April 2001

April: Hopefully the trucks are still rolling and nursery and landscape activities are at a fever pitch.

It is April in Auburn and all the Spring driving azalea trails are being heavily traveled when it is not raining. It is amazing that after a year of a devastating drought, where you are saying I will never complain about rain again, that you find yourself wishing for a sunny day. There is never a "normal" year. This is a typical, normal abnormal spring. However, when the clouds break, it is a beautiful spring and should be a great time for retail garden centers to fill everyone's gardens with azaleas. After all, Alabama is the Azalea Capital of the World.

This leads into an experiment that was installed last year by Dr. Gary Keever and Dr. Charles Gilliam to evaluate azaleas in central Alabama. We have gotten great information from our crapemyrtle, shade tree, Indian Hawthorn, groundcover rose, crabapple and other plant trials. It is about time that we searched the nurseries and back yard azalea breeders for a representative sample of available azalea cultivars and see which ones offer the best heat, cold, pest, and environmental tolerances for Alabama. It is also important to evaluate growth rate, aesthetic appeal (do the dead flowers cling to the plant?), flowering time and make that information available to nurseries and landscape design professionals as well as home gardeners so they can make informed selections in what to grow and use in the landscape. This is done routinely in vegetable and row crops as well and animal breeding. It is just as important economically to find plants that thrive in our environment in Alabama. Grounds maintenance is the fastest growing segment of horticulture and this information means savings of millions of dollars in spraying and maintenance problems to this industry.

The study has been installed at the Camp Hill experiment station. The first year has already given us great data on winter damage from some extreme temperatures we experienced this winter. We will report that information as soon as it is available. Since it is sometimes difficult for people to get to Camp Hill, we are working on getting a single plant of each of the 167 cultivars to plant at Auburn in the teaching gardens. Of course we will post pictures and information on this web site as well. We are thankful to van der Giessen Nurseries for their contributions of liner sources for the project. John Olive, Superintendent of the Ornamental Horticulture Substation in Mobile, and the great crew at the station propagated and grew one gallon containers for transplanting. Another 150 to 200 cultivars are being readied for next fall's planting. Wanda and Charles Hanners of Azalea Trace Nursery in Huntington, MD have collected and mailed a major portion of the cuttings we now have in the test. In these times of proration, we are going to have to have an even greater partnership with industry in order to function effectively in our research, teaching and extension programs.

I would offer an update on the extent of the damage caused by proration but we are still in the dark until the legislature makes some decisions. We do need your support to lessen the impact and for the recovery process. Please take every opportunity you can to support Extension, Higher Education and K-12. All are important to our state and our industry.

The big news this month is the launching of our new Plant Identification Site. This has been almost a 2 year project to launch the beginnings of a plant database for use by our Nursery Certification Program, Urban Foresters, Landscape Professionals, Master Gardeners, Horticulture classes, and anyone in the world who wants information on plants used in Alabama and the Southeast. Bernice Fischman, our horticulture extension web master, has offered her expertise and artistic talents to develop this great resource. We thank the Alabama Cooperative Extension Service and Urban and Community Forestry grant monies for supporting this project. If you are receiving this newsletter as an email, take time to visit the site at www.ag.auburn.edu/landscape . Now that we have the structure for the site, we will be adding new plants each month. The great thing about a web site is that it is dynamic and the amount of information you can post is unlimited. Please let us know if you see any problems and as always we welcome your suggestions.

A final note on a plant I saw this month that is not used very often. The picture below shows a Pink Titi plant (Cliftonia monophylla).

This is an evergreen shrub that grows to about 10 feet and has great lustrous green leaves. The flowers, pink in this case, are very attractive. I think you will agree that if people got the word and saw this plant, they would be anxious to empty their savings to have one in their yard. Stick cuttings and spread the word! Have a nice April!

Ken


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

PLANT IDENTIFICATION RESOURCE LAUNCHED ON INTERNET

WATER RESTRICTIONS TIGHTENED

THE WALNUT TREE

FUEL INCREASES NOT EASILY ABSORBED IN TEXAS

CONTROLLING ENERGY COSTS IN THE GREENHOUSE

NORTHWEST REGION HONORED

WATERING BY THE CLOCK

SOIL SAMPLE DATA SHEETS ONLINE IN N.C.

PLANT PATHOLOGY REPORT

UPCOMING EVENTS


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.


PLANT IDENTIFICATION RESOURCE LAUNCHED ON INTERNET

You can find it on our home page http://www.ag.auburn.edu/landscape or just click on the graphic below.

To use the database type in a common name and hit enter. You will be given, in many instances, a choice of plants. Click on the name to take you to the plant of choice. If you don't know the common name click on SEARCH and it will take you to an alphabetical list of all of the scientific names of plants in our database. Just click on the plant that you would like to see.


WATER RESTRICTIONS TIGHTENED

Florida’s drought conditions prompted Water Management Districts (WMD) to impose water restrictions for nurseries and landscape contractors. Criteria are subject to change, so growers are told to check with your local district and be aware that local utility companies’ rules can supercede water districts’ decisions. N.W. Florida and Suwannee River WMDs have not issued mandatory restrictions. Parts of St. Johns River WMD have both voluntary reductions and specific restrictions that differ from county to county. S.W. Florida WMD has several emergency restrictions. S. Florida WMD also has several restrictions that differ from county to county. (http://www.fnga.org)

(from NMPRO email 3/20/2001)
Ken Tilt notes: Every year the water restrictions get a little worse. ARE WE PREPARED?

THE WALNUT TREE

(The following information is taken from the
January/February 2001 VNA Newsletter).

BLACK WALNUT AND ALLELOPATHY
Though grown primarily for its wood and nuts, black walnuts are often found growing on landscape sites where they serve primarily as shade trees. When certain other landscape plants are planted near or under this shade tree they tend to yellow, wilt and die. This decline occurs because the walnut tree produces a non-toxic, colorless chemical called hydrojuglone. Hydrojuglone is found in leaves, stems, fruit hulls, inner bark and roots. When exposed to air or soil compounds, hydrojuglone is oxidized into the allelochemical juglone, which is highly toxic.

Several related trees such as English walnut, hickories and pecan also produce juglone, but in smaller amounts compared to black walnut. Juglone is one of many plant-produced chemicals that can harm other plants in a process known as allelopathy. (Additional common landscape trees with allelopathic properties: sugar maple, tree-of-heaven, hackberries, southern waxmyrtle, American sycamore, cottonwood, black cherry, red oak, black locust, sassafras, and American elm.)

JUGLONE IN THE SOIL
Juglone is exuded from all parts of the walnut tree. Juglone can affect other plants either through root contact, leakage or decay in the soil, falling and decaying leaves, or when rain leaches and drips juglone from leaves and branches onto plants below. Plants located beneath the canopy of walnut trees are most at risk because juglone from the roots and fallen leaves accumulates there.

Although juglone has low water solubility and does not move far in the soil, small amounts may be injurious to sensitive plants. Plant roots can encounter juglone when they grow within 0.5 - 0.25 inches from a walnut root. Walnut roots can extend in the soil well beyond the crown or drip line of the tree, affecting susceptible plants far from the black walnut.

The accumulation and depletion of toxins in the soil is affected by factors such as soil type, drainage, aeration, temperature and microbial action. Soil microorganisms ingest allelochemicals as energy sources, and metabolic decomposition can render the chemicals non-toxic to plants. When soils are well drained and aerated, a healthy population of aerobic microorganisms can accelerate this progress.

Wet, poorly aerated soil, very common in many urban areas, discourages microbial growth. Plants sensitive to the walnut tree's toxic effect may be at a higher risk when planted in heavy urban soils that lack organic matter. Toxins adhere to organic matter rather than being absorbed by plants, and organic matter also encourages a healthy soil microbial population.

Mycorrhizal fungi are commonly associated with forest tree roots and are considered necessary for normal uptake functions. Allelochemicals can disrupt the uptake process by damaging the root hairs or by inhibiting mycorrhizal populations in the soil. These different soil factors all have an effect on the accumulation or depletion of juglone produced by the black walnut tree.

REDUCING ALLELOPATHIC EFFECTS

TOLERANT GRASSES
Tall fescue and Kentucky bluegrass grow well near black walnut except during drought conditions when soil moisture is low. When moisture is adequate these grasses may grow better under walnut trees than in other parts of the lawn, possibly because the soil may be more basic. Soil under black walnuts tends to be alkaline, with the pH often 0.7 points higher than beyond the roots, thus influencing the growth of many different plants.

TOLERANT TREES AND SHRUBS
TOLERANT VINES, GROUND COVERS AND FLOWERS
PLANTS DAMAGED BY JUGLONE
REFERENCES
Brooks, M. G. 1951. Effect of black walnut trees and their products on other vegetation. Bulletin 347, West Virginia University, Agricultural Experiment Station, Morgantown, WV.

Coder, K. D., 1999. Allelopathy in trees. Arborist News 8(3):53-60.

Rietveld, W. J. 1983. Allelopathic effects of juglone on germination and growth of several herbaceous and woody species. J. of Chemical Ecology 9(2):295-308.


FUEL INCREASES NOT EASILY ABSORBED IN TEXAS

Texas Nursery and Landscape Association reports that simply absorbing high fuel prices from this winter has not been an option for most growers. In response to the increased production and shipping costs, growers are adding fuel surcharges to their products, raising prices outright or negotiating fuel bill payments. Some growers expect fuel prices to remain volatile for at least the next 2-3 years. 512-280-5182.

(from Todd Davis of NMPRO email, dated 3/27/01).


CONTROLLING ENERGY COSTS IN THE GREENHOUSE

With the ever increasing cost of energy it is critical to the operation of a greenhouse to properly maintain structures as well as make structural modifications that will enhance the product and minimize your expenses. During the Arab oil embargo of 1973 many conservation practices were put in place which, fortunately, became standard practices.

Fuel costs can be compared by using the following table. Determine how much you are spending on fuel. If it is more than the figures to the right, you are probably spending too much. Assume that the fuels were used in particularly efficient systems.

COMPARABLE FUEL PRICES
Typical FuelsEquivalent Cost
Fuel oil No. 2$1.00/gal.
Natural gas$7.50/1,000 cu. ft.
Propane$0.65/gal.
Coal (soft)$130/ton
Electric resistance$0.035/kwh

Structural modifications can produce great savings but you must be very selective. These changes typically are used to reduce air infiltration or to add extra insulation. Method and projected annual savings are in the table below. The energy savings are in comparison to a single-pane glass house. Poorly sealed houses will benefit significantly by these improvements.

MODIFICATION METHODANNUAL
SAVINGS
Major glasshouse modifications
Double-polyethylene filmover glass40%-60%
Glass lap and ounting sealants5%-40%
Single-layer polyethylene film over glass5%-40%
Double-layer polyethylene film30%-40%
Acrylic or polycarbonate twin-wall panels40%-50%
Curtains (night use)20%-50%
Polystyrene pellets (night and cold days)50%-80%
Other insulation modifications
Sidewall insulation up to bench height5%-10%
Foundation insulation3%-6%
Insulating ventilation fans boxes1%-5%
General maintenance
Structure3%-10%
Heating system10%-30%
Potential annual energy savings of greenhouse modifications compared to a single-pane glass house.

Obviously the potential savings relates to the condition of the greenhouse. If it is not sealed well then structural improvements will make a big difference. If the greenhouse is relatively sound the differences will not be that substantial.

The design of a heating system is very important for greenhouses. You want to deliver the correctly heated or cooled air to the plants and not elsewhere. Heat that escapes through a chimney or above the plants is a financial loss.

If the greenhouse operation is 1 or more acres, a high investment central heating system is most economical. For a smaller operation, unit space heaters are common and useful but because they are placed in the greenhouse air the parts don't last as long as a central system. Also, a great deal of warm air can be lost.

Management practices can save money. For example, decreasing night temperatures can reduce the annual fuel bill by as much as 3% for each 1 degree decrease. Computer control of temperatures is often very helpful.

Probably the most important factor in protecting your investment in a greenhouse is the adherence to proper maintenance procedures. Maintenance procedures may provide fewer savings than major modification but they are easier to do and will prolong the life of your structures and equipment. Proper maintenance will insure your business against failure during critical crop periods.


NORTHWEST REGION HONORED

U.S. EPA Northwest Region honored Monrovia Growers’ Dayton, Ore., facility for its environmentally friendly practices. The agency’s Evergreen Award recognizes the company’s irrigation runoff recycling, production of compost from green waste, reduced pesticide use, reduced hazardous waste production and recycling of plastic and paper products. The Northwest Region includes OR, WA, ID and AK. (503) 868-7941.

(from Todd Davis of NMPRO email, dated 3/27/01).


WATERING BY THE CLOCK

Attention growers in Florida’s St. Johns River Water Management District: the WMD changed a few restrictions. Nurseries with overhead irrigation can water inside from 8 a.m.-8 p.m. and outside from 4 a.m.-7 a.m. and 7 p.m.-11 p.m. 7 days/week . Flood irrigation of container plants using closed recovery/reuse systems can use the same schedule. Irrigation to allow heat stress is allowed from noon-5 p.m. every day, not to exceed 60 minutes per day per zone. Container plants may be watered 1 time any time of the day just before shipment. FNGA’s Ben Bolusky said the changes give growers some relief and flexibility. http://www.fnga.org

(from Todd Davis of NMPRO email, dated 3/27/01).


SOIL SAMPLE DATA SHEETS ONLINE IN N.C.

N.C. Dept. of Ag. developed a system for growers to fill out soil sample data sheets online. Online versions should be printed and sent with soil samples. The lab will match the printed and electronic version, reducing the amount of time needed to process paperwork. Results will now also be available online, so growers won’t have to wait for them to arrive by mail. http://www.ncagr.com/agronomi

(from Todd Davis of NMPRO email, dated 3/27/01).


EXTENSION PLANT PATHOLOGY REPORT

FEBRUARY PLANT DISEASES FROM THE
AUBURN AND BIRMINGHAM PLANT DIAGNOSTIC LABS

DISEASE POSSIBILITIES FOR MARCH

Jackie Mullen
Extension Plant Pathology Specialist

Jim Jacobi
Extension Plant Pathology Specialist

Auburn Plant Disease Report-February (J. Mullen)

February was unusually warm, especially the latter half of the month, and many landscape trees and shrubs have begun to develop new spring growth. In Auburn, Bradford pears are in full bloom. Cherries and saucer magnolias are also coming into full bloom as of the first days of March. Many of our 36 February plant samples were landscape dieback abiotic problems suspected to be related to the drought of last summer-fall.

In late February, we observed several leaf spot diseases on landscape plantings. Anthracnose and suspect Cercospora leaf spots were present. Cercospora does not grow out readily in culture isolations so Cercospora identification may be difficult unless we can find microscopic evidence of the fungus on plants.

Camellia samples were observed with three different leaf spots. Algal (Cephaleuros) leaf spot was identified by its characteristic green-red spots with greenish wavy, slightly raised edges. Warm, wet conditions favor algal leaf spot. In some situations copper fungicides may be applied as protective treatments. Colletotrichum leaf spot was diagnosed on the basis of culture results. Spots were circular and brown with a faint zonate pattern. Ulocladium was observed sporulating on large white leaf spots. This is a new finding on camellia. Pathogenicity testing would be needed before we can be sure Ulocladium is actually causing a leaf spot disease.

A New Guinea Impatiens sample showed large black leaf blotches and dieback of new growth. We expected to have positive results with our impatiens necrotic spot virus (INSV) ELISA testing, but we were surprised to find the INSV test was negative and the tomato spotted wilt virus (TSWV) testing was positive. These 2 viruses are closely related, and TSWV has been previously reported to occur on a few ornamentals along with the other common vegetable and peanut hosts. Sanitation and thrips control are the control recommendations for these 2 viruses.

Seiridium canker was observed on Leyland cypress as very large, elongated, dark, sunken lesions with abundant sap oozing down the infected tree trunk. Seiridium spores and spore-producing bodies were observed on the infected tree. Severely cankered trees must be removed. Small cankers could be pruned out. Cleary's 3336 may be applied as a protective spray treatment after pruning operations are completed. See the AL Pest Management Handbook.

John Olive at the Ornamental Horticulture Substation in Mobile reported seeing foliar nematode damage on Buddleia. The damage begins as chlorotic, angular spots which gradually become dark brown. John has seen this problem on verbena and lantana also. And, it has been reported to occur on Hosta.

2001 February Diseases Seen In The Auburn Plant Diagnostic Lab.
PLANTDISEASECOUNTY
CamelliaAlgal Leaf SpotLee
CamelliaColletotrichum Leaf SpotAutauga
CamelliaUlocladium Leaf Spot
(Possibly secondary)
Autauga, Lee
Cherry LaurelFungal Leaf Spot
(Previouslyundescribed)
Calhoun
English IvyAnthracnose (Colletotrichum)Lee
HollySuspect Cercospora Leaf SpotGeneva
Impatiens, New GuineaTomato Spotted Wilt VirusCalhoun
Leyland CypressSeiridium CankerRussell

Birmingham Plant Disease Report-February (J. Jacobi)

February was milder and slightly drier than average for the month. Most of the rainfall occurred in the last half of the month. The wet, mild conditions were favorable for disease on cool season turf and some ornamentals. Overall, 25 samples were submitted in January. We continued to receive samples of plants injured by the cold temperatures around the first of the year. Two samples of Yaupon holly (cvs. Nana and Bordeaux) were received from nurseries. These container-grown plants started to show symptoms and drop leaves as temperatures warmed up in late January and early February. Damage to the roots and crowns of these plants prevented normal water uptake resulting in death of foliage and branches.

We continue to see a large portion of the samples with diseases related to stress from our recent summer droughts. Botryosphaeria dieback of Rhododendron is commonly seen in landscape plantings following hot, dry summers. This disease rarely occurs in container-grown plants in nurseries. Characteristic symptoms include dying branches or stem dieback on an otherwise healthy plant. Leaves on diseased branches become dull green and then turn brown. The dead leaves remain attached to the stem. Examination of the wood of affected branches reveals reddish brown discoloration of the stem tissue. When viewed in cross section, the discolored wood often forms a wedge-shaped area pointing towards the center of the stem. Botryosphaeria dieback is difficult to control. With stress related diseases, proper site selection and watering during dry periods are the keys disease prevention. Once the disease is found, promptly prune out and discard dead and dying branches several inches below discolored wood. Spraying with a fungicide immediately after pruning may aid in control. Macrophoma leaf spot was seen on two samples. This disease is almost exclusively a problem on stressed, low vigor plants. So again, following good maintenance practices can reduce the risk of this disease without the need for fungicides.

2001 February Diseases Seen In The Birmingham Plant Diagnostic Lab
PLANTDISEASECOUNTY
AzaleaCercospora Leaf SpotShelby
ArborvitaeCold Damage/Pestalopsis Tip BlightJefferson
BoxwoodMacrophoma BlightJefferson (2)
BoxwoodPhytophthora Root RotJefferson
BentgrassBrown PatchJefferson
Carolina Cherry LaurelCherry Leaf Spot
Blumeriella jaapii)
Jefferson
Holly, Dwarf YauponCold Damage* (2)
RhododendronBotryosphaeria DiebackJefferson
*Counties are not reported for greenhouse and nursery samples.

Disease Possibilities for March

Cold weather in December after a warm fall that continued into November probably resulted in cold damage on many plants. Woody ornamentals especially may have been damaged. We are starting to see woody landscape plantings with the elongate bark cracks and resulting dieback typical of cold damage. Also, cold temperatures in early March following after two very warm weeks in late February will further increase cold injury to landscape ornamentals.

In addition drought last summer-fall will result in dieback this spring of several shrubs and trees. Shrubs and trees stressed from root injury will also be more susceptible to a variety of leaf spots and canker diseases.

Other diseases often reported in early spring include some downy mildews; Botrytis blight; and bacterial leaf spots on greenhouse crops.

The list below includes 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. The Alabama Pest Management Handbook can be accessed on line at the following URL: http://www.aces.edu/department/extcomm/publications/anr/anr-500/vol-1/2001PMHB.html

Disease Descriptions and Brief Control Comments
on Some Common Diseases Seen in March.
.
PLANT DISEASE DESCRIPTION CONTROL
APPLE, PEAR Fireblight (Erwinia) Flowers, pedicels, and leaves become black or dark brown and limp; canker development. Sanitation, See AL Pest Management Handbook, see ANR-542.
AZALEA Botryosphaeria Canker Sunken cracked lesions on branches. Often this canker follows cold injury or some other type of wound. Stressed plants are often involved. Sanitation.
AZALEA Botrytis Petal Blight Large irregular areas of blossoms turn brown; brown areas are covered with a gray delicate webbing during humid weather. See AL Pest Management Handbook.
AZALEA Cercospora Leaf Spot Roughly circular-angular brown-black spots (about 0.5 cm diam.); spots are usually associated with stressed plants. Sanitation of fallen leaves. Maintain proper fertility and watering schedules. Protective sprays of Cleary's 3336 may be applied.
AZALEA Colletotrichum Leaf Spot Roughly circular brown-black leaf spots (about 0.5 cm diam.). Spots often associated with stressed plants. See Cercospora Leaf Spot.
AZALEA Exobasidium Gall Blossoms & leaves develop green-pink-white fleshy galls. Sanitation; See AL Pest Management Handbook.
AZALEA Ovulinia Petal Blight Small white-brown spots enlarge to become large browned areas on the blossoms. See AL Pest Management Handbook.
AZALEA Pestalotia Blight (Secondary) Gray-white dried blotches on foliage, often along leaf edges. Sanitation.
AZALEA Phytophthora Crown & Root Rot Crowns & roots become brown and water-soaked, then dried. Sanitation; See AL Pest Management Handbook.
AZALEA Rhizoctonia Aerial Blight Medium-dark brown spots or blotches on lower leaves may involve 50-100% of leaf area. Dead leaves will fall. See AL Pest Management Handbook.
BENTGRASS Pythium Blight Irregular areas of turf become water-soaked and then pale brown. See ANR-594.
BENTGRASS Ring Nematode Damage
(Criconemoides)
Areas display stunting, yellowing, and dieback. See ANR-523.
BOXWOOD Macrophoma Blight-Stress During the winter, boxwood may change color and take-on a reddish tint. These discolored plants sometimes develop a more serious yellowing and blight with tiny black dots scattered on yellowed leaves; cankers may develop. This is generally a problem of stressed plants. Pruning; proper maintenance.
CAMELLIA Algal Leaf Spot (Cephaleuros) Green or green-red, slightly raised leaf spots with slightly wavy margins. Old spots have white centers. See the AL Pest Management Handbook.
CAMELLIA Colletotrichum Leaf Spot Round, light brown, circular spots which may contain brown-white-orange specks that are the spore bodies. Sanitation. Cleary's 3336 protective sprays.
CAMELLIA Ringspot Virus Yellow or brown rings develop on leaves. Plants may be stunted. Maintain plants with proper fertilization and water schedules.
CEDAR, RED
(JUNIPER)
Cedar Apple Rust (Gymnosporangium) Large (1-3 inch diameter), woody galls on stems develop orange, jelly-like projections (one or more inches long) which protrude from the entire surface of the gall. Remove galls before orange "fingers" develop. Apply protective fungicide sprays to apple and crabapple. See AL Pest Management Handbook.
CEDAR, RED
(JUNIPER)
Pestalotia Tip Blight Tips of twigs dieback. Water & fertilize to promote vigorous plants. Selective pruning.
CHERRY LAUREL Bacterial Leaf Spot (Xanthomonas) Medium to dark-brown circular or slightly irregular spots develop. As spots age, they dry and eventually the whole spot may fall out. Small, faint halos present sometimes. Sanitation; basic copper sulfate may give protective control. See AL Pest Management Handbook.
CHERRY LAUREL Cercospora Leaf Spot Irregular brown spots of variable size. Sanitation of leaves in the fall.
CLEYERA Anthracnose
(Colletotrichum)
Reddish circular-irregularly shaped spots, blotches (about 5 mm diam.) scattered on leaves. Sanitation. Cleary's 3336 or Domain protective sprays.
EUONYMUS Anthracnose (Elsinoe) Brown circular-angular lesions on leaves. Sanitation. See the Alabama Pest Management Handbook.
GERANIUM Bacterial Blight
(Xanthomonas campestris
pv. Pelargonii
)
Black, angular, water-soaked spots on leaves and stems; wilt; dieback. Sanitation; See the AL Pest Management Handbook.
GERANIUM Pythium Stem & Root Rot Lower stems become black and rotted; roots also become brown or black and decayed. See the AL Pest Management Handbook.
GREENHOUSE CROPS Bacterial Leaf Spot Small-large, irregular, dark, wet-looking spots which often become dry in their centers and may have yellow zones or borders at their outer edges. Strict sanitation; eliminate overhead irrigation if possible; copper sprays help some. See AL Pest Management Handbook.
GREENHOUSE CROPS Botrytis Blight See Azalea. See AL Pest Management Handbook. Decrease humidity.
GREENHOUSE CROPS Downy Mildews Diffuse yellow spots on upper leaf surfaces with corresponding areas on lower leaf surfaces showing darker color, often with tan-gray fungal growth See AL Pest Management Handbook for specific controls.
GREENHOUSE CROPS Phytophthora Root Rot Roots become, brown, decayed, water-soaked; the outer cortex easily pulls away from the inner tissues. Sanitation. Check soil water relations and fertilizer levels. Chemical control depends on plant type.
HOSTA Pythium Crown Rot Brown, wet, water-soaked decay at lower stem near the soil line. Sanitation; improve soil drainage; rotate away from Hosta; Subdue 2E after test treatment.
INDIAN HAWTHORNE Entomosporium Leaf Spot Reddish spots with black centers. Sanitation. Protective fungicide sprays.
IRIS, BEARDED Heterosporium Leaf Spot Brown, usually elliptical, sometimes large (1-2 cm) spots. Sanitation. Protective sprays of Cleary's 3336.
JUNIPER Cedar Apple Rust
(Gymnosporangium virginianae,)
Spherical woody galls develop on twigs and branches; with warm wet weather, orange, jelly-like projections or fingers extend from the galls. Remove galls before they develop orange spore projections; See ANR-468.
LEYLAND CYPRESS Phomopsis Twig Canker Sunken circular or elliptical brown lesions on twigs. Sanitation; protective spray of Cleary's 3336.
LEYLAND CYPRESS Cercospora Blight Blight usually starts on lower inner needles. Pruning, sanitation, protective sprays of Cleary's 3336.
LEYLAND CYPRESS Macrophoma, Pestalotia Needle Blight-Secondary Brown needles with tiny black specks that are the spore bodies of these fungi. Usually occurs on stressed or weakened plants. Sanitation.
LEYLAND CYPRESS Macrophoma, Phomopsis Cankers, Maybe Secondary or Weak Pathogens Small, sunken, brown lesions on twigs and small stems; black specks of spore bodies present on lesion surfaces sometimes. Sanitation. Cleary's 3336 protective sprays.
LIGUSTRUM Cercospora Leaf Spot Brown circular or irregularly shaped leaf spots. Sanitation. Improve air circulation. Apply Cleary's 3336 spray. See AL Pest Management Handbook.
LILAC Bacterial Leaf Spot Black, angular, water-soaked spots. Sanitation. See AL Pest Management Handbook.
LILAC Pythium Root Rot Roots are off-color, decayed, water-soaked. Sanitation; Improve soil drainage; crop rotation.
MAGNOLIA Phyllosticta Leaf Spot Small-large (0.5-1 cm) light brown usually circular spots. See the AL Pest Management Handbook under 'Leaf Spot'.
MAPLE, RED Botryosphaeria Canker Dry, cracked, dark brown-black branch lesions. Prune out cankers.
MONDOGRASS Anthracnose
(Colletotrichum)
Brown or reddish-brown blotches on leaf blades. Often blotches are along leaf edges or tips. See the AL Pest Management Handbook.
NANDINA, DWARF Phytophthora Root Rot Roots become water-soaked, brown and eventually dried. Foliage shows, dieback, wilt, poor growth. Sanitation.
OAK Hypoxylon Canker A thick, black, hard fungus layer develops just under bark. Prune out cankers.
PACHYSANDRA Volutella Blight Brown, sunken, shrivelled lesions on stems. Orange dots (fruiting bodies with spores) may be seen on surface of lesions. Prune out damaged areas.
PEAR, BRADFORD Fireblight (Erwinia) Black-colored dieback, blossom blight, twig-tips may have a shepherd's crook. Sanitation; See AL Pest Management Handbook.
PERIWINKLE Pythium Root Rot Roots brown and water-soaked. Sanitation. See AL Pest Management Handbook.
PETUNIA Phytophthora parasitica Crown Rot Cankers and blight areas develop on foliage. Sanitation. Daconil, Echo, Thalonil, and Aliette are labelled.
PETUNIA Pythium Root Rot See Periwinkle. -
PHLOX
(and Other Ornamentals)
Powdery Mildews Buff or white powdery patches on leaves and stems; some distortion of new growth. Sanitation. Cleary's 3336 may be used.
PHLOX
(and Other Ornamentals)
Rhizoctonia Blight Lower leaves become brown blotched with whole leaves and stems sometimes affected. Sanitation. Cleary's 3336 may be used.
PHOTINIA Armillaria Root Rot Decline of plant. Check the lower trunk or roots for a thin, white mycelial layer under the bark. Also look for honey-colored mushrooms. Sanitation of plant and roots. Crop rotation. See ANR-907.
PHOTINIA Entomosporium Leaf Spot Dark red spots (usually 3-4 mm or _ inch diam.) on upper and lower leaf surfaces. Spots often coalesce. Pruning; Fungicide treatment; See Cir. ANR-392 or AL Pest Management Handbook.
PINE, LOBLOLLY Fusiforme Rust
(Cronartium quercuum
f. sp. Fusiforme
)
Rusty, powdery coating appears on the surface of fusiform (elliptical-shaped) swellings on branches and trunks. (Near-by oaks will develop small black leaf spots in late spring). Sanitation in landscape settings; protective fungicide sprays available for nursery situations. See the AL Pest Management Handbook.
PINE, LOBLOLLY Needle Rust
(Coleosporium)
Cream-colored pustules (2-3 mm or _ inch wide and high) develop along the edges of needles. ---
PINE SEEDLINGS,
LONG LEAF
Rhizoctonia Root Rot Brown lesions, often shrivelled, on roots. Sanitation.
PINE, VIRGINIA Fusarium Pitch Canker Sunken, elliptical lesions on branches and trunks covered with pine resin. Sanitation.
PINE, VIRGINIA Needle Rust
(Coleosporium)
Cream-colored pustules (2-3 mm or _ inch wide and high) develop along the edges of needles. --
PRIVET Cercospora Leaf Spot Large (1/4-1/2 inch diam.), medium brown circular or irregular spots. See AL Pest Management Handbook; Sanitation.
QUINCE Fireblight
(Erwinia amylovora)
Blossom blight followed by rapid dieback. Severe pruning.
RED CEDAR Phomopsis Dieback Tips of twigs are brown. The dieback will extend further down the twig as time progresses; canker. Sanitation; See AL Pest Management Handbook.
RHODODENDRON
AZALEA
Botryosphaeria Canker Elongated, elliptical, sunken, brown cankers with margins that are often cracked. Sanitation.
RHODODENDRON Cercospora Leaf Spot Brown spots (5-10 mm or 1/4-1/2 inch diam.) usually circular. Protective sprays of Cleary's 3336 or Domain. Sanitation.
ROSE Black Spot
(Diplocarpon rosa)
Black, circular spots with feathery edges. See ANR-505 & AL Pest Management Handbook.
ROSE Coniothyrium Canker A brown oval or roughly oval sunken lesion on rose canes. Microscopic exam usually required to distinguish this canker from some others. Sanitation. Apply protective fungicides labelled for black spot control.
ROSE Powdery Mildew
(Sphaerotheca spp.)
White powdery coating on leaves/ stems. See ANR-407 & AL Pest Management Handbook.
ROSE, HYBRID TEA Nectria Canker Sunken cane lesions with some callus production around lesion edges. Sanitation. Protective fungicides labelled for black spot.
THRIFT
(Phlox subulatins)
Anthracnose
(Colletotrichum)
Brown or reddish-brown spots, blotches (1-3 mm diam.) develop. Spot coalescence. Sanitation; protective sprays of Cleary's 3336 or Domain may help.
TULIP Fusarium and Penicillium Bulb Rots Bulbs develop sunken brown-gray dried lesions. Penicillium sporulation may occur as a blue-gray mold on the surface of the sunken rotted area. Sanitation. Bulb dips. See the AL Pest Management Handbook.
VINCA, ANNUAL Rhizoctonia Stem Rot Dark brown, dried, sunken lesion(s) on stems. Dieback of affected stems. Sanitation; remove damaged plants; Chipco 26019, Cleary's 3336, or Domain protective sprays; See AL Pest Management Handbook.
WAX MYRTLE Botryosphaeria Canker Dark, cracked, slightly sunken lesions on branches. Often follows cold injury. Pruning.


UPCOMING EVENTS

June 20 - 23, 2001:
2001 Southeast Greenhouse Conference and Trade Show.
Greenville, SC.
For more information call 877-927-2775; www.sgcts.org

July 24 - 28, 2001:
Cullowhee Conference: Native Plants in the Landscape.
Western Carolina University in Cullowhee, North Carolina
For more information call 770-922-7292.

August 2-5, 2001:
SNA 2001 - Southern Nurserymen's Association Researcher's Conference and Trade Show.
Georgia World Congress Center, Atlanta, GA. Contact SNA at 770-973-9026; SNA Infoline at 770-973-4636;
http://www.sna.org

September 30 - October 3, 2001:
Eastern Region International Plant Propagators' Society Annual Meeting.
Lexington, KY. Contact Margot Bridgen, 26 Woodland Road, Storrs, CT 06268; phone 860-429-6818; e-mail mbippser@neca.com

October 11-12, 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.tnnursery.com/mtna

October 18-21, 2001:
Southern Region International Plant Propagators' Society.
Houston, TX. Contact David Morgan at 817-882-4148; fax: 817-882-4121; SR IPPS, P.O. Box 1868, Ft. Worth, TX 76101; e-mail: dmorgan@bsipublishing.com

November 30 - December 1, 2001:
The Great Southern Tree Conference.
Contact Heather Nedley at hnedley@fnga.org; 1-800-375-3642.

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

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.