JUNE 1999

Hello June, Hello Alabama Summers! A few propitious rains and our landscapes and fields can look great. A few weeks of skipped rains and the only thing that seems to flourish are the weeds. We have been fortunate in central Alabama with some well-spaced rains. I saw a goldenraintree in full bloom today, June 1, 1999. It was beautiful.

Our “What’s Blooming Page is always a month behind this year because we have to take the pictures, develop them and then scan and post them to the page. By the time we get through the process, it is next month. I have a digital camera that I use occasionally which shortens the process and a camera that I use occasionally but the quality is still not as good as a 35mm camera (at least in the range I can afford). We are building for the future. We welcome your submissions. I enjoy this part of our web page; it gets me out in the garden to see what is happening and I can call it work.

SCENES FROM THE SPOTLIGHT ON ALABAMA GREEN INDUSTRY BY THE
AGRIBUSINESS COUNCIL (HELD IN MONTGOMERY)

The Spotlight on Alabama Green Industry by the Agribusiness Council was a big success in Montgomery last month. All the legislators left knowing that the Green Industry was an important part of Alabama’s economy and deserving of their attention. We made a video to show the legislators the diversity of our industry. We gave them all we could squeeze into seven minutes. If you would like to use the tape for a school project or other meeting, “The Green Industry” is available through your county Extension office.

We learn from our failures as well as our successes. Chamaecyparis thyoides, white cedar, is gaining popularity as a landscape plant and a potential Christmas tree. It is a native plant found in bogs or on stream banks. Many of our plants that you bring out of situations like this often do well in more upland sites. Bald cypress (Taxodium distichum) and Swamp magnolia (Magnolia virginiana) are good examples of this. In an irrigation research project we have been using this plant as a test species. In two separate projects, we have had an irrigation glich that has left the irrigation off for 3 days. Both Leyland Cypress and Arizona Cypress survived the ordeal with no apparent damage. White Cedar, however, flamed out. Soil scientists often speak of permanent wilting point in plants where water deprivation has been so great that Niagara Falls could not bring them back to life. This is what these plants looked like. Just as Leyland Cypress can not withstand prolonged saturation, white cedar needs to be pampered with water. I hope no one repeats our disaster. Automation does not eliminate the necessity to walk the rows each day scouting for pests and noting irrigation heads and the condition of each plant.

Ken Tilt

Have a great month! The Horticulture Department and Auburn University were created to serve all the people of Alabama and we enjoy helping when we can. Send us your questions, comments, suggestions, and ideas.


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:

1. OAK-LEAF HYDRANGEA WILL SOON BECOME ALABAMA'S OFFICIAL STATE WILDFLOWER
2. COMMON GREEN SPACE ENHANCES QUALITY OF LIFE
3. ROSE SENSITIVITY TO BLACK SPOT AND CERCOSPORA LEAF SPOT
4. MIRACID VS. BLACKSPOT ON ROSES
5. ROSES ON THE INTERNET
6. CHLOROTHALONIL FUNGICIDES PROHIBITED FOR HOME LAWN USES
7. CRAPEMURDER DEMONSTRATION CONTINUES
8. INVASIVE SPECIES EXECUTIVE ORDER
9. OVERVIEW OF ALABAMA PLANT DISEASES ON ORNAMENTALS IN 1998
10. JACKIE MULLEN'S PLANT PATHOLOGY REPORT
11. UPCOMING EVENTS


OAK-LEAF HYDRANGEA WILL SOON BECOME ALABAMA'S OFFICIAL STATE WILDFLOWER


The Alabama Legislature has approved a bill that names the oak-leaf hydrangea Alabama's official state wildflower. It is expected that the governor will sign the bill. From 1927 until 1959 the goldenrod was the official state flower of Alabama. It was then changed to the camellia. This change did not sit well with many opponents who claimed that the camellia wasn't native to the state. Camellia lovers answered that accusation with the fact that camellias don't cause hay fever and that camellia colors matched the colors on the state flag.


The Wildflower Society, on the other hand, wanted the state to also name a native plant to represent the state. The oak-leaf hydrangea (Hydrangea quercifolia Bart) was their very logical choice for a number of reasons. Its existence was documented even before Alabama became a state. William Bartram, a naturalist who traveled in the state in 1775-1776, named the oak-leaf hydrangea in his book "Travels" (published in 1791). Growing in every region and every soil type in Alabama, the six foot high plant produces white flowers from May throughout the summer.

(from Phillip Rawls in The Montgomery Advertiser)

COMMON GREEN SPACE ENHANCES QUALITY OF LIFE

Researchers from the University of Illinois and the University of Chicago have concluded, after studying 145 female heads of households in the Robert Taylor Homes in Chicago, that "individuals living adjacent to greener common spaces had more social activities and more visitors and had stronger feelings of belonging." It may be an important survival strategy for those who live in poverty - a way of sharing common resources and building a social network. They theorize that grass and trees and simple landscaping draw people outside where casual contact with fellow residents can lead to friendships.

(from the Gannett News Service, published in the Montgomery Advertiser)

ROSE SENSITIVITY TO BLACKSPOT AND CERCOSPORA LEAF SPOT

Blackspot is a particularly damaging disease that can compromise the growth and beauty of roses in Alabama, particularly because of the wet and warm climate that characterizes our summers. The negative impact of blackspot and cercospora leaf spot is common knowledge among rose fanciers and growers who must spend a great deal of energy and money on season-long, intensive fungicide spraying programs. What is at yet unknown is how these two diseases will impact the newer varieties of shrub and ground cover roses. A study has been conducted to examine susceptibility of these new cultivars and the results will be of interest to growers. There were a few new cultivars that only suffered light to moderate damage. These plant selections will fit well into a low maintenance landscape.

A VARIETY OF SHRUB ROSES FROM THE AUBURN UNIVERSITY STUDY
The significant susceptibility differences are listed in the table below. The cultivars that performed best relative to heat stress and disease resistance are: 'Ralph's Creeper', 'Happy Trails', Rosa mutabulis and Rosa wichuraina. The remaining roses would have to be treated with an intensive fungicide spray program to take them through the summer.

Reaction of Cultivars of Groundcover and Shrub Roses to Black Spot and Cercospora Leaf Spot, 1998

CultivarBlack Spot
Rating
CultivarBlack spot
Rating
Royal Bonica6.6Livin' Easy5.2
Betty Prior6.6The Fairy---
Sevillana6.4Fushia Meidiland4.8
First Light6.4Nozomi4.4
Carefree Delight6.2White Flower Carpet4.2
Bonica6.1Red Cascade3.8
Cherry Meidiland6.0Rosa mutabulis3.8
Nearly Wild5.8Rosa wichuraina3.6
Jeeper's Creepers5.6Happy Trails3.4
Peach Meidiland5.6Magic Carpet3.0
Sea Foam5.2Ralph's Creeper3.0
Mystic Meidiland5.2Flower Carpet2.6
..Petite Pink Scotch1.0
Black spot and Cercospora leaf spot were rated on a 1 to 10 scale where
1 = no disease
2 = very few spots in lower canopy
3 = a few spots in lower and upper canopy
4 = some spots with light defoliation in lower canopy
5 = spots noticeable with noticeable defoliation
6 = spots numerous with significant (50+%) defoliation
7 = spots numerous with severe defoliation (75+%)
8 = upper canopy badly diseased with high (90%) defoliation
9 = very few remaining leaves covered with spots
10 = plant defoliated.
(from Austin Hagan, J. Randy Akridge, and Ken Tilt, Auburn University)

MIRACID VS. BLACKSPOT ON ROSES

The daunting problem of blackspot on roses may have an effective treatment. A St. Louis rose grower, upon running out of Miracle-Gro borrowed some Miracid fertilizer for acid-loving plants. Application was made by a hose-end sprayer. The next day he was disappointed to see that many leaves fell off the plants. What he subsequently began to notice was that the blackspot lesions on the remaining leaves did not spread and that new ones did not appear. Since he was experiencing a particularly invasive infestation of blackspot on his 500 roses, he continued spraying with Miracid each week. No subsequent blackspot appeared. He communicated his findings to other rose growers, some of whom tried his technique and found similar results.

During the 1999 rose growing season several growers will be testing Miracid for the control of blackspot. Because of these results Miracid will also be tested as a fungicide on other plants. These are not scientific, but rather anecdotal findings, but it is assumed that the science will follow with similar results. People have been transmitting information like this on Internet garden discussion groups. Scientific experimentation should clarify how it works with resulting recommendations for the control of fungi on many different plants. You can find Miracid Plant Food for Acid-Loving Plants (The Scotts Company) in garden centers, hardware, and discount stores.

Because of potential phytotoxicity, it is suggested that you water plant beds prior to foliar spraying. Do not spray roses when the heat index is above 85 degrees. The following cultivars appear to be particularly sensitive to Miracid: 'Hansa', 'Topaz Jewel', 'Sunny June', 'Carefree Bunch', 'Joseph's Coat', 'The Fairy', Eglantyne',and 'Garten Direktor Otto Linne'. Petunias, gladiolas, irises, and many other flowers are not sensitive to this product. It may control mildew on lilacs and rust on hollyhocks. If you apply Miracid with a hose-end sprayer don't tilt the sprayer as it can change the spray concentration. And don't apply a regular soluble fertilizer as a foliar spray while using Miracid as the fungicidal effect will likely be eliminated. Apply the fertilizer at the base of the plant. Some growers have used less expensive products with similar results.

(from HORTIDEAS ONLINE, MAY 1999 16(5), page 13)

ROSES ON THE INTERNET

A first-ever online chat session from All-America Rose Selections will give rose growers the opportunity to talk online with John K. Walden, one of the nation’s leading rose experts. Walden is research manager and plant breeder at Bear Creek Gardens/Jackson & Perkins in Somis, Calif. The chat session will be June 24 from 9-10 p.m. Eastern on http://www.rose.org

(from Weekly NMPRO by David Morgan, 6/1/99)

CHLOROTHALONIL FUNGICIDES PROHIBITED
FOR HOME LAWN USES

by Austin Hagan
Auburn University Exension Plant Pathologist

For the past decade or more, fungicides that contained the active ingredient chlorothalonil, which is sold under the trade names Daconil, liquid Lawn Disease Control, Fungi-Gard, etc. have been widely used by both landscapers and homeowners on Alabama's home lawns. Chlorothalonil not only has good activity against a variety of diseases on warm- and cool-season turfgrasses but also those on many landscape ornamentals. This fungicide is also used for the control of foliar diseases on a number of important vegetable, fruit, and field crops.

For years, chlorothalonil, which is classified by the EPA as a B2 carcinogen, has been under a regulatory cloud. The problem is that this fungicide is the best broad-spectrum, contact fungicide on the market. The EPA has been aware of that fact and, until the 1996 Food Quality Protection Act was passed, had not acted. Well, now it has.

Under FQPA, all pesticide exposures from food, drinking water, the landscape, and other uses (total exposure) must be considered when determining allowable pesticide levels in food. Under the old FIFRA guidelines, non-food uses of a given pesticide had little or no bearing on setting pesticide tolerances in food crops. Now, fungicide uses on home lawns, golf courses, and sod farms are given the same weight by the EPA when filling the "risk cup" as those used on vegetables or any other food crop.

Due to the high use rates and frequent application intervals found on its label chlorothalonil was especially vulnerable to such regulatory action. Also, the EPA's misconceptions concerning the use of fungicides on golf courses added to the confusion concerning exposure to chlorothalonil residues. The EPA initially assumed that every acre of every golf course in the United States is treated year-round with the full rate of chlorothalonil: greens, tees, fairways, bunkers, everything. Anyone who has worked with the golf course industry knows that fungicide applications are largely restricted (at best) to the intensively managed greens and tees. On all but the most exclusive coures, the fairways and roughs are left to fend for themselves. On many low-budget courses, use of any fungicide anywhere, including chlorothalonil, is minimal. The mid-South, with its modest number of bentgrass courses, is really the only region where year-round fungicide applications are made to greens and tees and chlorothalonil is not the fungicide of choice for Pythium and brown patch control.

Chlorothalonil's "risk cup" was overflowing and something had to go. That something turned out to be the residential lawn uses of Daconil 2787, Fungi-Gard, Liquid Lawn Disease Control, and any other generic chlorothalonil products on the retail market. That prohibition on residential lawns goes for the lawn care industry, not just the homeowner. All other uses, including ornamentals in residential landscapes, have been retained so far, as have those for golf courses, sod farms, nurseries, and greenhouses. The re-entry interval (REI) for Daconil on nursery and greenhouse crops was cut from 48 hours to 12 hours. As with any discontinued use, existing stocks will be sold under the old labels. Residential turf uses will be deleted from the label of any new product manufactured. All chlorothalonil fungicides will soon be deleted from our (ANR) residential turf disease publications and the Alabama Pest Management Handbook (ANR-500, Vol. 2).

There are no quick replacements for Daconil 2787 and the other chlorothalonil fungicides on shelves at local stores or garden centers. At some retail outlets, it's the only fungicide AI on the shelf! Chlorothalonil was my top choice for Helminthosporium leaf spot, Gray leaf spot, and brown patch control on residential lawns. Its replacements are generally less effective, hard to find, more expensive, or a combination of all three. Some formulation of mancozeb (i.e., Fore or Dithane T/O) or Immunex (Banner Maxx) will be the most readily available products. At some point, other triazole fungicides such as Eagle and Bayleton may be sold for residential turf use through retail outlets: they will be expensive.

Zeneca Corporation, the manufacturer of Daconil 2787, did not come away from the EPA empty handed. Heritage 50W, a broad-spectrum systemic turf fungicide, was cleared for use on residential lawns. The question is whether or not this fungicide will be available only to the lawn care industry. Will the general public have access to it? Heritage 50W has been quickly adopted by the golf course industry, particularly in this area, for the control of Pythium blight, anthracnose, and several other damaging diseases on bentgrass greens and tees. It is quite expensive at $300-plus per pound of product. Can't wait to see the looks on peoples' faces when they see the price of this stuff at the local Wal-Mart.

(Published in The Alabama Master Gardener Newsletter, May 1999).

CRAPEMURDER DEMONSTRATION CONTINUES

We began a crapemyrtle recovery pruning demonstration in February in Decatur, Alabama. Decatur is the self-proclaimed Crapemyrtle City. One of the main streets going into town had crapemyrtles that had been pruned in what has become the accepted high maintenance method for pruning crapemyrtles. Maintenance personnel and home gardeners cut their trees about chest high each year leaving ugly stubs followed by a witches broom of growth arising below the cuts. This process, referred to as crapemurder by Southern Living Magazine, ruins the structure and some of the ornamental appeal of these trees.


The purpose of the demonstration we began in February was to cut the trees to the ground, allow the suckers to emerge, select 3, 5 or 7 canes evenly distributed around the stump and remove all of the other suckers. Tre-Hold is applied to the pruning cuts to inhibit future suckering. We also selected 2 or 3 crapemurdered trees and tried to artistically prune them to try to restore them to their natural form. (See pictures below) This is a time consuming process and probably not practical for a maintenance crew. We also found a few trees that had been cut to the ground in previous years and all the suckers were allowed to grow creating a dense shrub.




We pruned the excess canes from these trees and applied Tre-Hold to the cuts to allow these trees to return to their natural habit. The natural habit is not only the most aesthetically appealing form but also requires the least maintenance. We will keep you posted on the progress of the project and continue to post pictures showing the recovery.


(Ken Tilt)


INVASIVE SPECIES EXECUTIVE ORDER

Below is a copy of the executive order released by the Office of the Press Secretary, The White House, on Invasive Species. It will start a program to deal with the threat of invasive species. All items will be put on a "green list", meaning that they will be considered guilty until proven innocent.

STATEMENT BY THE PRESIDENT

Today, I am signing an Executive Order directing federal agencies to expand and coordinate their efforts to combat a serious environmental threat: the introduction and spread of plants and animals not native to the United States.

Many Americans are all too familiar with gypsy moths and other non-native insects that devour our gardens and trees. Few realize, however, that countless other non-native plants and animals are upsetting nature's balance, squeezing out native species, causing severe economic damage, and transforming our landscape.

Those affected range from Western ranchers plagued by a weed called leafy spurge to Chicago homeowners whose stately maple trees have fallen prey to the Asian long-horned beetle. Some experts estimate the cost to the American economy to be as high as $123 billion a year.

The Executive Order mobilizes the federal government to defend against these aggressive predators and pests.

Led by the Departments of the Interior, Agriculture, and Commerce, federal agencies will work together to prevent the introduction of non-native species and control those already here. My fiscal year 2000 budget proposes an additional $29 million to support these efforts, and I urge Congress to join us in protecting our economy and our natural heritage against the threat of non-native species.

--- The following is the EXECUTIVE ORDER from THE WHITE HOUSE, Office of the Press Secretary, released on February 3, 1999:

By the authority vested in me as President by the Constitution and the laws of the United States of America, including the National Environmental Policy Act of 1969, as amended (42 U.S.C. 4321 et seq.), Nonindigenous Aquatic Nuisance Prevention and Control Act of 1990, asamended (16 U.S.C. 4701 et seq.), Lacey Act, as amended (18 U.S.C. 42), Federal Plant Pest Act (7 U.S.C. 150aa et seq.), Federal Noxious Weed Act of 1974, as amended (7 U.S.C. 2801 et seq.), Endangered Species Act of 973, as amended (16 U.S.C. 1531 et seq.), and other pertinent statutes, to prevent the introduction of invasive species and provide for their control and to minimize the economic, ecological, and human health impacts that invasive species cause, it is ordered as follows:

Section 1. Definitions.
(a) "Alien species" means, with respect to a particular ecosystem, any species, including its seeds, eggs, spores, or other biological material capable of propagating that species, that is not native to that ecosystem.

(b) "Control" means, as appropriate, eradicating, suppressing, reducing, or managing invasive species populations, preventing spread of invasive species from areas where they are present, and taking steps such as restoration of native species and habitats to reduce the effects of invasive species and to prevent further invasions.

(c) "Ecosystem" means the complex of a community of organisms and its environment.

(d) "Federal agency" means an executive department or agency, but does not include independent establishments as defined by 5 U.S.C. 104.

(e) "Introduction" means the intentional or unintentional escape, release, dissemination, or placement of a species into an ecosystem as a result of human activity.

(f) "Invasive species" means an alien species whose introduction does or is likely to cause economic or environmental harm or harm to human health.

(g) "Native species" means, with respect to a particular ecosystem, a species that, other than as a result of an introduction, historically occurred or currently occurs in that ecosystem.

(h) "Species" means a group of organisms all of which have a high degree of physical and genetic similarity, generally interbreed only among themselves, and show persistent differences from members of allied groups of organisms.

(i) "Stakeholders" means, but is not limited to, State, tribal, and local government agencies, academic institutions, the scientific community, nongovernmental entities including environmental, agricultural, and conservation organizations, trade groups, commercial interests, and private landowners.

(j) "United States" means the 50 States, the District of Columbia, Puerto Rico, Guam, and all possessions, territories, and the territorial sea of the United States.

Sec. 2. Federal Agency Duties. (a) Each Federal agency whose actions may affect the status of invasive species shall, to the extent practicable and permitted by law,

(1) identify such actions;

(2) subject to the availability of appropriations, and within Administration budgetary limits, use relevant programs and authorities to: (i) prevent the introduction of invasive species; (ii) detect and respond rapidly to and control populations of such species in a cost-effective and environmentally sound manner; (iii) monitor invasive species populations accurately and reliably; (iv) provide for restoration of native species and habitat conditions in ecosystems that have been invaded; (v) conduct research on invasive species and develop technologies to prevent introduction and provide for environ-mentally sound control of invasive species; and (vi) promote public education on invasive species and the means to address them; and

(3) not authorize, fund, or carry out actions that it believes are likely to cause or promote the introduction or spread of invasive species in the United States or elsewhere unless, pursuant to guidelines that it has prescribed, the agency has determined and made public its determination that the benefits of such actions clearly outweigh the potential harm caused by invasive species; and that all feasible and prudent measures to minimize risk of harm will be taken in conjunction with the actions.

(b) Federal agencies shall pursue the duties set forth in this section in consultation with the Invasive Species Council, consistent with the Invasive Species Management Plan and in cooperation with stakeholders, as appropriate, and, as approved by the Department of State, when Federal agencies are working with international organizations and foreign nations.

Sec. 3. Invasive Species Council. (a) An Invasive Species Council (Council) is hereby established whose members shall include the Secretary of State, the Secretary of the Treasury, the Secretary of Defense, the Secretary of the Interior, the Secretary of Agriculture, the Secretary of Commerce, the Secretary of Transportation, and the Administrator of the Environmental Protection Agency. The Council shall be Co-Chaired by the Secretary of the Interior, the Secretary of Agriculture, and the Secretary of Commerce. The Council may invite additional Federal agency representatives to be members, including representatives from subcabinet bureaus or offices with significant responsibilities concerning invasive species, and may prescribe special procedures for their participation. The Secretary of the Interior shall, with concurrence of the Co- Chairs, appoint an Executive Director of the Council and shall provide the staff and administrative support for the Council.

(b) The Secretary of the Interior shall establish an advisory committee under the Federal Advisory Committee Act, 5 U.S.C. App., to provide information and advice for consideration by the Council, and shall, after consultation with other members of the Council, appoint members of the advisory committee representing stakeholders. Among other things, the advisory committee shall recommend plans and actions at local, tribal, State, regional, and ecosystem- based levels to achieve the goals and objectives of the Management Plan in section 5 of this order. The advisory committee shall act in cooperation with stakeholders and existing organizations addressing invasive species. The Department of the Interior shall provide the administrative and financial support for the advisory committee.

Sec. 4. Duties of the Invasive Species Council. The Invasive Species Council shall provide national leadership regarding invasive species, and shall:

(a) oversee the implementation of this order and see that the Federal agency activities concerning invasive species are coordinated, complementary, cost-efficient, and effective, relying to the extent feasible and appropriate on existing organizations addressing invasive species, such as the Aquatic Nuisance Species Task Force, the Federal Interagency Committee for the Management of Noxious and Exotic Weeds, and the Committee on Environment and Natural Resources;

(b) encourage planning and action at local, tribal, State, regional, and ecosystem-based levels to achieve the goals and objectives of the Management Plan in section 5 of this order, in cooperation with stakeholders and existing organizations addressing invasive species; (c) develop recommendations for international cooperation in addressing invasive species;

(d) develop, in consultation with the Council on Environmental Quality, guidance to Federal agencies pursuant to the National Environmental Policy Act on prevention and control of invasive species, including the procurement, use, and maintenance of native species as they affect invasive species;

(e) facilitate development of a coordinated network among Federal agencies to document, evaluate, and monitor impacts from invasive species on the economy, the environment, and human health;

(f) facilitate establishment of a coordinated, up-to- date information-sharing system that utilizes, to the greatest extent practicable, the Internet; this system shall facilitate access to and exchange of information concerning invasive species, including, but not limited to, information on distribution and abundance of invasive species; life histories of such species and invasive characteristics; economic, environmental, and human health impacts; management techniques, and laws and programs for management, research, and public education; and

(g) prepare and issue a national Invasive Species Management Plan as set forth in section 5 of this order.

Sec. 5. Invasive Species Management Plan. (a) Within 18 months after issuance of this order, the Council shall prepare and issue the first edition of a National Invasive Species Management Plan (Management Plan), which shall detail and recommend performance-oriented goals and objectives and specific measures of success for Federal agency


OVERVIEW OF ALABAMA PLANT DISEASES ON ORNAMENTALS IN 1998

Ornamental samples were abundant with 103 different plant type submissions and 281 different biotic diseases diagnosed. The following are some of the diseases identified: Phytophthora or Pythium root rot diseases on numerous plant samples; Exobasidium gall on azalea and camellia; Volutella blight on boxwood; Nectria canker on boxwood; crown gall on ornamental cherry, euonymus, Bradford pear, rose; Phytophthora aerial blight on periwinkle; anthracnose diseases on cleyeara, Leyland cypress, dogwood, euonymus, holly, ligustrum, maple, mondograss, pansy, shasta daisy; Botryosphaeria canker and Seiridium canker on Leyland cypress; Phytophthora blight on dogwood; Thielaviopsis black root rot of holly; Entomosporium leaf spot of Indian hawthorn and Photinia; Seiridium canker of juniper; Myrothecium petiole rot of pansy; powdery mildew of hydrangea, crape myrtle, dogwood; Sclerotium rolfsii southern blight on lily.


JACKIE MULLEN'S PLANT PATHOLOGY REPORT

MONTHLY PLANT PROBLEM REPORT

Azalea gall, caused by the fungus Exobasidium vaccinii, is commonly seen at this time of year. Flowers, leaves and young shoots may become swollen, fleshy galls. As the galls mature, the fungus will produce a white coating of spores on the gall surface. If galls are detected and removed before they become white, disease spread is greatly reduced. New infections this spring will develop into new galls next spring. Usually disease control can be achieved by sanitation. Where sanitation is not possible, protective sprays of Bayleton T/O or Strike 25W may be applied. This fungus will cause gall development on azaleas and camellias.

Algal leaf spot was noted on camellia, but it often occurs on magnolia. Wet conditions are required for the development of this disease. The alga develops on the leaf surface as greenish or red greenish spots which are slightly raised with wavy margins. In many cases this algal spot is parasitized by the lichen Strigulla. The presence of the lichen causes the leaf spots to appear grayish white color. Disease control usually requires a decrease in humidity and moisture. For some plants, a copper protective spray is labelled for control of this disease.

Fireblight on ornamental pear was submitted to the lab in April. Usually, blossoms become infected and become black. The blackened condition typically spreads from the blossoms down into the petioles and from there into the small twigs. Eventually water soaked cankers form on the tree trunk. Disease control requires strict sanitation. Blighted and cankered limbs should be pruned, making cuts 10-16 inches beyond the edge of the lesion. Streptomycin 17.1W, Kocide 101 77W; or Phyton 27 protective sprays are effective when applied to the blossoms.

Anthracnose was noted on liriope, English ivy, camellia, and pansy. Leaf spot symptoms vary, depending upon the plant involved. Usually the spots are circular or oval. On camellia and English ivy, spots are usually brown and circular, oval, or slightly irregular in shape. Tiny black dots (reproductive bodies) may be present in the spots; sometimes these bodies are arranged in a circular or target pattern. In liriope, spots are usually white or cream colored or light brown. Sometimes the tip of the leaf is affected and black bodies are scattered over the spot or blotch area. Pansy anthracnose spots tend to be circular and white, containing tiny black bodies in a ring pattern.

John Olive at the Mobile (Springhill) substation noted bacterial leaf spot on Dieffenbachia and Syngonium. Virus symptoms (suspect impatiens necrotic spot virus, INSV) were noted on some impatiens at the substation. John commented that the INSV vector, thrips, is sometimes difficult to detect, and the use of sticky cards is helpful.

1999 April Plant Diseases Seen In The Plant Diagnostic Lab

(Listed by plant, diagnosis and county. Asterisks indicates a nursery/greenhouse and those counties are not reported)

  • AZALEA - Azalea Gall (Exobasidium) Marion
  • AGLAONEMA - Bacterial Leaf Spot - *
  • BOXWOOD - Fusarium Twig Canker - Lauderdale
  • CAMELLIA - Algal Leaf Spot (Cephaleuros) - Choctaw
  • CAMELLIA - Anthracnose (Colletotrichum) - Lee
  • CHRYSANTHEMUM - Rhizoctonia Root Rot - *
  • ELEAGNUS - Sooty Mold - Tuscaloosa
  • IVY, ENGLISH - Anthracnose (Colletotrichum)- Jefferson
  • IVY, ENGLISH - Botryosphaeria Canker - Lee
  • IVY, ENGLISH - Edema - *
  • IVY, ENGLISH - Fusarium/Pythium Root Decay - Jefferson, Lee
  • LIRIOPE - Anthracnose (Colletotrichum)- Lee
  • PINE - Pine Needle Rust (Coleosporium) - Hale
  • ROSE - Pythium Associated Root Decay - *
Disease Possibilities For May

We are aware of impatiens necrotic spot virus on greenhouse impatiens. (ELISA confirmed.)

The list below includes some common disease problems received in the lab during May of the past few years. Comments on control practices are brief. Refer to the Ala. Pest Management Handbook or appropriate fact sheet or disease notes publications for details on disease control.

Brief Disease Descriptions and Control Recommendations for Diseases Often Seen in May. The following entries are in this order: Plant/Disease/Description/Control