outbreak. Second, when establishing new plantings, choose resistant varieties. Japanese varieties of plums are generally less susceptible than most American varieties. Third, the application of fungicides can protect new twig growth from disease, but should be used in conjunction with cultural practices. For the most current fungicide recommendations and spray schedules, refer to extension publication ANR-1055, Black Knot on Plum and Cherry Trees (www.aces.edu/dept/extcomm/publications/anr/anr-1055/anr-1055.htm). Follow all of the manufacture’s label directions and precautions when using any pesticide.

    2002 January Diseases Seen In The Birmingham Plant Diagnostic Lab

    AZALEAPhytophthora Root RotJefferson
    BOXWOODLeaf MinerJefferson (2)
    BOXWOODVolutella BlightJefferson
    CAMELLIATea ScaleJefferson
    CLEYERWax ScaleJefferson
    IVY, ENGLISHAnthracnose (Colletotrichum sp.)Jefferson
    JUNIPER, Shore ‘Blue Pacific’Phytophthora Root RotJefferson
    PANSYPythium Root & Crown RotJefferson
    PINE, 'White ‘Pendula’Eriophyid Mites, White Pine AphidsJefferson
    PLUMBlack Knot (Dibotryon morbosum)Jefferson
    ROSEWinter InjuryJefferson
    ZOYSIAGRASSWhite Grubs (Phyllophaga sp.)Jefferson

    Disease Possibilities for March Diseases often reported in early spring include Helminthosporium leaf spots on bermuda and small grains; the beginnings of powdery mildews, rusts, and/or Septoria leaf blotch on small grains; some downy mildews; Botrytis blight; and bacterial leaf spots on greenhouse crops.

    Go to: Disease Reports see a list of some common disease problems received in the lab during March and early April of the past few years. Comments on control practices are brief. Refer to the fact sheets, timely informations, 2000 or 2001 spray guides, and the Alabama Pest Management Handbook for details.


    April to October, 2002:
    Floriade 2002.
    See the AmeriGarden (5,400 square feet), part of the world horticulture exhibition in the Netherlands.
    For more information call 808-961-6660 or visit
    http://www.floriade.nl/ or http://www.amerigarden2002.com/

    May 31 - June 1, 2002:
    A Center for Applied Nursery Research Topical Meeting
    Hydrangeas - Beginning to End
    Augusta Technical College and the Center for Applied Nursery Research
    Thomson and Dearing, GA
    Call 706-597-8309; Internet: www.canr.org

    July 12 - 15, 2002:
    ANLA Convention & Executive Learning Retreat.
    San Diego, CA. Contact ANLA at 202-789-2900; Fax, 202-789-1893

    August 1-4, 2002:
    SNA 2002 - Southern Nursery Association Researcher’s Conference and Trade Show
    Georgia World Congress Center, Atlanta, GA.
    Contact SNA at 770-953-3311; Fax 770-953-4411; SNA Infoline, 770-953-4636; e mail: mail@mail.sna.org
    URL: http://www.sna.org

    August 11-17, 2002:
    American Society for Horticultural Science and XXVI International Horticultural Congress & Exhibition.
    Metro Toronto Convention Centre, Toronto, Ontario, Canada.
    Contact ASHS at 703-836-4606, Fax: 703-836-2024, E-mail: ashs@ashs.org
    URL: http://www.ashs.org

    September 26, 2002:
    Fletcher Field Day.
    Ornamentals field day at the Mountain Horticultural Crops Research Station in Fletcher, North Carolina.
    Contact Dick Bir (rbir@fletcher.ces.state.nc.us) for more information.

    September 29-October 2, 2002:
    Eastern Region International Plant Propagators' Society NA and IPPS Southern Region NA Annual Meeting.
    Hunt Valley (Baltimore), MD.
    Contact Margot Bridgen at 26 Woodland Road, Storrs, CT 06268; 860-429-6818, E-mail: mbippser@neca.com or Dr. David L. Morgan, 332 Warbler Drive, Bedford, TX 76021; ph. 817-577-9272; e-mail, dleemorgan@msn.com

    October 4-5, 2002:
    Middle Tennessee Nursery Association Horticultural Trade Show.
    McMinnville Civic Center, McMinnville, TN
    phone: 931-668-7322; fax: 931-668-9601; e-mail: mtna@blomand.net,
    http://www.mtna.com/ or http://www.southeasternnursery.com/mtna/

    January 15-17, 2003:
    Mid-AM Trade Show.
    Navy Pier, Chicago, IL. Contact: Rand Baldwin at 847-526-2010, Fax 847-526-3993, e-mail mail@midam.org
    URL: http://www.midam.org

    January 30 - February 02, 2003:
    ANLA Management Clinic.
    Louisville, KY.
    Contact ANLA at 202-789-2900; Fax, 202-789-1893
    URL: http://www.anla.org

    February 23-26, 2002:
    Plasticulture 2002.
    30th American Agricultural Plastics Congress
    Contact ASP at 717-238-9762, Fax 717-239-9985, e-mail pheuser@calabreseheuser.org
    URL: http://www.plasticulture.org

    July 15 - 20, 2003:
    ANLA Convention & Executive Learning Retreat.
    Location TBA. Contact: ANLA, 202-789-2900; Fax, 202-789-1893.
    URL: http://www.anla.org

    July 30-August 2, 2003:
    SNA 2003- Southern Nursery Association Researcher’s Conference and Trade Show.
    Georgia World Congress Center, Atlanta, GA.
    Contact SNA at 770-953-3311; Fax 770-953-4411; SNA Infoline, 770-953-4636.

    September 30 - October 4, 2003:
    American Society for Horticultural Science Annual Meeting and 100th Anniversary.
    Providence, RI.
    Contact ASHS at 703-836-4606, Fax: 703-836-2024, E-mail: ashs@ashs.org
    URL: http://www.ashs.org

    October 3-4, 2003:
    Middle Tennessee Nursery Association Horticultural Trade Show.
    McMinnville Civic Center, McMinnville, TN
    phone: 931-668-7322; fax: 931-668-9601; e-mail: mtna@blomand.net,
    http://www.mtna.com/ or http://www.southeasternnursery.com/mtna/

    October 5-8, 2003:
    IPPS Southern Region NA.
    San Antonio, TX.
    Contact: Dr. David L. Morgan, 332 Warbler Drive, Bedford, TX 76021; phone 817-577-9272; e-mail, dleemorgan@msn.com

    July 29 - 31, 2004:
    SNA 2004 - Southern Nursery Association Researcher’s Conference and Trade Show.
    Georgia World Congress Center, Atlanta, GA.
    Contact: SNA 770-953-3311; Fax 770-953-4411; SNA Infoline, 770-953-4636
    URL: http://www.sna.org

    October 1-2, 2004:
    Middle Tennessee Nursery Association Horticultural Trade Show.
    McMinnville Civic Center, McMinnville, TN
    phone: 931-668-7322; fax: 931-668-9601; e-mail: mtna@blomand.net,
    http://www.mtna.com/ or http://www.southeasternnursery.com/mtna/

    October 3-6, 2004:
    IPPS Southern Region NA
    Greenville/Spartanburg, S.C.
    Contact: Dr. David L. Morgan, 332 Warbler Drive, Bedford, TX 76021; phone 817-577-9272; e-mail, dleemorgan@msn.com

    Send horticultural questions and comments to ktilt@acesag.auburn.edu.

    Send questions and comments to bfischma@acesag.auburn.edu.

    Letters to Bernice Fischman - 101 Funchess Hall - Auburn University, AL 36849.